The SpaceAppreciationSociety
Space - New Horizons And Distant Worlds
Bullet Cluster 1E 0657-56
Composite Credit: X-ray: NASA/CXC/CfA/ M.Markevitch et al.;
Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/ D.Clowe et al.
Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.
The matter in galaxy cluster 1E 0657-56, fondly known
as the "bullet cluster", is shown in this composite image.
A mere 3.4 billion light-years away, the bullet cluster's
individual galaxies are seen in the optical image data,
but their total mass adds up to far less than the mass
of the cluster's two clouds of hot x-ray emitting gas
shown in red. Representing even more mass than the
optical galaxies and x-ray gas combined, the blue hues
show the distribution of dark matter in the cluster.
Otherwise invisible to telescopic views, the dark matter
was mapped by observations of gravitational lensing of
background galaxies. In a text book example of a shock
front, the bullet-shaped cloud of gas at the right was
distorted during the titanic collision between two galaxy
clusters that created the larger bullet cluster itself.
But the dark matter present has not interacted with
the cluster gas except by gravity. The clear separation
of dark matter and gas clouds is considered direct
evidence that dark matter exists.
Galaxies Away
Credit: NASA, ESA, Hubble Heritage Team (STScI / AURA)
Acknowledgment: J. Blakeslee (Washington State University)
This stunning group of galaxies is far, far away - about 450 million
light-years from planet Earth - cataloged as galaxy cluster Abell S0740.
Dominated by the cluster's large central elliptical galaxy (ESO 325-G004),
this sharp Hubble view takes in a remarkable assortment of galaxy shapes
and sizes with only a few spiky foreground stars scattered through the field.
The giant elliptical galaxy spans over 100,000 light years and contains about
100 billion stars, comparable in size to our own spiral Milky Way. The Hubble
data reveal a wealth of detail in even these distant galaxies, including
magnificent arms and dust lanes, star clusters, ring structures, and
gravitational lensing arcs.
Galaxy Group Hickson 44
Credit & Copyright: MASIL Imaging Team
Galaxies, like stars, frequently form groups. A group of galaxies
is a system containing more than two galaxies but less than the tens or
hundreds typically found in a cluster of galaxies. A most notable example
is the Local Group of Galaxies, which houses over 30 galaxies including our
Milky Way, Andromeda, and the Magellanic Clouds. Pictured above is nearby
compact group Hickson 44. This group is located about 60 million light-years
away toward the constellation of Leo. Also known as the NGC 3190 Group,
Hickson 44 contains several bright spiral galaxies and one bright elliptical galaxy
on the upper left. The bright source on the upper right is a foreground star.
Many galaxies in Hickson 44 and other compact groups are either slowly merging
or gravitationally pulling each other apart.
Supernova Remnant E0102
Credit: Hubble Heritage Team, ESA, NASA
Supernova Remnant E0102 from Hubble:
It's the blue wisp near the bottom that's the remnant of
a tremendous recent supernova explosion. The large pink
structure looming to the upper right is part of N76, a large
star forming region in our neighboring Small Magellanic Cloud
(SMC) galaxy. The supernova remnant wisp, with full
coordinate name 1E0102.2-7219 and frequently abbreviated
as E0102, also lies in the SMC, about 50 light years away
from N76. The above image is a composite of several images
taken by the Hubble Space Telescope. E0102 is of research
interest because we see it as it appeared only 2,000 years
after its explosion. Examination of E0102 therefore gives clues
about how an enigmatic supernova works and what materials
it dispersed into the surrounding interstellar medium.
The Majestic Sombrero Galaxy
Credit: NASA/ESA and The Hubble Heritage Team (STScI/AURA)
NASA's Hubble Space Telescope has trained its razor-sharp eye on one of the universe's most stately and photogenic galaxies, the Sombrero galaxy, Messier 104 (M104). The galaxy's hallmark is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. As seen from Earth, the galaxy is tilted nearly edge-on. We view it from just six degrees north of its equatorial plane. This brilliant galaxy was named the Sombrero because of its resemblance to the broad rim and high-topped Mexican hat.
