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Astronomy Picture of the Day |
APOD: 2022 February 18 - Three Clusters in Puppis
Explanation:
Galactic or
open star clusters
are young.
The swarms of stars are born together near the plane of the Milky Way,
but their numbers
steadily dwindle
as cluster members are
ejected by galactic tides and gravitational interactions.
Caught in
this telescopic frame
over three degrees across are three
good examples of galactic star clusters,
seen toward the southern sky's nautical constellation
Puppis.
Below and left, M46 is
some 5,500 light-years in the distance.
Right of center
M47 is
only 1,600 light-years away and
NGC 2423 (top) is about 2500 light-years distant.
Around 300 million years young M46
contains a few hundred stars in a region about 30 light-years
across.
Sharp eyes can spot a planetary nebula,
NGC 2438,
at about 11 o'clock against the M46 cluster stars.
But that nebula's
central star
is billions of years old, and
NGC 2438 is likely a foreground object only by chance
along the line of sight to youthful M46.
Even younger, aged around 80 million years, M47 is a
smaller and looser star cluster spanning about 10 light-years.
Star cluster NGC 2423 is pushing about 750 million years
in age though.
NGC 2423 is known to harbor an extrasolar planet,
detected orbiting one
of its red giant stars.
APOD: 2012 April 3 - M46 and M47: Star Clusters Young and Old
Explanation:
Many stars form in
clusters.
Galactic or
open star
clusters are relatively young
swarms of bright stars
born
together near the plane of our Milky Way Galaxy.
Separated by about a degree on the sky, two
nice examples are M46
(upper left) 5,400 light-years in the distance
and M47
(lower right) only 1,600 light-years away toward
the nautical constellation
Puppis.
Around 300 million years
young M46
contains a few hundred stars in a region about 30 light-years
across.
Aged 80 million years,
M47 is a
smaller but looser cluster
of about 50 stars spanning 10 light-years.
But
this portrait of stellar youth also contains
an ancient
interloper.
The small, colorful patch of glowing gas in
M46 is actually
the planetary nebula
NGC 2438 - the
final phase in the life of a sun-like star billions
of years old.
NGC
2438 is estimated to be only 3,000 light-years distant
and likely represents a foreground object, only by chance appearing
along our line of sight to youthful M46.
APOD: 2011 October 7 - The Comet Hartley 2 Cruise
Explanation:
Early last November, small but active Comet Hartley 2
(103/P Hartley) became the
fifth comet
imaged close-up by a
spacecraft
from planet Earth.
Still cruising
through
the solar system with a 6 year
orbital period, Hartley 2 is making
astronomical headlines again.
New
Herschel
Space Observatory measurements indicate that the water
found in this comet's thin atmosphere or coma has the same ratio
of the hydrogen
isotope
deuterium (in heavy water)
as the oceans of our fair planet.
Hartley 2 originated in the
distant Kuiper Belt,
a region beyond the orbit of Neptune that is a reservoir
of icy cometary bodies and dwarf planets.
Since the ratio of deuterium is related to the solar system
environment where the comet formed, the Herschel results
indicate that Kuiper Belt comets could have
contributed substantial amounts of water to Earth's oceans.
Comet Hartley 2 appears in
this starry skyscape from last November
sporting a tantalizing greenish coma appropriately sailing through the
nautical
constellation Puppis.
Below the comet are open star clusters M47 (right) and
M46 (left).
APOD: 2010 December 2 - Hartley 2 Star Cluster Tour
Explanation:
Early in November, small
but active
Comet Hartley 2 (103/P Hartley) became the
fifth comet
imaged close-up by a
spacecraft
from planet Earth.
Continuing its own
tour
of the solar system with a 6 year
orbital period, Hartley 2 is
now appearing in the
nautical
constellation Puppis.
Still a target for binoculars or small telescopes from dark sky
locations, the comet is captured in this composite image
from November 27, sharing the rich 2.5 degree wide
field of view
with some star clusters well known
to earthbound skygazers.
Below and right of the comet's alluring green coma lies
bright M47,
a young open star cluster some 80 milion years old,
about 1,600 light-years away.
Below and left open cluster
M46 is older,
around 300 million years of age, and 5,400 light-years distant.
Hartley 2's short, faint tail even extends
up and right
toward another fainter star cluster in the scene, NGC 2423.
On November 27, Comet Hartley 2 was about 2.25
light-minutes from Earth.
Sweeping toward
the bottom of this field, by November 28 the
comet's path had carried it between M46 and M47.
APOD: 2006 September 10 - Star Clusters Young and Old
Explanation:
Many stars form in clusters.
Galactic or
open star
clusters are relatively young
swarms of bright stars
born
together near the plane of our Milky Way Galaxy.
Separated by about a degree on the sky, two
nice
examples are M46
(upper left) 5,400 light-years in the distance
and M47
(lower right) only 1,600 light-years away toward
the nautical constellation
Puppis.
Around 300 million years
young M46
contains a few hundred stars in a region about 30 light-years
across.
Aged 80 million years,
M47 is a
smaller but looser cluster
of about 50 stars spanning 10 light-years.
But
this
portrait of stellar youth also contains
an ancient interloper.
The small, colorful patch of glowing gas in M46 is actually
the planetary nebula NGC 2438 - the
final phase in the life of a sun-like star billions
of years old.
NGC
2438 is estimated to be only 3,000 light-years distant
and likely represents a foreground object, only by chance appearing
along our line of sight to youthful M46.
APOD: 2005 August 4 - Stars Young and Old
Explanation:
Galactic or
open star
clusters are relatively young
swarms of bright stars
born
together near the plane of our Milky Way Galaxy.
Separated by about a degree on the sky, two
nice
examples are M46
(upper left) 5,400 light-years in the distance
and M47
(lower right) only 1,600 light-years away toward
the nautical constellation
Puppis.
Around 300 million years
young M46
contains a few hundred stars in a region about 30 light-years
across.
Aged 80 million years,
M47 is a
smaller but looser cluster
of about 50 stars spanning 10 light-years.
But
this
portrait of stellar youth also contains
an ancient interloper.
The small, colorful patch of glowing gas in M46 is actually
the planetary nebula NGC 2438 - the
final phase in the life of a sun-like star billions
of years old.
NGC
2438 is estimated to be only 3,000 light-years distant
and likely represents a foreground object, only by chance appearing
along our line of sight to youthful M46.