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Post Info TOPIC: M104
Blobrana


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Messier 104
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Title: The Distance to M104
Author: Kristen B. W. McQuinn, Evan D. Skillman, Andrew E. Dolphin, Danielle Berg, Robert Kennicutt

M104 (NGC 4594; the Sombrero galaxy) is a nearby, well-studied elliptical galaxy included in scores of surveys focused on understanding the details of galaxy evolution. Despite the importance of observations of M104, a consensus distance has not yet been established. Here, we use newly obtained Hubble Space Telescope optical imaging to measure the distance to M104 based on the tip of the red giant branch method. Our measurement yields the distance to M104 to be 9.55 +/- 0.13 +/- 0.31 Mpc equivalent to a distance modulus of 29.90 +/- 0.03 +/- 0.07 mag. Our distance is an improvement over previous results as we use a well-calibrated, stable distance indicator, precision photometry in a optimally selected field of view, and a Bayesian Maximum Likelihood technique that reduces measurement uncertainties. The most discrepant previous results are due to Tully-Fisher method distances, which are likely inappropriate for M104 given its peculiar morphology and structure. Our results are part of a larger program to measure accurate distances to a sample of well-known spiral galaxies (including M51, M74, and M63) using the tip of the red giant branch method.

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Blobrana


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Posts: 131433
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NGC 4594
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NGC 4594 (also M104, Messier 104, Sombrero Galaxy and PGC 42407) is a magnitude +9.0 unbarred spiral galaxy located 29.3 ±1.6 million light-years away in the constellation Virgo. 

The galaxy was discovered by German astronomer Pierre Méchain using a 3.5" refractor on the 11th May 1781.

Right Ascension 12h 39m 59.4s, Declination -11° 37' 23"

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Blobrana


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RE: M104
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Sombrero Galaxy - 4/17/10

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Sombrero Galaxy in 60 Seconds

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Blobrana


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Posts: 131433
Date:
Sombrero galaxy
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  NASA's Spitzer Finds Galaxy with Split Personality

While some galaxies are rotund and others are slender disks like our spiral Milky Way, new observations from NASA's Spitzer Space Telescope show that the Sombrero galaxy is both. The galaxy, which is a round, elliptical with a thin disk embedded inside, is one of the first known to exhibit characteristics of the two different types. The findings will lead to a better understanding of galaxy evolution, a topic still poorly understood.
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Blobrana


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SUCD1
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The biggest dwarf for miles around has been discovered in the night sky. The so-called 'dwarf galaxy' is only the size of a star cluster but may contain 10 times as many stars as a cluster, making it particularly bright.
The discovery, made by a team of five Australian and three North American astronomers, was published in the March Monthly Notices of the Royal Astronomical Society.
It is the closest ultra-compact dwarf galaxy to Earth. It is far brighter and more massive than the clusters of stars that usually surround galaxies, and was born in the very early stages of the formation of the universe.

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Blobrana


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Title: An Ultra Compact Dwarf around the Sombrero galaxy (M104): the Nearest Massive UCD
Authors: George K. T. Hau, Lee R. Spitler, Duncan A. Forbes, Robert N. Proctor, Jay Strader, J. Trevor Mendel, Jean P. Brodie, William E. Harris

We report the discovery of an Ultra Compact Dwarf (UCD) associated with the Sombrero galaxy (M104). This is the closest massive UCD known and the first spectroscopically verified massive UCD which is located in a low density environment.
The object, we name SUCD1, was identified in HST/ACS imaging and confirmed to be associated with the Sombrero galaxy by its recession velocity obtained from Keck spectra. The light profile is well fitted by a Wilson model. We measure a half light size of 14.7 ±1.4 pc, an absolute magnitude of M_V = -12.3 mag (M_K = -15.1 mag) and an internal velocity dispersion of 25.0 ±5.6 km/s. Such values are typical of UCDs. From Lick spectral indices we measure a luminosity-weighted central age of 12.6 ±0.9 Gyrs, [Fe/H] of -0.08 ±0.08 dex and [alpha/Fe] of 0.06 ±0.07 dex. The lack of colour gradients suggests these values are representative of the entire UCD. The derived stellar and virial masses are the same, within errors, at ~3.3 x 10E7 Msun. Thus we find no strong evidence for dark matter or the need to invoke a non-standard IMF.
We also report arguably the first X-ray detection of a bona fide UCD, which we attribute to the presence of Low-Mass X-ray Binaries (LMXBs). The X-ray luminosity of L_X = 0.56 x 10E38 erg/s is consistent with the values observed for GCs of the same metallicity. Overall we find SUCD1 has properties similar to other known UCDs and massive GCs.

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Blobrana


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Sombrero Galaxy
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The Sombrero, also known as M104, is one of the largest galaxies in the nearby Virgo cluster, about 28 million light years from Earth. This Great Observatories view of the famous Sombrero galaxy was made using NASA's Chandra X-ray Observatory, Hubble Space Telescope and Spitzer Space Telescope. The main figure shows the combined image from the three telescopes, while the three inset images show the separate observatory views.
The Chandra X-ray image (in blue) shows hot gas in the galaxy and point sources that are a mixture of objects within the Sombrero as well as quasars in the background. The Chandra observations show that diffuse X-ray emission extends over 60,000 light years from the centre of the Sombrero. (The galaxy itself spans 50,000 light years across.) Scientists think this extended X-ray glow may be the result of a wind from the galaxy, primarily being driven by supernovas that have exploded within its bulge and disk. The Hubble optical image (green) shows a bulge of starlight partially blocked by a rim of dust, as this spiral galaxy is being observed edge on. That same rim of dust appears bright in Spitzer's infrared image, which also reveals that Sombrero's central bulge of stars.

sombrero
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Credit: X-ray: NASA/UMass/Q.D.Wang et al.; Optical: NASA/STScI/AURA/Hubble Heritage; Infrared: NASA/JPL-Caltech/Univ. AZ/R.Kennicutt/SINGS Team

Position (J2000): RA 12h 39m 59.4s | Dec -11º 37' 23

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Blobrana


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Posts: 131433
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M104
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This floating ring is the size of a galaxy. In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies.


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The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The above image shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-colour on an existing image taken by the Hubble Space Telescope in optical light.
The Sombrero Galaxy, also known as Messier 104, spans about 50,000 light years across and lies 28 million light years away. M104 can be seen with a small telescope in the direction of the constellation of Virgo.

The Spitzer space telescope picture is composed of four images taken at 3.6 (blue), 4.5 (green), 5.8 (orange), and 8.0 (red) microns. The contribution from starlight (measured at 3.6 microns) has been subtracted from the 5.8 and 8-micron images to enhance the visibility of the dust features.
Position (J2000): RA: 12h39m59.4s Dec: -11d37m23s


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-- Edited by Blobrana at 09:55, 2005-05-11

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