At a relatively bright magnitude of +8, M104 is just beyond the limit of naked-eye visibility and is easily seen through small telescopes. The Sombrero lies at the southern edge of the rich Virgo cluster of galaxies and is one of the most massive objects in that group, equivalent to 800 billion suns. The galaxy is 50,000 light-years across and is located 28 million light-years from Earth.
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What precisely is a Light Year ?
A light year is the distance between two points in space that it would take light to travel when the distance between the two points in time are one year. It is a measure of distance, not time. It is the total distance that a beam of light, moving in a straight line, travels in one year. As light is fast, it travels at 186,000 miles per second or 299,792,458 metres per second, a light year is a long way! In a year there are 60 x 60 x 24 x 365.2425 = 31,556,952 seconds. So how far is a light year? Answer: 9,460,536,207,068,016 metres or 5,865,696,000,000 million miles! ( Nearly 6 trillion miles ). Now that you know what the distance is that light travels in one year you can also know the distance between objects in the universe. The closest star to us is about four light years away. This means that it is 23,462,784,000,000 miles away. How about this: the edge of the universe is about 15 billion light years away from us!
NGC 5905 and 5908
Credit & Copyright: Stefan Seip
These two beautiful galaxies, NGC 5905 (left) and NGC 5908
lie about 140 million light-years distant in the northern constellation Draco.
Separated by about 500,000 light-years, the pair are actually both spiral
galaxies and nicely illustrate the striking contrasts in appearance possible
when viewingspirals from different perspectives. Seen face-on, NGC 5905
is clearly a spiral galaxy with bright star clusters tracing arms that wind
outward from a prominent central bar. Oriented edge-on to our view,
the spiral nature of NGC 5908 is revealed by a bright nucleus and dark
band of obscuring dust characteristic of a spiral galaxy's disk. In fact,
NGC 5908 is similar in appearance to the well studied edge-on spiral
galaxy M104 - The Sombrero Galaxy.
Spiral Galaxy NGC 7331 and Beyond
Credit & Copyright: R. Jay GaBany (Cosmotography.com)
Spiral galaxy NGC 7331 is often touted as an analog to
our own Milky Way. About 50 million light-years distant
in the northern constellation Pegasus, NGC 7331 was
recognized early on as a spiral nebula and is actually one
of the brighter galaxies not included in Charles Messier's
famous 18th century catalog. Since the galaxy's disk is
inclined to our line-of-sight, deep telescopic exposures
often result in an image that evokes a strong sense of
depth. The effect is further enhanced in this well-framed
view by the galaxies that lie beyond this beautiful island universe.
The background galaxies are about one tenth
the apparent size of NGC 7331 and so lie roughly ten
times farther away.
The Pleiades Star Cluster
( Credit: NASA/ESA/AURA/Caltech.)
The Pleiades are an open cluster dominated by hot blue stars surrounded by reflection nebulosity The Pleiades (also known as M45 or the Seven Sisters) is an open cluster in the constellation of Taurus. It is among the nearest to the Earth of all open clusters, probably the best known and certainly the most striking to the naked eye.
Accurate knowledge of the distance to the cluster is very important in astronomy as it is a crucial first step on the cosmic distance ladder, the calibration of the distance scale of the whole universe. The Hipparcos satellite caused consternation when it measured a distance to the cluster which was 10% smaller than most previous measurements, but it was later found to have suffered from a systematic error when observing the Pleiades which led to the discrepancy. The cluster is now known to lie at a distance of about 135 parsecs (440 light years).
The cluster is dominated by hot blue stars, which have formed within the last 100 million years. Dust that forms faint reflection nebulosity around the brightest stars was thought at first to be left over from the formation of the cluster but is now known to be an unrelated dust cloud that the stars are currently passing through. Astronomers estimate that the cluster will survive for about another 250 million years, after which time it will have dispersed due to gravitational interactions with the spiral arms of the galaxy and giant molecular clouds.
