Astronomy Picture of the Day |
APOD: 2024 April 15 – The Cigar Galaxy from Hubble and Webb
Explanation:
Something strange happened to this galaxy, but what?
Known as the
Cigar Galaxy and cataloged as
M82,
red glowing gas and dust are being cast out from the center.
Although this
starburst galaxy was surely stirred up by a recent pass near its
neighbor,
large spiral galaxy M81,
this doesn't fully explain the source of the
red-glowing outwardly expanding gas and
dust.
Evidence indicates that this material is being driven out by the combined emerging
particle winds
of many stars, together creating a
galactic superwind.
In the featured images, a
Hubble Space Telescope image in
visible light
is shown on the left, while a
James Webb Space Telescope image of the central region in
infrared light
is shown on the right.
Detailed inspection of the
new Webb image shows, unexpectedly,
that this red-glowing dust is associated with
hot plasma.
Research into the nature of
this strange nearby galaxy will surely continue.
APOD: 2023 August 2 – M82: Galaxy with a Supergalactic Wind
Explanation:
Why is the Cigar Galaxy billowing red smoke?
M82, as this
starburst galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the red-glowing outwardly
expanding gas and dust, however.
Evidence indicates that this gas and dust is being
driven out by the combined emerging
particle winds of many stars, together creating a galactic
superwind.
The dust particles are
thought to originate
in M82's interstellar medium and are actually
similar in size to particles in cigar smoke.
The featured photographic mosaic highlights a
specific color of
red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas and dust.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light and can be seen in visible light with a small
telescope
towards the constellation of the Great Bear
(Ursa Major).
APOD: 2023 May 4 - The Galaxy, the Jet, and a Famous Black Hole
Explanation:
Bright elliptical galaxy Messier 87 (M87)
is home to the
supermassive black hole captured in 2017 by planet Earth's
Event Horizon Telescope
in the first ever image of a black hole.
Giant of the Virgo galaxy cluster about 55 million light-years away,
M87 is the large galaxy rendered in blue hues in this infrared
image
from the Spitzer Space telescope.
Though M87 appears mostly featureless and cloud-like,
the Spitzer image does record details of relativistic
jets blasting from the galaxy's central region.
Shown in the inset at top right, the jets themselves
span thousands of light-years.
The brighter jet seen on the
right is approaching and close to our line of sight.
Opposite, the shock created by the otherwise unseen receding jet
lights up a fainter arc of material.
Inset at bottom right, the
historic black hole image is shown
in context, at the center of giant galaxy and relativistic jets.
Completely unresolved in the Spitzer image, the
supermassive
black hole surrounded by infalling material is the source of enormous energy driving
the
relativistic jets from the center of active galaxy M87.
The Event Horizon Telescope image of M87
has now been enhanced to reveal a
sharper view of the famous supermassive black hole.
APOD: 2023 January 20 - Galaxy Wars: M81 and M82
Explanation:
The two dominant galaxies near center
are far far away, 12 million light-years distant
toward the northern constellation of the Great Bear.
On the right, with grand spiral arms and bright yellow core is
spiral galaxy M81.
Also known as Bode's galaxy, M81 spans some 100,000
light-years.
On the left is cigar-shaped
irregular galaxy M82.
The pair have been locked in gravitational combat for a billion years.
Gravity
from each galaxy has profoundly affected the other during
a series of cosmic close encounters.
Their last go-round lasted about 100 million years and
likely raised density waves rippling around
M81, resulting in the richness of
M81's
spiral arms.
M82
was left with violent star forming regions and
colliding gas clouds so energetic that the galaxy
glows in X-rays.
In the next few billion years, their
continuing gravitational encounters will result in a merger, and a
single galaxy will remain.
This extragalactic scenario also includes other members of the interacting
M81 galaxy group
with NGC 3077 below and right of the large spiral, and
NGC 2976 at upper right in the frame.
Captured under dark night skies
in the Austrian Alps, the foreground of
the wide-field image is filled with integrated flux nebulae.
Those faint, dusty interstellar clouds
reflect starlight above the plane of our own Milky Way galaxy.
APOD: 2021 July 9 - M82: Starburst Galaxy with a Superwind
Explanation:
M82 is a starburst galaxy
with a superwind.
In fact,
through ensuing supernova explosions and
powerful winds from massive stars,
the burst of star formation in M82
is driving a prodigious outflow.
Evidence for the superwind
from the galaxy's central regions
is clear in sharp telescopic snapshot.
The composite image highlights emission from
long outflow filaments of atomic hydrogen gas in reddish hues.
Some of the gas in the superwind,
enriched in heavy elements
forged in the massive stars,
will eventually escape into
intergalactic space.
Triggered by a
close encounter with
nearby large galaxy M81,
the furious burst of star formation in M82 should last about
100 million years or so.
Also known as the Cigar Galaxy for its elongated visual appearance,
M82 is about 30,000 light-years across.
It lies 12 million light-years away near the northern boundary of
Ursa Major.
APOD: 2021 April 15 - The Galaxy, the Jet, and a Famous Black Hole
Explanation:
Bright elliptical galaxy Messier 87 (M87)
is home to the
supermassive black hole captured by planet Earth's
Event Horizon Telescope
in the first ever image of a black hole.
Giant of the Virgo galaxy cluster about 55 million light-years away,
M87 is the large galaxy rendered in blue hues in this infrared
image from the Spitzer Space telescope.
Though M87 appears mostly featureless and cloud-like,
the Spitzer image does record details of relativistic
jets blasting from the galaxy's central region.
Shown in the inset at top right, the jets themselves
span thousands of light-years.
The brighter jet seen on the
right is approaching and close to our line of sight.
Opposite, the shock created by the otherwise unseen receding jet
lights up a fainter arc of material.
Inset at bottom right, the
historic black hole image is shown
in context, at the center of giant galaxy and relativistic jets.
Completely unresolved in the Spitzer image, the supermassive
black hole surrounded by infalling material is the source of
enormous energy driving
the relativistic jets from the center of active galaxy M87.
APOD: 2021 March 12 - Messier 81
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky Way Galaxy: big,
beautiful
Messier 81.
Also known as NGC 3031 or Bode's galaxy for its 18th century discoverer,
this grand spiral
can be found toward the northern constellation of Ursa Major, the Great Bear.
