Image Gallery - Striking Galaxy Images
Heart of the Milky Way - Composite
right|78772da1a3b4b4ac49d06dc9a6d06d2fec0d535f|Milky Way center in 3 Wave Bands|]This first image is of the central region of the Milky Way galaxy and is a composite of three separate images of the same region, each taken in a different wave band. This is the heart of our own megalopolis of stars.
Distance to the center: ~25,000 light years. (And we are in the Milky Way galaxy.)
Mass of the entire Milky Way: estimates range from about 200 billion to 1.9 trillion solar masses. Karachentsev’s “Catalog of nearby galaxies” gives 141 billion solar masses.
Diameter of the entire Milky Way: 100,000 light years.
An image from the Spitzer Space Telescope in infrared (IR) was combined with another from the Hubble in near-infrared, and a third image from the Chandra X-ray Observatory.
The image at right shows the three separate images.
Top: reddish clouds from Spitzer (IR).
Middle: golden streaks from Hubble (near-IR).
Bottom: blue and violet clouds from Chandra (X-ray).
References:
Christian, Eric and Safi-Harb, Samar, “Size of the Milky Way ,” https://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980317b.html
Eisenhauer, F., et al, SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month, https://adsabs.harvard.edu/abs/2005ApJ…628..246E
Evans, N. and Wilkinson, M., “The Mass of the Andromeda galaxy,” https://adsabs.harvard.edu/abs/2000MNRAS.316..929E
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
NASA, https://www.nasa.gov/mission_pages/spitzer/news/spitzer-20091110.html
Large Magellanic Cloud - Stellar Nursery
A close-up of the Large Magellanic Cloud (LMC) showing a stellar nursery—birthplace of stars. The LMC is one of the satellite galaxies of the Milky Way, visible only from the Southern Hemisphere or from near the equator. This is the largest satellite of our galaxy.
Distance: 157,000 light years.
Mass: Estimates vary greatly and include 8.7 billion solar masses (van der Marel) and 3.3 billion solar masses (Karachentsev).
Diameter: 14,000 light years.
References:
Hodge, Paul, “Magellanic Cloud,” https://www.britannica.com/EBchecked/topic/356551/Magellanic-Cloud
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Macri, L., “A New Cepheid Distance to the Maser-Host Galaxy NGC 4258 and Its Implications for the Hubble Constant,” https://adsabs.harvard.edu/abs/2006ApJ…652.1133M
Van der Marel, Roeland, “The Large Magellanic Cloud: Structure and Kinematics,” https://ned.ipac.caltech.edu/level5/March04/Marel/Marel5_2.html
Small Magellanic Cloud - Stellar Nursery
Near the LMC resides the Small Magellanic Cloud (SMC). This view includes its own stellar nursery. The SMC also orbits the Milky Way galaxy. The irregular shape of this galaxy is thought to have been caused by tidal interaction with both the LMC and the Milky Way. Three astrophysicists (Mathewson, Ford and Visvanathan) have proposed that there is a third Magellanic cloud behind the SMC, which they call the Mini-Magellanic Cloud (MMC), because they estimate that the SMC had been split in two many millions of years ago by the tidal forces from its larger neighbors.
Distance: 198,000 light years.
Mass: 1.58 billion solar masses (Karachentsev). Dark matter estimated at 6.5 billion solar masses (Bekki).
Diameter: 7,000 light years.
References:
Bekki, Kenji and Stanimirovic, Snezana, “The total mass and dark halo properties of the Small Magellanic Cloud,” https://adsabs.harvard.edu/abs/2009MNRAS.395..342B
Hilditch, R., et al, “Forty eclipsing binaries in the Small Magellanic Cloud: fundamental parameters and Cloud distance,” https://adsabs.harvard.edu/abs/2005MNRAS.357..304H
Hodge, Paul, “Magellanic Cloud,” https://www.britannica.com/EBchecked/topic/356551/Magellanic-Cloud
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Mathewson, D., et al, “The Structure of the Small Magellanic Cloud,” https://adsabs.harvard.edu/full/1986ApJ…301..664M
Stars Like Dust - Andromeda Galaxy Closeup
This extreme closeup, taken by the Hubble Space Telescope, shows the grainy texture of our closest large spiral galaxy, also known as the “Andromeda” galaxy because of its location in that northerly constellation. It is one of the few galaxies visible to the unaided eye. This is one of our next-door neighbors and contains about a trillion stars.
Andromeda, the Milky Way and Triangulum galaxies make up the three largest members of the Local Group of galaxies.
Distance: 2.51 million light years (Karachentsev).
Mass: Estimates vary greatly and include 1.23 thousand billion solar masses (Evans) and 269 billion solar masses (Karachentsev).
Diameter: 117,000 light years (Karachentsev).