Orion's Horsehead Nebula
Credit & Copyright: Ryan Steinberg & Family, Adam Block,
NOAO, AURA, NSF
The Horsehead Nebula is one of the
most famous nebulae on the sky. It is visible as the dark indentation
to the red emission nebula seen above and to the right of center in
the above photograph. The brightstar on the left is located in the
belt of the familiar constellationof Orion. The horse-head feature is dark
because it is really an opaque dust cloud which lies in front of the bright
red emissionnebula. Like clouds in Earth's atmosphere, this cosmic
cloud hasassumed a recognizable shape by chance. After many thousands
of years, the internal motions of the cloud will alter its appearance.
The emission nebula's red color is caused by electrons recombining
with protons to form hydrogen atoms. Also visible in the picture
are blue reflection nebulae, which preferentially reflect the blue
light from nearby stars.
The Great Nebula in Orion
Credit & Copyright: Jon Christensen
M42: Wisps of the Orion Nebula
The Great Nebula in Orion, an immense, nearby starbirth region,
is probably the most famous of all astronomical nebulas. Here, glowing gas
surrounds hot young stars at the edge of an immense interstellar molecular
cloud only 1500 light-years away. In the above deep image, faint wisps and
sheets of dust and gas are particularly evident. The Great Nebula in Orion
can be found with the unaided eye just below and to the left of the easily
identifiable belt of three stars in the popular constellation Orion. In addition
to housing a bright open cluster of stars known as the Trapezium, the Orion
Nebula contains many stellar nurseries. These nurseries contain hydrogen gas,
hot young stars, proplyds, and stellar jets spewing material at high speeds.
Also known as M42, the Orion Nebula spans about 40 light years and is located
in the same spiral arm of our Galaxy as the Sun.
Alnitak, Alnilam, Mintaka
Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator
Color Composite: Davide De Martin (Skyfactory)
Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west
(left to right) along the diagonal in this gorgeous cosmic vista. Otherwise
known as the Belt of Orion, these three blue supergiant stars are hotter
and much more massive than the Sun. They lie about 1,500 light-years
away, born of Orion's well-studied interstellar clouds. In fact, clouds of
gas and dust adrift in this region have intriguing and some surprisingly
familiar shapes, including the dark Horsehead Nebula and Flame Nebula
near Alnitak at the lower left. The famous Orion Nebula itself lies off the
bottom of this star field that covers an impressive 4.4x3.5 degrees on
the sky. The color picture was composited from digitized black and white
photographic plates recorded through red and blue astronomical filters,
with a computer synthesized green channel. The plates were taken
using the Samuel Oschin Telescope, a wide-field survey instrument at
Palomar Observatory, between 1987 and 1991.
V838 Monocerotis
Credit: NASA, ESA, and H. Bond (STScI)
38 Mon: Echoes from the Edge.
Variable star V838 Monocerotis lies near the edge of
our Milky Way Galaxy, about 20,000 light-years from the Sun. Still,
ever since a sudden outburst was detected in January 2002, this
enigmatic star has taken the center of an astronomical stage. As
astronomers watch, light from the outburst echoes across pre-existing
dust shells around V838 Mon, progressively illuminating ever more
distant regions. This stunning image of swirls of dust surrounding
the star was recorded by the Hubble Space Telescope in September
of this year. The picture spans about 14 light-years. Astronomers
expect the expanding echoes to continue to light up the dusty
environs of V838 Mon for at least the rest of the current decade.
Researchers have now found that V838 Mon is likely a young binary
star, but the cause of its extraordinary outburst remains a mystery.
MWC 922: The Red Square Nebula
Credit & Copyright: Peter Tuthill (Sydney U.) and James Lloyd (Cornell)
What could cause a nebula to appear square? No one is quite sure. The
hot star system known as MWC 922, however, appears to be imbedded
in a nebula with just such a shape. The above image combines infrared
exposures from the Hale Telescope on Mt. Palomar in California, and the
Keck-2 Telescope on Mauna Kea in Hawaii. A leading progenitor hypothesis
for the square nebula is that the central star or stars somehow expelled
cones of gas during a late developmental stage. For MWC 922, these
cones happen to incorporate nearly right angles and be visible from the
sides. Supporting evidence for the cone hypothesis includes radial spokes
in the image that might run along the cone walls. Researchers speculate
that the cones viewed from another angle would appear similar to the
gigantic rings of supernova 1987A, possibly indicating that a star in MWC 922
might one day itself explode in a similar supernova.