The sharp,
detailed telescopic view reveals M81's bright yellow nucleus, blue
spiral arms, pinkish starforming regions, and sweeping
cosmic dust lanes.
Some dust lanes actually run through the galactic disk (left of center),
contrary to other prominent
spiral features though.
The errant dust lanes may be the lingering
result of a close encounter between
M81 and the nearby galaxy M82 lurking outside of this frame.
M81's faint, dwarf irregular satellite galaxy, Holmberg IX,
can be seen just below the large spiral.
Scrutiny of variable stars in M81 has yielded a
well-determined distance
for an external galaxy -- 11.8 million light-years.
APOD: 2020 June 6 - Comet PanSTARRs and the Galaxies
Explanation:
Comet PanSTARRs, C/2017 T2,
shared this stunning telescopic field of
view with galaxies
M81 and M82 on May 22/23.
Of course, the galaxies were some 12 million light-years distant and
the comet about 14 light-minutes away, seen in
planet Earth's sky toward the Big Dipper.
A new visitor
from the Oort Cloud, this
Comet PanSTARRs
was discovered in 2017 by the PanSTARRs survey telescope when
the comet was over 1 light-hour from the Sun, almost as distant
as the orbit of Saturn.
With a beautiful
coma and dust tail,
this comet has been a
solid northern hemisphere performer for telescope wielding
comet watchers this May, following its closest approach to the Sun
on May 4.
In this deep image
from dark California skies the outbound comet even seems to
develop a short anti-tail as it leaves
the inner Solar System.
APOD: 2020 May 15 - Galaxy Wars: M81 and M82
Explanation:
These two galaxies are far far away, 12 million light-years distant
toward the northern constellation of the Great Bear.
On the left, with grand spiral arms and bright yellow core
is spiral galaxy M81, some 100,000
light-years across.
On the right marked by red gas and dust clouds, is irregular galaxy
M82.
The pair have been locked in gravitational combat for a billion years.
Gravity
from each galaxy has profoundly affected the other during
a series of cosmic close encounters.
Their last go-round lasted about 100 million years and
likely raised density waves rippling around
M81, resulting in the richness of
M81's
spiral arms.
M82
was left with violent star forming regions and
colliding gas clouds so energetic the galaxy glows in X-rays.
In the next few billion years, their
continuing gravitational encounters will result in a merger, and a
single galaxy will remain.
APOD: 2020 March 21 - Comet ATLAS and the Mighty Galaxies
Explanation:
Comet ATLAS C/2019 Y4
was discovered by the NASA funded
Asteroid Terrestrial-impact Last Alert System,
the last comet discovery reported in 2019.
Now growing brighter in northern night skies, the comet's pretty
greenish coma is at the upper left of
this telescopic skyview
captured from a remotely operated observatory
in New Mexico on March 18.
At lower right are M81 and M82, well-known as
large, gravitationally interacting galaxies.
Seen through faint dust clouds above the Milky Way,
the galaxy pair lies about 12 million light-years distant, toward
the constellation Ursa Major.
In bound Comet ATLAS is about 9 light-minutes from Earth, still beyond the
orbit of Mars.
The comet's elongated orbit is similar to
orbit of the
Great
Comet of 1844
though, a trajectory that will return
this comet to the inner Solar System in about 6,000 years.
Comet ATLAS
will reach a perihelion
or closest approach to the Sun on May 31 inside the orbit of Mercury and
may become a naked-eye comet
in
the coming days.
APOD: 2019 July 23 - M82: Galaxy with a Supergalactic Wind
Explanation:
Why is the Cigar Galaxy billowing red smoke?
M82, as this
starburst galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the red-glowing outwardly
expanding gas and dust, however.
Evidence indicates that this gas and dust is being
driven out by the combined emerging
particle winds of many stars, together creating a galactic
superwind.
The dust particles are
thought to originate
in M82's interstellar medium and are actually
similar in size to particles in cigar smoke.
The featured photographic mosaic highlights a specific color of
red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas and dust.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope
towards the constellation of the Great Bear
(Ursa Major).
APOD: 2019 April 27 - The Galaxy, the Jet and the Black Hole
Explanation:
Bright elliptical galaxy
Messier 87 (M87) is home to the
supermassive black hole captured by planet Earth's
Event Horizon Telescope
in the first ever image of a black hole.
Giant of the Virgo galaxy cluster about 55 million light-years away,
M87 is the large galaxy rendered in blue hues in this infrared
image
from the Spitzer Space telescope.
Though M87 appears mostly featureless and cloud-like,
the Spitzer image does record details of relativistic
jets blasting from the galaxy's central region.
Shown in the inset at top right, the jets themselves
span thousands of light-years.
The brighter jet seen on the
right is approaching and close to our line of sight.
Opposite, the shock created by the otherwise unseen receding jet
lights up a fainter arc of material.
Inset at bottom right, the
historic black hole image is shown
in context, at the center of giant galaxy and relativistic jets.
Completely unresolved in the Spitzer image, the supermassive
black hole surrounded by infalling material is the source of the
enormous energy driving the relativistic jets from the
center
of active galaxy M87.
APOD: 2019 April 17 - Messier 81
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky Way Galaxy: big,
beautiful
Messier 81.
Also known as NGC 3031 or Bode's galaxy for its 18th century discoverer,
this
grand spiral can be found toward
the northern constellation of Ursa Major, the Great Bear.
The
detailed telescopic view reveals M81's bright yellow nucleus, blue
spiral arms, pink starforming regions, and sweeping
cosmic dust lanes.
Some dust lanes actually run through the galactic disk (left of center),
contrary to other prominent
spiral features though.
The errant dust lanes may be the lingering result
of a close encounter between M81
and its smaller companion galaxy, M82.
Scrutiny of variable stars in M81 has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
APOD: 2017 September 17 - Bright Spiral Galaxy M81
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky
Way Galaxy: big, beautiful M81.
This grand
spiral galaxy can be found toward the northern constellation of the Great
Bear
(Ursa Major).
This superbly
detailed view reveals M81's bright yellow nucleus, blue
spiral arms, and sweeping cosmic dust lanes with a scale comparable to
the
Milky Way.