References:
Evans, N. and Wilkinson, M., “The Mass of the Andromeda galaxy,” https://adsabs.harvard.edu/abs/2000MNRAS.316..929E
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Young, Kelly, “Andromeda galaxy hosts a trillion stars,” https://www.newscientist.com/article/dn9282-andromeda-galaxy-hosts-a-trillion-stars.html
The Heart of Centaurus A
A close-up of the heart of Centaurus A, a relatively bright, nearby galaxy, roughly 12 million light years away. Yes, it takes between 10 and 16 million years for the light to travel from there to here. And that’s relatively close-by on the cosmic scale. Scientists note that Centaurus A is undergoing an unusual burst of star formation. And, as scientists have suspected from this burst, data from the Spitzer space telescope helps to confirm that this galaxy is undergoing a collision by gobbling up a spiral galaxy.
At the core of this galaxy resides a black hole estimated to be a billion times as massive as our own Sun.
Distance: 11.9 million light years (Karachentsev).
Mass: 537 billion solar masses (Karachentsev).
Diameter: 94,000 light years (Karachentsev).
References:
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
NGC 5128, https://www.sidleach.com/ngc5128.htm
Beautiful Spiral of M51
A close-up of face-on, spiral galaxy, M51, also known as the Whirlpool galaxy (NGC 5194). This galaxy has a very large companion galaxy (see the next slide).
Distance: 26.1 million light years (Karachentsev).
Mass: 35.48 billion solar masses (Karachentsev).
Diameter: 79,700 light years (Karachentsev).
Reference:
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Whirlpool Galaxy and Pup
The beautiful Whirlpool galaxy (M51, NGC 5194) and its companion galaxy (NGC 5195). This is perhaps the most famous of the interacting galaxies. Because of the tidal bridge from the larger, Whirlpool galaxy is overlaying the hub of the smaller companion, it seems certain that the “pup” is behind the Whirlpool.
Distance: 26.1 million light years (Karachentsev).
NGC 5194 (Whirlpool, M51a)
Mass: 35.48 billion solar masses (Karachentsev).
Diameter: 79,700 light years (Karachentsev).
NGC 5195 (“pup,” M51b)
Mass: unknown.
Diameter: 38,600 light years (Karachentsev).
Reference:
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Magestic Sombrero Galaxy
Bold and simple, the “Sombrero” galaxy (M104, NGC 4594) displaying its distinctive dust lane. Because of the rapid movement of stars near the core, scientists feel that a black hole as massive as a billion suns resides at the center (Kormendy).
Distance: 30.4 million light years (Karachentsev).
Mass: 417 billion solar masses (Karachentsev).
Diameter: 68,800 light years (Karachentsev).
References:
Karachentsev, I., et al, “Catalog of neighboring galaxies,” https://vizier.cfa.harvard.edu/viz-bin/Cat?J/AJ/127/2031
Kormendy, J, et al, “Hubble Space Telescope Spectroscopic Evidence for a 1 X 10 9 Msun Black Hole in NGC 4594,” https://adsabs.harvard.edu/abs/1996ApJ…473L..91K
A Rose of Distant Galaxies
Arp 273 consists of two interacting galaxies, UGC 1810 and nearly edge-on UGC 1813, plus a tenuous tidal bridge connecting them. This image is a composite of three pictures in three different wave bands—red, blue and ultraviolet.
Distance: ~300 million light years.
Mass: unknown, but larger is estimated to be 5 times the mass of the smaller.
Diameter: unknown
Reference:
Hubble Site, https://www.hubblesite.org/newscenter/archive/releases/galaxy/2011/11/full/
NGC 4911 in the Coma Cluster of Galaxies
NGC 4911 in the Coma Cluster of galaxies. Notice all of the other galaxies nearby and in the background. It seems rare that a spiral galaxy would stand so close to the heart of a galactic cluster.
Distance: 320 million light years.
Mass: unknown.
Diameter: unknown.
Reference:
Townsend, Jason, ed., “‘Island Universe’ in the Coma Cluster,” https://www.nasa.gov/multimedia/imagegallery/image_feature_1739.html
“The Mice” Playing Intergalactic Tag
This is one of my favorites—NGC 4676, also known as “The Mice.” As much as 170 hundred million years ago, these two galaxies collided and are now paying the consequences by the stars being spilled across inter-galactic space. Another effect of this collision is the formation of many new star clusters.
Distance: 290 million light years.
Mass: unknown.
Diameter: not an easy thing to define with both galaxies so distorted.
Reference:
Chien, L., et al, “Multiobject Spectroscopy of Young Star Clusters in NGC 4676,” https://adsabs.harvard.edu/abs/2007ApJ…660L.105C
Galaxies at the Edge of Forever
This is the Hubble Ultra-Deep Field, a picture which took nearly four months for the Hubble telescope to take. This picture was taken in a relatively dark patch of sky, away from bright stars and supposedly devoid of anything to see. Nearly every object in this field of view is a galaxy and there are roughly 10,000 of them. The patch of sky is tiny—about 1/70 of the solid angle taken up by our Moon. And yet it remains full of galaxies at the “edge” of space and time. The galaxies in this image are estimated to be between 400 and 800 million years younger than the Big Bang itself.
Distance: about 13 billion light years (13,000 million).
Reference:
-- , “Hubble’s Deepest View Ever of the Universe Unveils Earliest Galaxies,” https://hubblesite.org/newscenter/archive/releases/2004/07/