Dust and the Helix Nebula
Credit: NASA, JPL-Caltech, Kate Su (Steward Obs, U. Arizona) et al.
Dust makes this cosmic eye look red. The eerie Spitzer Space
Telescope image shows infrared radiation from the well-studied Helix Nebula
(NGC 7293) a mere 700 light-years away in the constellation Aquarius. The
two light-year diameter shroud of dust and gas around a central white
dwarf has long been considered an excellent example of a planetary nebula,
representing the final stages in the evolution of a sun-like star. But the
Spitzer data show the nebula's central star itself is immersed in a surprisingly
bright infrared glow. Models suggest the glow is produced by a dust debris
disk. Even though the nebular material was ejected from the star many
thousands of years ago, the close-in dust could be generated by collisions
in a reservoir of objects analogous to our own solar system's Kuiper Belt
or cometary Oort cloud. Formed in the distant planetary system, the
comet-like bodies have otherwise survived even the dramatic late stages
of the star's evolution.
The Eagle Nebula in Infrared
Credit: NASA/JPL-Caltech/N. Flagey (IAS/SSC) & A. Noriega-Crespo
(SSC/Caltech) In visible light, the whole thing looks like an eagle.
The region was captured recently in unprecedented detail in infrared
light by the robotic orbiting Spitzer Space Telescope (SSC). Shown above,
the infrared image allows observers to peer through normally opaque dust
and so better capture the full complexity of the Eagle Nebula star forming
region. In particular, the three famous pillars near the image center are
seen bathed in dust likely warmed by a supernova explosion. The warm
dust is digitally assigned the false color of red. Also visible, near the
bottom of the image, is ten light-year long pillar sometimes dubbed the
Fairy of Eagle Nebula. The greater Eagle emission nebula, tagged M16,
lies about 6500 light years away, spans about 20 light-years, and is visible
with binoculars toward the constellation of Serpens.
The Crab Nebula
Credit: NASA - X-ray: CXC, J.Hester (ASU) et al.;
Optical: ESA, J.Hester and A.Loll (ASU); Infrared: JPL-Caltech, R.Gehrz (U. Minn)
The Crab Nebula is cataloged as M1, the first object on Charles Messier's
famous list of things which are not comets. In fact, the Crab is now known
to be a supernova remnant, expanding debris from the death explosion
of a massive star. This intriguing false-color image combines data from
space-based observatories, Chandra, Hubble, and Spitzer, to explore the
debris cloud in x-rays (blue-purple), optical (green), and infrared (red) light.
One of the most exotic objects known to modern astronomers, the Crab
Pulsar, a neutron star spinning 30 times a second, is the bright spot near
picture center. Like a cosmic dynamo, this collapsed remnant of the stellar
core powers the Crab's emission across the electromagnetic spectrum.
Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away
in the constellation Taurus.
Massive Stars in Open Cluster Pismis 24
Credit: NASA, ESA and J. M. Apellániz (IAA, Spain).
How massive can a normal star be? Estimates made from
distance, brightness and standard solar models had given one star in
the open cluster Pismis 24 over 200 times the mass of our Sun,
making it a record holder. This star is the brightest object located
just to the right of the gas front in the above image. Close inspection
of images taken recently with the Hubble Space Telescope, however,
have shown that Pismis 24-1 derives its brilliant luminosity not from a
single star but from three at least. Component stars would still remain
near 100 solar masses, making them among the more massive stars
currently on record. Toward the image left, stars are still forming in
the associated emission nebula NGC 6357, including several that appear
to be breaking out and illuminating a spectacular cocoon.