Hinting at a
disorderly past,
a remarkable dust lane actually runs straight through the
disk, to the left of the galactic center,
contrary to M81's
other prominent
spiral features.
The errant
dust lane may be the lingering result of
a close encounter between
M81
and its smaller companion galaxy, M82.
Scrutiny of variable stars in
M81 has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
APOD: 2017 June 27 - The M81 Galaxy Group through the Integrated Flux Nebula
Explanation:
Distant galaxies and nearby nebulas highlight this deep image of the
M81
Group of galaxies.
First and foremost in this 80-exposure mosaic is the
grand design spiral galaxy
M81, the largest galaxy in the image,
visible on the lower right.
M81 is
gravitationally interacting with
M82 just above it,
a large galaxy with an unusual halo of filamentary red-glowing gas.
Around the image many other galaxies from the
M81 Group of galaxies can be seen, as well as
many foreground Milky Way stars.
This whole
galaxy menagerie
is seen through the glow of an
Integrated
Flux Nebula (IFN), a vast and complex screen of diffuse gas and dust also in our
Milky Way Galaxy.
Details of the red and yellow
IFN, digitally enhanced, were imaged by a
new wide-field camera recently installed at the
Teide
Observatory in the
Canary Islands of
Spain.
APOD: 2016 February 21 - M82: Galaxy with a Supergalactic Wind
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the red-glowing outwardly
expanding gas, however.
Evidence indicates that this gas is being
driven out by the combined emerging
particle winds of many stars, together creating a galactic
superwind.
The featured photographic mosaic highlights a specific color of
red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope
towards the constellation of the Great Bear
(Ursa Major).
APOD: 2016 February 19 - NGC 2403 in Camelopardalis
Explanation:
Magnificent island universe
NGC 2403
stands within the boundaries of the long-necked constellation
Camelopardalis.
Some 10 million light-years distant and about 50,000 light-years
across, the spiral galaxy also seems to have more
than its fair share of giant star forming
HII regions,
marked by the telltale reddish glow of atomic hydrogen gas.
The giant HII regions are energized by clusters of hot, massive stars
that explode as
bright supernovae
at the end of their short and furious lives.
A member of the M81 group of galaxies,
NGC 2403 closely resembles another galaxy with an
abundance of star forming regions that lies
within our own local galaxy group,
M33 the Triangulum Galaxy.
Spiky in appearance,
bright stars in this colorful galaxy
portrait of NGC 2403
are in the foreground, within our own Milky Way.
APOD: 2016 February 3 - Galaxy Wars: M81 versus M82
Explanation:
In the lower left corner, surrounded by blue spiral arms, is spiral galaxy
M81.
In the upper right corner, marked by red gas and dust clouds, is irregular galaxy
M82.
This stunning vista shows these two mammoth galaxies locked in
gravitational combat, as they have been for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around
M81,
resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and colliding gas clouds so energetic the galaxy
glows
in X-rays.
This big battle is
seen from Earth through the faint glow of an
Integrated Flux Nebula,
a little studied complex of diffuse gas and dust clouds in our
Milky Way Galaxy.
In a few billion years only one galaxy
will remain.
APOD: 2015 October 17 - Bright Spiral Galaxy M81
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky Way Galaxy:
big, beautiful M81.
The grand spiral galaxy can be found toward the northern constellation
of the Great Bear
(Ursa Major).
This superbly
detailed image reveals M81's bright yellow nucleus, blue
spiral arms, tell tale pinkish star forming regions, and sweeping
cosmic dust lanes with a scale comparable to
the Milky Way.
Hinting at a disorderly past,
a remarkable dust lane actually runs straight through the
disk, to the left of the galactic center,
contrary to M81's other prominent
spiral features.
The errant dust lane may be the lingering result of a
close encounter between between
M81 and its smaller companion galaxy,
M82.
Scrutiny of variable stars
in M81
has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
M81's dwarf companion galaxy
Holmberg IX
can be seen just above the
large spiral.
APOD: 2015 March 27 - NGC 2403 in Camelopardalis
Explanation:
Magnificent island universe
NGC 2403
stands within the boundaries
of the long-necked constellation
Camelopardalis.
Some 10 million light-years distant and about 50,000 light-years
across, the spiral galaxy also seems to have more
than its fair share of giant star forming
HII regions,
marked by the telltale reddish glow of atomic hydrogen gas.
The giant HII regions are energized by clusters of hot, massive stars
that explode as
bright supernovae
at the end of their short and furious lives.
A member of the M81 group of galaxies,
NGC 2403 closely resembles another galaxy with an
abundance of star forming regions that lies
within our own local galaxy group,
M33 the Triangulum Galaxy.
Spiky in appearance,
bright stars in this colorful galaxy portrait of NGC 2403
lie in the foreground, within our own Milky Way.
APOD: 2014 November 19 - Bright Spiral Galaxy M81
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky
Way Galaxy: big, beautiful M81.
This grand spiral galaxy can be found toward the northern constellation of the Great
Bear
(Ursa Major).
This superbly
detailed view reveals M81's bright yellow nucleus, blue
spiral arms, and sweeping cosmic dust lanes with a scale comparable to
the
Milky Way.
Hinting at a disorderly past,
a remarkable dust lane actually runs straight through the
disk, to the left of the galactic center,
contrary to M81's
other prominent
spiral features.
The errant
dust lane may be the lingering result of
a close encounter between
M81 and its smaller companion galaxy, M82.
Scrutiny of variable stars in
M81 has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
APOD: 2013 September 25 - M81 versus M82
Explanation:
Here in the Milky Way galaxy we have astronomical front row seats
as M81 and M82 face-off, a mere 12 million light-years away.
Locked in a gravitational struggle for the
past billion years or so, the two bright galaxies are captured in
this deep
telescopic snapshot, constructed from 25 hours of image data.
Their most recent close encounter likely resulted in
the enhanced
spiral arms of M81 (left) and violent star
forming regions in M82 so energetic the galaxy
glows
in X-rays.
After repeated passes, in a few billion years only one galaxy
will remain.
From our perspective, this cosmic moment is seen through
a foreground veil of the Milky Way's stars and clouds of dust.
Faintly reflecting the foreground starlight, the
pervasive dust clouds are relatively
unexplored galactic cirrus, or
integrated
flux nebulae, only a few hundred light-years
above the plane of the Milky Way.