Helix Nebula
Credit: NASA and The Hubble Heritage Team (STScI/AURA)
The Helix Nebula (also known as NGC 7293). It is one of the closest planetary nebulae to Earth and was discovered by Karl Ludwig Harding before 1824. The Helix Nebula is an example of a planetary nebula created at the end of the life of a Sun-like star. The outer gases of the star expelled into space appear from our vantage point as if we are looking down a helix. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic that it causes the previously expelled gas to fluoresce. Helix lies about 650 light-years away towards the constellation of Aquarius and spans about 2.5 light-years. Recent pictures of Helix are a composite of newly released images from the ACS instrument on the Hubble Space Telescope and wide-angle images from the Mosaic Camera on the WIYN 0.9-m Telescope at Kitt Peak National Observatory.
The Helix has often been referred to as the Eye of God, in Internet Folklore since about 2003, and also as the "Eye of Sauron" due to its resemblance to said object in the "Lord of the Rings" movie trilogy.
From Wikipedia, the free encyclopedia
NGC 602 and Beyond
Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA)
- ESA/Hubble Collaboration
Near the outskirts of the Small Magellanic Cloud, a satellite galaxy
some 200 thousand light-years distant, lies 5 million year young
star cluster NGC 602. Surrounded by natal gas and dust, NGC 602
is featured in this stunning Hubble image of the region. Fantastic
ridges and swept back shapes strongly suggest that energetic
radiation and shock waves from NGC 602's massive young stars
have eroded the dusty material and triggered a progression of
star formation moving away from the cluster's center. At the
estimated distance of the Small Magellanic Cloud, the picture
spans about 200 light-years, but a tantalizing assortment of
background galaxies are also visible in the sharp Hubble view.
The background galaxies are hundreds of millions of light-years
or more beyond NGC 602.
Stars, Dust and Nebula in NGC 2170
Credit & Copyright: Russell Croman (Russell Croman Astrophotography)
When stars form, pandemonium reigns. A textbook case
is the star forming region NGC 2170. Visible above are red glowing
emission nebulas of hydrogen, blue reflection nebulas of dust, dark
absorption nebulas of dust, and the stars that formed from them.
The first massive stars formed from the dense gas will emit energetic
light and winds that erode, fragment, and sculpt their birthplace.
And then they explode. The resulting morass is often as beautiful
as it is complex. After tens of millions of years, the dust boils away,
the gas gets swept away, and all that is left is a naked open cluster of stars.
Central IC 1805
Credit & Copyright: Ken Crawford (Rancho Del Sol Observatory)
Cosmic clouds seem to form fantastic shapes in the central
regions of emission nebula IC 1805. Of course, the clouds are sculpted
by stellar winds and radiation from massive hot stars in the nebula's
newborn star cluster (aka Melotte 15). About 1.5 million years young,
the cluster stars appear in this colorful skyscape, along with dark dust
clouds silhouetted against glowing atomic gas. A composite of narrow
band telescopic images, the view spans about 15 light-years and shows
emission from hydrogen in green, sulfur in red, and oxygen in blue hues.
Wider field images reveal that IC 1805's simpler, overall outline suggests
its popular name - The Heart Nebula. IC 1805 is located about 7,500 light
years away toward the constellation Cassiopeia
Magellanic Gemstones In The Southern Sky
Hubble has captured the most detailed image to date of the open star cluster NGC 290 in the Small Magellanic Cloud. The image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope show a myriad of stars in crystal clear detail. The brilliant open star cluster, NGC 290, is located about 200,000 light-years away and is roughly 65 light-years across.
Credit: NASA/ESA and The Hubble Heritage Team (STScI/AURA)
The Milky Way Over Utah
Credit & Copyright: Wally Pacholka (Astropics.com)
Explanation: If sometimes it appears that the entire Milky
Way Galaxy is raining down on your head, do not despair.
It happens twice a day. As the Sun rises in the East,
wonders of the night sky become less bright than the
sunlight scattered by our own Earth's atmosphere, and
so fade from view. They will only rotate back into view
when the Earth again eclipses our bright Sun at dusk.
This battle between heaven and Earth was captured
dramatically over a rock formation at Capitol Reef National
Park Utah, USA in 2003 May. Dark dust, millions of stars,
and bright glowing red gas highlight the plane of our
Milky Way Galaxy, which lies on average thousands of
light years behind Earth's mountains.
The Antennae Galaxies in Collision
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration
Acknowledgment: B. Whitmore (Space Telescope Science Institute) et al.
Two galaxies are squaring off in Corvus and here are the latest pictures.
When two galaxies collide, however, the stars that compose them usually
do not. This is because galaxies are mostly empty space and, however
bright, stars only take up only a small amount of that space. During the
slow, hundred million year collision, however, one galaxy can rip the other
apart gravitationally, and dust and gas common to both galaxies does collide.
In the above clash of the titans, dark dust pillars mark massive molecular
clouds are being compressed during the galactic encounter, causing the
rapid birth of millions of stars, some of which are gravitationally bound
together in massive star clusters.
A Pelican in the Swan
Image Data: Digitized Sky Survey, Color Composite: Charles Shahar
The Pelican Nebula lies about 2,000 light-years away in
the high flying constellation Cygnus, the Swan. Also known as IC
5070, this cosmic pelican is appropriately found just off the "east
coast" of the North America Nebula (NGC 7000), another surprisingly
familiar looking emission nebula in Cygnus. The Pelican and North
America nebulae are part of the same large and complex star forming
region, almost as nearby as the better-known Orion Nebula. From our
vantage point, dark dust clouds (upper left) help define the
Pelican's eye and long bill, while a bright front of ionized gas
suggests the curved shape of the head and neck. Based on digitized
black and white images from the Samuel Oschin Telescope at Palomar
Observatory, this striking synthesized color view includes two
bright foreground stars and spans about 30 light-years at the
estimated distance of the Pelican Nebula
Star Cluster R136 Bursts Out
Credit: NASA, J. Trauger (JPL), J. Westphal (Caltech)
In the center of star-forming region 30 Doradus lies a huge
cluster of the largest, hottest, most massive stars known. These stars,
known as the star cluster R136, and part of the surrounding nebula are
captured here in this gorgeous visible-light image from the Hubble Space
Telescope. Gas and dust clouds in 30 Doradus, also known as the Tarantula
Nebula, have been sculpted into elongated shapes by powerful winds and
ultraviolet radiation from these hot cluster stars. The 30 Doradus Nebula lies
within a neighboring galaxy, the Large Magellanic Cloud, located a mere
170,000 light-years away.
The Colorful Clouds of Rho Ophiuchi
Credit & Copyright: Jim Misti and Steve Mazlin, (acquisition), Robert Gendler (processing)
This stunning mosiac of the sky around bright stars Antares
(Alpha Scorpii) and Rho Ophiuchi reveals spectacular colors
in a cosmic starscape. Near the top, Rho Ophiuchi and nearby
stars are immersed in blue reflection nebulae - dust clouds
that shine primarily by reflected starlight. Cool supergiant
star Antares (lower left) is itself shedding the material that
reflects the evolved star's yellowish hue. Characteristic of
star forming regions, the telltale red emission from hydrogen
gas also permeates the view along with dark, obscuring dust
clouds seen in silhouette against the background stars and
brighter nebulosities. About 500 light-years away, the Rho
Ophiuchi star clouds, are well in front of the nearby
The wide view spans about 6 degrees on the sky.
NGC 1365: Majestic Island Universe
Credit & Copyright: SSRO-South (R.Gilbert,D.Goldman,J.Harvey,D.Verschatse)
- PROMPT (D.Reichart)
Barred spiral galaxy NGC 1365 is truly a majestic island universe
some 200,000 light-years across. Located a mere 60 million
light-years away toward the chemical constellation Fornax,
NGC 1365 is a dominant member of the well-studied Fornax
galaxy cluster. This impressively sharp color image shows intense
star forming regions at the ends of the bar and along the spiral
arms, as well as details of dust lanes cutting across the galaxy's
bright core. At the core lies a supermassive black hole. Astronomers
think NGC 1365's prominent bar plays a crucial role in the galaxy's
evolution, drawing gas and dust into a star-forming maelstrom
and ultimately feeding material into the central black hole.