APOD: 2013 July 4 - M82: Starburst Galaxy with a Superwind
APOD: 2013 April 16 - Grand Spiral Galaxy M81 and Arp's Loop
APOD: 2012 June 22 - IC 2574: Coddington's Nebula
APOD: 2012 March 26 - M82: Galaxy with a Supergalactic Wind
APOD: 2012 March 13 - The M81 Galaxy Group Through the Integrated Flux Nebula
APOD: 2011 October 6 - M82: Starburst Galaxy with a Superwind
APOD: 2010 December 19 - M82: Galaxy with a Supergalactic Wind
APOD: 2010 December 9 - M81 and Arp's Loop
APOD: 2010 March 24 - Galaxy Wars: M81 versus M82
APOD: 2008 June 27 - M81: Feeding a Black Hole
APOD: 2008 May 13 - Ancient Craters of Southern Rhea
APOD: 2008 May 12 - The M81 Galaxy Group Through the Integrated Flux
Nebula
APOD: 2008 March 25 - Galaxy Wars: M81 versus M82
APOD: 2007 May 29 - Bright Spiral Galaxy M81 from Hubble
APOD: 2007 May 15 - Bright Spiral Galaxy M81 in Ultraviolet from Galex
APOD: 2007 April 27 - M81 in Ursa Major
APOD: 2007 April 5 - Asteroid and Galaxy
APOD: 2006 July 7 - Bright Galaxy M81
APOD: 2006 April 25 - M82: Galaxy with a Supergalactic Wind
APOD: 2006 April 15 - Galaxy Wars: M81 versus M82
APOD: 2006 April 14 - Smoke from the Cigar Galaxy
APOD: 2005 September 10 - Supernova Survivor
APOD: 2004 December 30 - M81 and M82: GALEX Full Field
APOD: 2004 June 1 - The Supergalactic Wind from Starburst Galaxy M82
APOD: 2004 February 12 - Supernova Survivor
APOD: 2003 November 23 - A Superwind from the Cigar Galaxy
APOD: 2002 June 20 - Bright Galaxy M81
APOD: 2001 March 12 - M82 After the Crash
APOD: 2000 April 21 - M82: Starburst in X-rays
APOD: 2000 April 4 - A Superwind from the Cigar Galaxy
APOD: 2000 February 9 - Galaxy Wars: M81 Versus M82
APOD: March 15, 1998 - Unusual M82: The Cigar Galaxy
APOD: March 14, 1998 - A Spiral Galaxy Gallery
APOD: July 26, 1997 - M81 in True Color
APOD: November 18, 1996 - Unusual M82: The Cigar Galaxy
APOD: July 14, 1996 - M81 in True Color
APOD: July 13, 1996 - M81: A Bulging Spiral Galaxy
APOD: April 9, 1996 - A Spiral Galaxy Gallery
APOD: December 3, 1995 - An X-ray Hot Supernova in M81
Explanation:
Also known as the Cigar Galaxy for its elongated visual appearance,
M82 is a starburst
galaxy with a superwind.
In fact,
through ensuing supernova explosions and
powerful winds from massive stars,
the burst of star formation in M82
is driving a prodigious outflow.
Evidence
for the superwind from the galaxy's central regions
is clear in
this
sharp telescopic snapshot.
The composite image highlights emission from
long outflow filaments of atomic hydrogen gas in reddish hues.
Some of the gas in the superwind,
enriched in heavy elements
forged in the massive stars,
will eventually escape into
intergalactic space.
Including narrow band image data in the deep exposure
has revealed a faint
feature dubbed the cap.
Perched about 35,000 light-years above the galaxy at the upper left,
the cap appears to be galactic halo material.
The material has been ionized by the superwind shock
or intense ultraviolet radiation from the young, massive stars
in the galaxy's core.
Triggered by a
Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky
Way Galaxy: big, beautiful M81.
This grand spiral galaxy lies 11.8 million light-years
away toward the northern constellation of the Great
Bear
(Ursa Major).
The deep image of the region reveals details in the bright yellow core,
but at the
same time follows fainter features along the galaxy's gorgeous blue
spiral arms and sweeping dust lanes.
It also follows the expansive, arcing feature, known
as Arp's loop, that seems to rise from the galaxy's disk at the upper right.
Studied in the 1960s, Arp's loop has been thought to be a
tidal tail,
material pulled out of M81 by gravitational interaction with its large
neighboring galaxy M82.
But a subsequent investigation
demonstrates that at least some of Arp's loop likely lies
within our own galaxy.
The loop's colors in visible and
infrared light
match the colors of pervasive
clouds of dust, relatively
unexplored
galactic cirrus only a few hundred light-years above the plane of the Milky Way.
Along with the Milky Way's stars, the dust clouds lie in
the foreground of this remarkable view.
M81's dwarf companion galaxy,
Holmberg IX,
can be seen just above the large spiral.
On the sky, this image spans about 0.5 degrees,
about the size of the Full Moon.
Explanation:
Grand spiral galaxies
often seem to get all the glory, flaunting
their young, bright, blue star clusters in beautiful,
symmetric spiral arms.
But small, irregular galaxies form stars too.
In fact
dwarf galaxy IC 2574 shows
clear evidence
of intense star forming activity in its telltale pinkish
regions of glowing hydrogen gas.
Just as in spiral galaxies, the
turbulent star-forming regions
in IC 2574 are churned by
stellar winds and
supernova explosions spewing material into the
galaxy's interstellar medium and
triggering further star formation.
A mere 12 million light-years distant, IC 2574 is part of the
M81 group of galaxies, seen toward the northern
constellation Ursa Major.
Also known as Coddington's Nebula, the lovely
island universe
is about 50,000 light-years across, discovered by
American astronomer Edwin Coddington in 1898.
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the red-glowing outwardly
expanding gas, however.
Recent evidence indicates that this gas is being
driven out by the combined emerging
particle winds of many stars, together creating a galactic
superwind..
The above photographic mosaic highlights a specific color of
red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope
towards the constellation of the Great Bear
(Ursa Major).
Explanation:
Large galaxies and faint nebulae highlight this deep image of the
M81
Group of galaxies.