M81 in Ursa Major
Credit & Copyright: Tony Hallas
One of the brightest galaxies in planet Earth's sky and similarn size to the Milky Way,
big, beautiful spiral M81 lies 11.8 million light-yearsaway in the northern constellation
Ursa Major. This remarkably deep imageof 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.
Spiral Galaxy NGC 1512
Credit: NASA, ESA, and D. Maoz (Tel-Aviv University and Columbia University)
In this view of the center of the magnificent barred spiral galaxy NGC 1512,
NASA Hubble Space Telescope’s broad spectral vision reveals the galaxy at all
wavelengths from ultraviolet to infrared. The colors (which indicate differences
in light intensity) map where newly born star clusters exist in both "dusty"
and "clean" regions of the galaxy. This color-composite image was created
from seven images taken with three different Hubble cameras: the Faint
Object Camera (FOC), the Wide Field and Planetary Camera 2 (WFPC2),
and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).
NGC 1512 is a barred spiral galaxy in the southern constellation of Horologium.
Located 30 million light-years away, relatively "nearby" as galaxies go, it is bright
enough to be seen with amateur telescopes. The galaxy spans 70,000 light-years,
nearly as much as our own Milky Way galaxy. The galaxy’s core is unique for its stunning
2,400 light-year-wide circle of infant star clusters, called a "circumnuclear" starburst ring.
Starbursts are episodes of vigorous formation of new stars and are found in a variety of
galaxy environments. Taking advantage of Hubble’s sharp vision, as well as its unique
wavelength coverage, a team of Israeli and American astronomers performed one of
the broadest and most detailed studies ever of such star-forming regions. The results,
which will be published in the June issue of the Astronomical Journal, show that in NGC 1512
newly born star clusters exist in both dusty and clean environments. The clean
clusters are readily seen in ultraviolet and visible light, appearing as bright, blue
clumps in the image. However, the dusty clusters are revealed only by the glow
of the gas clouds in which they are hidden, as detected in red and infrared
wavelengths by the Hubble cameras. This glow can be seen as red light
permeating the dark, dusty lanes in the ring. "The dust obscuration of clusters
appears to be an on-off phenomenon," says Maoz, who headed the collaboration.
"The clusters are either completely hidden, enshrouded in their birth clouds, or almost
completely exposed." The scientists believe that stellar winds and powerful radiation from the bright,
newly born stars have cleared away the original natal dust cloud in a fast and
efficient "cleansing" process. Aaron Barth, a co-investigator on the team, adds:
"It is remarkable how similar the properties of this starburst are to those of other
nearby starbursts that have been studied in detail with Hubble." This similarity
gives the astronomers the hope that, by understanding the processes occurring
in nearby galaxies, they can better interpret observations of very distant and faint
starburst galaxies. Such distant galaxies formed the first generations of stars,
when the universe was a fraction of its current age. Circumstellar star-forming rings are
common in the universe. Such rings within barred spiral galaxies may in fact comprise
the most numerous class of nearby starburst regions. Astronomers generally believe that
the giant bar funnels the gas to the inner ring, where stars are formed within numerous star clusters.
Studies like this one emphasize the need to observe at many different wavelengths
to get the full picture of the processes taking place.
Constellation Construction
Credit & Copyright: Jerry Lodriguss (Catching the Light)
This lovely twilight scene, recorded last April, finds a
young crescent Moon low in the west at sunset.
Above it, stars shine in the darkening sky but they
too are soon to drop below the western horizon.
These stars and constellations are prominent in the
northern hemisphere winter sky and as the season
changes, slowly give way to the stars of summer.
Sliding your mouse over the picture will detail the
constellations and stars in view, including Orion,
Gemini, Auriga, Perseus, and the Hyades and
Pleiades star clusters.