First and foremost in the wide-angle 12-hour exposure is the
grand design spiral galaxy
M81, the largest galaxy
visible in the image.
M81 is
gravitationally interacting with
M82 just below it,
a big galaxy with an unusual halo of filamentary
red-glowing gas.
Around the image many other galaxies from the
M81 Group of galaxies can be seen, as well as a
lucky satellite glint
streaking across the image left.
Together with other galaxy congregates
including our Local
Group of galaxies and the
Virgo Cluster of galaxies, the
M81 Group is part of the expansive
Virgo
Supercluster of Galaxies.
This whole galaxy menagerie is seen through the faint
glow of an
Integrated
Flux Nebula, a little studied complex of diffuse gas and dust
clouds in our
Milky Way Galaxy.
Explanation:
Also known as the Cigar Galaxy for its elongated visual appearance,
M82 is a starburst galaxy
with a superwind.
In fact,
through ensuing supernova explosions and
powerful winds from massive stars,
the burst of star formation in M82
is driving the prodigous outflow of material.
Evidence
for the superwind from the galaxy's central regions
is clear in
this
sharp composite image,
based on data from small telescopes
on planet Earth.
The composite highlights emission from
filaments of atomic hydrogen gas in reddish hues.
The filaments extend for over 10,000 light-years.
Some of the gas in the superwind,
enriched in heavy elements
forged in the massive stars,
will eventually escape into intergalactic space.
Triggered by a close encounter with
nearby large galaxy M81,
the furious burst of star formation in M82 should last about
100 million years or so.
M82 is 12 million light-years distant, near the northern boundary of
Ursa Major.
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the red-glowing outwardly
expanding gas, however.
Recent evidence indicates that this gas
is being driven out by the combined emerging
particle winds of many stars, together creating a galactic
superwind..
The above photographic mosaic highlights a specific color of
red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope
towards the constellation of the Great Bear
(Ursa Major).
Explanation:
One of the brightest galaxies in planet Earth's sky and similar in size
to the Milky
Way, big, beautiful spiral M81
lies 11.8 million light-years away in the northern constellation
Ursa Major.
This
deep image of the region reveals
details in the bright yellow core, but at the
same time follows fainter features along the galaxy's gorgeous blue
spiral arms and sweeping dust lanes.
It also follows the expansive, arcing feature, known
as Arp's loop, that seems to rise from the galaxy's disk at the right.
Studied in the 1960s, Arp's loop has been thought to be a
tidal tail,
material pulled out of M81 by gravitational interaction with its large
neighboring galaxy M82.
But a recent investigation
demonstrates that much of Arp's loop likely lies within our own galaxy.
The loop's colors in visible and
infrared light
match the colors of pervasive
clouds of dust, relatively
unexplored
galactic cirrus
only a few hundred light-years above the plane of the Milky Way.
Along with the Milky Way's stars, the dust clouds lie in
the foreground of this remarkable view.
M81's dwarf companion galaxy,
Holmberg IX,
can be seen just above and left of the large spiral.
On the sky, this image spans about 0.5 degrees,
about the size of the Full Moon.
Explanation:
On the right, surrounded by blue spiral arms, is spiral galaxy
M81.
On the left, marked by red gas and dust clouds, is irregular galaxy
M82.
This stunning vista shows these two mammoth galaxies locked in
gravitational combat, as they have been for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around
M81,
resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and
colliding gas clouds so energetic the galaxy
glows
in X-rays.
In a few billion years only one galaxy
will remain.
Explanation:
This impressive
color composite
shows spiral galaxy M81 across the
electromagnetic spectrum.
It combines X-ray data (blue) from the
Chandra
Observatory,
infrared data (pink) from the
Spitzer Space Telescope, and
an ultraviolet image (purple) from the
GALEX satellite,
with a visible light (green)
Hubble image.
The inset highlights X-rays from some of M81's black holes,
including
black
holes in binary star systems with about
10 times the mass of the sun, as well as the central,
supermassive black hole of over 70 million
solar masses.
Comparing computer models of the giant black hole's energy
output to the
multiwavelength data
suggests that feeding that
monster
is relatively simple -- energy and radiation is generated
as material in the central region swirls inwards forming an
accretion disk.
In fact, the process otherwise appears to be just like the
accretion process feeding M81's stellar mass black holes,
even though the central black hole is millions of times more massive.
M81 itself is about
70,000 light-years across and only 12 million
light-years away in the northern constellation
Ursa Major.
Explanation:
Saturn's ragged moon Rhea has one of the oldest surfaces known.
Estimated as changing little in the past billion years,
Rhea shows
craters
so old they no longer appear round – their
edges have become compromised by more recent cratering.
Like Earth's Moon,
Rhea's rotation is locked on Saturn, and the
above image shows part of
Rhea's surface that always faces Saturn.
Rhea's leading surface is more highly cratered than its trailing surface.
Rhea is composed mostly of water-ice but is thought to include about 25 percent rock and metal.
The above image
was taken by the
robot Cassini spacecraft now orbiting Saturn.
Cassini swooped past
Rhea
last month
and captured the
above image
from about 350,000 kilometers away.
Rhea
spans 1,500 kilometers making it Saturn's second largest moon after
Titan.
Several
surface features on Rhea
remain unexplained including large light patches like those seen near the image top.
Explanation:
Large galaxies and faint nebulae highlight this deep image of the
M81
Group of galaxies.
First and foremost in the wide-angle 12-hour exposure is the
grand design spiral galaxy
M81, the largest galaxy
visible in the image.
M81 is
gravitationally interacting with
M82 just below it,
a big galaxy with an unusual halo of filamentary
red-glowing gas.
Around the image many other galaxies from the
M81
Group of galaxies can be seen.
Together with other galaxy congregates
including our Local
Group of galaxies and the
Virgo Cluster of galaxies,
the M81 Group is part of the expansive
Virgo
Supercluster of Galaxies.
This whole galaxy menagerie is seen through the faint
glow of an
Integrated
Flux Nebula, a little studied complex of diffuse gas and dust
clouds in our
Milky Way Galaxy.
Explanation:
On the left, surrounded by blue spiral arms, is spiral galaxy
M81.
On the right marked by red gas and dust clouds, is irregular galaxy
M82.
This stunning vista shows these two mammoth galaxies locked in
gravitational combat, as they have been for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around
M81, resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and
colliding gas clouds so energetic the galaxy
glows
in X-rays.
In a few billion years only one galaxy
will remain.
Explanation:
The Hubble Space Telescope has resolved individual stars
in a spectacular new image of nearby spiral galaxy M81.
The feat is similar to
Edwin Hubble's
historic images with the Mt. Wilson 100-inch Hooker Telescope in the 1920s that
resolved stars in neighboring galaxy
M31.
Edwin Hubble was able to use individual
Cepheid variable stars to show that M31 was not
nearby swirling gas but rather an
entire galaxy
like our
Milky Way Galaxy.
This above image in
visible light
taken by the
Hubble Space Telescope
is being used in conjunction with
images being taken in
ultraviolet by
Galex,
infrared by
Spitzer, and
X-rays with
Chandra
to study how stars have formed and died over the history M81.
Light takes about 12 million
years to reach us from M81.
M81
is visible with binoculars toward the constellation of the Great Bear
(Ursa Major).
Explanation:
Where are the hot stars in M81, one of the closest major spiral galaxies?
To help find out, astronomers took a deep image in
ultraviolet light
of the sprawling spiral with the Earth-orbiting
Galex telescope.
Hot stars emit more ultraviolet than cool stars, and are frequently associated with young
open clusters of stars and energetic
star forming regions.
Magnificent
spiral galaxy M81, slightly smaller in size to our own
Milky Way Galaxy,
shows off its young stars in its winding spiral arms in the
above image.
Less than 100 million years old, the young stars are blue in the
above false-color Galex image and seen to be well separated from the
older yellowish stars of the galactic core.
Visible above
M81 is a satellite galaxy dubbed
Holmberg IX.
Studying the unexpectedly bright ultraviolet glow of this small
irregular galaxy
may help astronomers understand how the
many satellites
of our own Milky Way Galaxy developed.
M81,
visible through a small telescope, spans about 70,000
light years
and lies about 12 million light years away toward the
constellation of the Great Bear
(Ursa Major).
Explanation:
One of the brightest galaxies in planet Earth's sky and similar in size
to the Milky Way,
big, beautiful spiral M81
lies 11.8 million light-years away
in the northern constellation Ursa Major.
This remarkably deep image
of the region reveals details in the bright
yellow core, but at the
same time follows fainter features along the galaxy's gorgeous blue
spiral arms and
sweeping dust lanes.
Above M81 lies a dwarf companion galaxy,
Holmberg IX,
sporting a large,
pinkish star-forming
region near the top.
While M81
and Holmberg IX are seen through a foreground of stars in our
own Milky Way galaxy, they
are also seen here through a much fainter complex of dust clouds.
The relatively unexplored clouds
are likely only some hundreds of light-years distant and lie high
above our galaxy's plane.
Scattered through the image, especially at the the right, the dust
clouds reflect the combined light of the
Milky Way's stars and have been dubbed
integrated
flux nebulae.
Explanation:
Apollo class
asteroid
2006 VV2
flashed past planet Earth
in late March, approaching to within 3.4 million kilometers
or about 8.8 times the Earth-Moon distance.
Due to the proximity of its orbit to Earth and its estimated
diameter of over 1 kilometer, 2006 VV2 is
classified
as a Potentially
Hazardous Asteroid.
Telescopes large and small were trained on the much
anticipated flyby,
the closest for a known asteroid of comparable
size until the year 2036.
This
composite telescopic view is from a series
of images recorded over a period of about an hour
on Mar. 28 from Vado, New Mexico.
The asteroid begins near the center of the field and tracks
down and to the left, apparently passing very near galaxy M81.
Of course,
along with
its companion galaxy M82 on the right,
M81 is really 12 million light years
away, compared to
the
asteroid's range of a mere 15 light seconds.
Explanation:
Big and beautiful
spiral galaxy M81
lies in the northern constellation
Ursa Major.
One of the
brightest galaxies in planet Earth's sky, M81 is also home
to the second brightest
supernova seen in modern times.
This superbly
detailed view
reveals M81's bright yellow nucleus, blue
spiral arms, and sweeping cosmic dust lanes with a scale comparable to
the
Milky Way.
Hinting at a disorderly past,
a remarkable dust lane actually runs straight through the
disk, below and right of the galactic center,
contrary to
M81's
other prominent
spiral features.
The errant
dust lane may be the lingering result of
a close encounter between
M81 and its smaller companion galaxy, M82.
Scrutiny of variable stars in M81 (aka NGC 3031)
has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known, was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the
red-glowing outwardly expanding gas, however.
Recent evidence indicates that this gas
is being driven out by the combined emerging
particle winds of many stars, together creating a
galactic "superwind."
The
above photographic mosaic, released yesterday to commemorate the
sixteenth anniversary of the
Hubble Space Telescope,
highlights a specific color of red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope
towards the constellation of
Ursa Major.
Explanation:
In this stunning cosmic vista,
galaxy M81 is on the left surrounded by blue spiral arms.
On the right marked by massive gas and dust clouds,
is M82.
These two mammoth galaxies have been locked in
gravitational combat
for the past billion years.
The gravity from each galaxy
dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised
density waves rippling around M81, resulting in the richness of
M81's
spiral arms.
But M81 left
M82 with
violent star forming regions and
colliding gas clouds so energetic the galaxy
glows
in X-rays.
In a few billion years only one galaxy
will remain.
Explanation:
Very bright in
infrared light,
well-known starburst galaxy M82's
popular name describes its suggestive shape
seen at visible
wavelengths -
The Cigar Galaxy.
Ironically, M82's fantastic appearance in this
Spitzer Space Telescope image
really is due to cosmic "smoke" -
the infrared emission of exented dust features blown by
stellar winds from M82's luminous, central star forming regions.
The false-color view highlights a component of dust emission from
complex carbon molecules called
polycyclic
aromatic hydrocarbons or PAHs.
PAHs are also seen in star forming regions throughout our
own, much calmer, Milky Way Galaxy and are products of
combustion on planet Earth.
Likely triggered by interactions with nearby
galaxy M81, M82's intense
star formation activity appears to be blowing out immense clouds of
dust and PAHs extending nearly 20,000 light-years both above and
below the galactic plane.
M82 is
about 12 million light-years away in the constellation
Ursa Major.
Explanation:
Beginning with a full view of beautiful spiral
galaxy M81,
follow the insets (left, bottom, then right) to
zoom in
on a real survivor.
Seen at the center of the final field on the right is a star
identified as the survivor of a cosmic cataclysm --
the supernova explosion of its companion star.
Light from the cosmic blast, likely triggered by the
core collapse of a star initially more than 10 times as massive as the Sun,
first reached Earth over 10 years ago and was
cataloged as
supernova SN 1993J.
Though the supernova itself is no longer visible,
light-echoes from
dust in the region can still be seen near the companion, the first
known survivor of a
supernova
in a binary star system.
Astronomers believe that a substantial
transfer of material
to the surviving companion star during the last few hundred years
before the stellar explosion can explain peculiarities seen
in this
supernova.
After supernova SN 1987A in the
Large Magellanic Cloud, SN 1993J
in nearby M81 is the brightest supernova seen in modern times.
Explanation:
Intriguing galaxy pair M81 and M82 shine in this
full-field view
from the orbiting GALEX observatory.
GALEX - the Galaxy Evolution
Explorer - scans the cosmos in
ultraviolet
light, a view that follows star formation
and galaxy
evolution through the Universe.
Near the bottom, magnificent spiral
galaxy M81,
similar in size to our own
Milky Way, shows off young stars in winding spiral arms.
Less than 100 million years old, the young stars are blue in
the false-color GALEX image and seen to be well
separated from the
older yellowish stars of the galactic core.
But near the top, turbulent, irregular
galaxy M82
shows the results of extreme rates of star birth and death.
Supernovae, the death explosions of massive stars,
contribute to a violent wind of material expelled from
M82's central regions.
The striking
irregular and spiral galaxy pair are located only
about 10 million light-years away in the northern constellation
Ursa Major.
Explanation:
Star formation occurs at a faster pace in
M82 --
a galaxy with about ten times the rate of massive star birth (and death) compared to our
Milky Way.
Winds from massive stars and blasts from
supernova explosions have created a billowing cloud of
expanding gas from this remarkable
starburst galaxy.
The
above scientifically color-coded image highlights the complexity and
origin of the plume by combining a wide field image from the
WIYN Telescope in
Arizona
with a smaller high-resolution image from the orbiting
Hubble Space Telescope.
M82's aspect in optical pictures has led to its popular moniker, the
Cigar Galaxy.
M82's burst of star formation was likely triggered a
mere 100 million years ago in the latest of a
series of bouts with neighboring large galaxy
M81.
Explanation:
Beginning with a full view of beautiful spiral
galaxy M81,
follow the insets (left, bottom, then right) to
zoom in
on a real survivor.
Seen at the center of the final field on the right is a star
recently identified as the survivor of a cosmic cataclysm --
the supernova explosion of its companion star.
Light from the cosmic blast, likely triggered by the
core collapse of a star initially more than 10 times as massive as the Sun,
first reached Earth over 10 years ago and was
cataloged as
supernova SN 1993J.
Though the supernova itself is no longer visible,
light-echoes from
dust in the region can still be seen near the companion, the first
known survivor of a
supernova
in a binary star system.
Astronomers believe that a substantial
transfer of material
to the surviving companion star during the last few hundred years
before the stellar explosion can explain peculiarities seen
in this
supernova.
After supernova SN 1987A in the
Large Magellanic Cloud, SN 1993J
in nearby M81 is the brightest supernova seen in modern times.
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known,
was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the
red-glowing outwardly expanding gas, however.
Recent evidence indicates that this gas
is being driven out by the combined emerging
particle winds of many stars, together creating a
galactic "superwind."
The
above recently released photograph from the new
Subaru Telescope highlights the
specific color of red light strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in visible light with a small
telescope towards the constellation of
Ursa Major.
Explanation:
Big and beautiful
spiral galaxy M81,
in the northern constellation
Ursa Major,
is one of the
brightest
galaxies visible in the skies of
planet Earth.
This superbly
detailed view
reveals its bright nucleus, grand
spiral arms and sweeping cosmic dust lanes with a scale
comparable to
the Milky Way.
Hinting at a disorderly past,
a remarkable dust lane runs straight through the
disk, below and right of the galactic center,
contrary to
M81's other
prominent
spiral features.
The errant
dust lane may be the lingering result of
a close encounter between
M81 and its smaller companion galaxy, M82.
Scrutiny of variable stars in M81 (aka NGC 3031)
has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
Explanation:
When did the Cigar Galaxy light up?
Evidence indicates how M82, the
Cigar Galaxy,
became so bright and peculiar: it
collided with neighboring galaxy
M81.
Astronomers become detectives, however,
when trying to figure out when this collision occurred.
Inspection of
this and other
Hubble Space Telescope
images now indicate massive
young
globular star clusters
were formed during the encounter.
Stars in these clusters that are
600 million years old are just now exhausting their central
hydrogen fuel,
indicating that the
Cigar Galaxy's
brightening occurred just that long ago.
M82
is located about 12 million
light years away and
visible with
binoculars towards the
constellation of Ursa Major.
The star-field
shown above spans about 10,000 light years.
Explanation:
Star formation occurs at a faster pace
in M82
-- a galaxy with about 10 times the rate of massive star birth (and
death) compared to our Milky Way.
Winds from massive stars and blasts from supernova explosions
have created the expanding
cloud of million degree gas filling the above
Chandra X-ray Observatory image of this
remarkable
starburst galaxy.
The false color image even resolves bright spots which are likely
shocked supernova remnants and
X-ray bright
binary stars.
Also observed
as a radio
galaxy and a bright celestial infrared source,
M82's
aspect in optical pictures has led to its popular
moniker, the Cigar Galaxy.
M82's burst of star formation was likely triggered a mere
100 million years ago in the latest of a
series of bouts
with another large galaxy, M81.
Explanation:
What's lighting up the Cigar Galaxy?
M82, as this
irregular galaxy is also known,
was stirred up by a
recent pass near large
spiral galaxy
M81.
This doesn't fully explain the source of the
red-glowing outwardly expanding gas, however.
Recent evidence indicates that this gas
is being driven out by the combined emerging
particle winds of many stars, together creating a
galactic "superwind."
The
above recently released photograph from the new
Subaru Telescope highlights the
specific color of red light
strongly emitted by ionized
hydrogen gas, showing detailed filaments of this gas.
The filaments extend for over 10,000
light years.
The 12-million light-year distant
Cigar Galaxy is the
brightest galaxy in the sky in infrared light, and can be seen in
visible light with a small telescope towards the constellation of
Ursa Major.
Explanation:
In the left corner, wearing a red nucleus
surrounded by blue spiral arms, is
M81.
In the right corner, sporting light stars and dark dust lanes, is
M82.
These two mammoth galaxies have been locked in
gravitational combat
for the past billion years.
The
gravity from each galaxy dramatically affects the
other during each hundred million-year pass.
Last go-round, M82's gravity likely raised circulating
density waves rippling around M81 resulting in the richness of
M81's spiral arms.
M81, though, left
M82 a messy pulp of exploded stars and
colliding gas so violent it
emits bright X-rays.
In both galaxies, colliding gas has created a recent abundance of
bright new stars.
In a few billion years only one galaxy will remain.
Explanation:
Something strange happened to this galaxy, but what?
M82
is a nearby galaxy in the group of galaxies dominated by itself,
M81, and NGC 3077.
M82 is thought by some to be limping away from a
close encounter with M81. This galactic collision might have stirred up the
inner stars and gas in M82, causing the unusual dark lanes of
dust
visible in the above photograph.
M82
is a starburst galaxy with a very
active center containing star clusters far brighter than any in our own
Milky Way Galaxy.
Explanation:
A progression of beautiful spiral galaxies is illustrated above with three
photographs from NASA's Ultraviolet Imaging Telescope (UIT).
Flying above the Earth's obscuring layer of atmosphere on the
Space Shuttle Columbia during
the Astro-1 mission in 1990,
UIT's cameras were able to image these distant spirals in the ultraviolet
light produced by hot, young stars.
These bright stars, newly condensed from
gas and dust clouds, give away the location of the spiral arms
they are born in.
Because they are massive (many times the mass of the
Sun), they are shortlived.
Dying and fading before they move too far from their
birth place they make excellent tracers of spiral structure.
From left to right the galaxies are known as M33, M74, and M81 and
have progressively more tightly wound spiral arms.
Astronomers would
classify these as Scd, Sc, and Sb type spirals using a
galaxy classification scheme first worked out by
Edwin Hubble.
Explanation:
Here's is a spiral galaxy in true colors.
Previously, M81 was shown in
two colors only, but
M81's real
colors are just as dramatic. In
the above
picture, note how blue
the spiral arms are - this indicates the presence of
hot young stars and
on-going star formation.
Also note the yellow hue of the nucleus, indicating
am ancient population of stars many billions of years old.
M81
is actually a dominant member of a group of galaxies which includes
M82
and several other galaxies. Unlike our
Local Group of galaxies, large
galaxies in
the M81
group are actually colliding. It is possible that
M81's interaction with M82 create the
density
waves which generate M81's
spiral structure.
Explanation: Something strange happened to this galaxy,
but what? M82
is a nearby galaxy in the group of galaxies
dominated by itself, M81, and NGC 3077.
M82 is thought by some to be limping away from a close encounter
with M81.
This galactic collision
might have stirred up the inner stars and gas in M82,
causing the unusual dark lanes of dust
visible in the above photograph. M82
is a starburst galaxy with a very
active center containing star clusters far brighter
than any in our own Milky Way Galaxy.
Explanation:
Here's what a spiral galaxy REALLY looks like.
Yesterday, M81 was shown in
two colors only, but here we see
M81 at its most
colorful. In
the above
picture, note how blue
the spiral arms are - this indicates the presence of
hot young stars and
on-going star formation.
Also note the yellow hue of the nucleus, possibly
designating a population of older stars many billions of years old.
M81
is actually a dominant member of a group of galaxies which includes
M82
and several other galaxies. Unlike our
Local Group of galaxies, large
galaxies in
the M81
group are actually colliding. It is possible that
M81's interaction with M82 create the
density
waves which generate M81's
spiral structure.
Explanation:
Few stars are still forming in the old giant spiral galaxy M81. The blue
regions
in this picture - representing
ultraviolet light -
highlight regions of bright
young stars and star formation and appear rare than in
M74 and
M33. The
red regions - representing the visible light - show a large population of
older, less massive stars.
M81
is therefore classified as
spiral galaxy
type "Sab" on the
Hubble Sequence of Galaxies. One distinguishing feature
of these types of galaxies is the relatively large central bulge
surrounding the center of the galaxy. A massive
density wave circulates
around the center of spiral galaxies. It is not well understood why the
bulge of
M81
glows as bright as it does in ultraviolet light. Speculation
includes that this may be due to hot evolved stars such as those found in
the ancient globular cluster
Omega Centauri.
Explanation:
A progression of beautiful spiral galaxies is illustrated above with three
photographs from NASA's Ultraviolet Imaging Telescope (UIT).
Flying above the Earth's obscuring layer of atmosphere on the
Space Shuttle Columbia during
the Astro-1 mission in 1990,
UIT's cameras were able to image these distant spirals in the ultraviolet
light produced by hot, young stars.
These bright stars, newly condensed from
gas and dust clouds, give away the location of the spiral arms
they are born in.
Because they are massive (many times the mass of the
Sun), they are shortlived.
Dying and fading before they move too far from their
birth place they make excellent tracers of spiral structure.
From left to right the galaxies are known as M33, M74, and M81 and
have progressively more tightly wound spiral arms. Astronomers would
classify these as Scd, Sc, and Sb type spirals using a
galaxy classification scheme first worked out by
Edwin Hubble.
Explanation:
In 1993, a star in the galaxy
M81 exploded.
Above is a picture of the hot material ejected by this
supernova explosion.
The picture was taken in
X-rays with the
Advanced
Satellite for Cosmology and Astrophysics
(ASCA).
Since M81 is a relatively nearby galaxy, it can be
examined in close detail by observatories on or near the
Earth. Since the
Earth's atmosphere protects the surface from
interstellar X-radiation, the
above
photo was taken from space. Studying
the nature and distribution of the X-rays has allowed astronomers to
determine the composition and temperature of the expanding supernova gas.
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