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Post Info TOPIC: Messier33
Blobrana


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Posts: 131433
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RE: Messier33
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Title: Chandra ACIS Survey of M33 (ChASeM33): A First Look
Authors: Paul P. Plucinsky, Benjamin Williams, Knox S. Long, Terrance J. Gaetz, Manami Sasaki, Wolfgang Pietsch, Ralph Tuellmann, Randall K. Smith, William P. Blair, David Helfand, John P. Hughes, P. Frank Winkler, Miguel de Avillez, Luciana Bianchi, Dieter Breitschwerdt, Richard J. Edgar, Parviz Ghavamian, Jonathan Grindlay, Frank Haberl, Robert Kirshner, Kip Kuntz, Tsevi Mazeh, Thomas G. Pannuti, Avi Shporer, David A. Thilker

We present an overview of the Chandra ACIS Survey of M33 (ChASeM33): A Deep Survey of the Nearest Face-on Spiral Galaxy. The 1.4 Ms survey covers the galaxy out to R ~ 18\arcmin (~ 4 kpc). These data provide the most intensive, high spatial resolution assessment of the X-ray source populations available for the confused inner regions of M33. Mosaic images of the ChASeM33 observations show several hundred individual X-ray sources as well as soft diffuse emission from the hot interstellar medium. Bright, extended emission surrounds the nucleus and is also seen from the giant \hii regions NGC 604 and IC 131. Fainter extended emission and numerous individual sources appear to trace the inner spiral structure. The initial source catalogue, arising from ~2/3 of the expected survey data, includes 394 sources significant at the 3\sigma confidence level or greater, down to a limiting luminosity (absorbed) of ~1.6\ergs{35} (0.35 -- 8.0 keV). The hardness ratios of the sources separate those with soft, thermal spectra such as supernova remnants from those with hard, non-thermal spectra such as X-ray binaries and background active galactic nuclei. Emission extended beyond the Chandra point spread function is evident in 23 of the 394 sources. Cross-correlation of the ChASeM33 sources against previous catalogues of X-ray sources in M33 results in matches for the vast majority of the brighter sources and shows 28 ChASeM33 sources within 10\arcsec of supernova remnants identified by prior optical and radio searches. This brings the total number of such associations to 31 out of 100 known supernova remnants in M33.

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Blobrana


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Posts: 131433
Date:
M33SNR21
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Title: Chandra ACIS Survey of M33 (ChASeM33): X-ray Imaging Spectroscopy of M33SNR21, the Brightest X-ray Supernova Remnant in M33
Authors: Terrance J. Gaetz, William P. Blair, John P. Hughes, P. Frank Winkler, Knox S. Long, Thomas G. Pannuti, Benjamin Williams, Richard J. Edgar, Parviz Ghavamian, Paul P. Plucinsky, Manami Sasaki, Robert P. Kirshner, Miguel Avillez, Dieter Breitschwerdt

We present and interpret new X-ray data for M33SNR21, the brightest X-ray supernova remnant (SNR) in M33. The SNR is in seen projection against (and appears to be interacting with) the bright HII region NGC592. Data for this source were obtained as part of the Chandra ACIS Survey of M33 (ChASeM33) Very Large Project. The nearly on-axis Chandra data resolve the SNR into a ~5" diameter (20 pc at our assumed M33 distance of 817 ±58 kpc) slightly elliptical shell. The shell is brighter in the east, which suggests that it is encountering higher density material in that direction. The optical emission is coextensive with the X-ray shell in the north, but extends well beyond the X-ray rim in the southwest. Modelling the X-ray spectrum with an absorbed sedov model yields a shock temperature of 0.46(+0.01,-0.02) keV, an ionisation timescale of n_e t = 2.1 (+0.2,-0.3) x 10^{12} cm^{-3} s, and half-solar abundances (0.45 (+0.12, -0.09)). Assuming Sedov dynamics gives an average preshock H density of 1.7 ± 0.3 cm^{-3}. The dynamical age estimate is 6500 ± 600 yr, while the best fit n_e t value and derived n_e gives 8200 ± 1700 yr; the weighted mean of the age estimates is 7600 ± 600 yr. We estimate an X-ray luminosity (0.25-4.5 keV) of (1.2 ± 0.2) x 10^{37} ergs s^{-1} (absorbed), and (1.7 ± 0.3) x 10^{37} ergs s^{-1} (unabsorbed), in good agreement with the recent XMM-Newton determination. No significant excess hard emission was detected; the luminosity \le 1.2 x 10^{35} ergs s^{-1} (2-8 keV) for any hard point source.

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Blobrana


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Posts: 131433
Date:
RE: Messier33
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Title: Keck spectroscopy and Spitzer Space Telescope analysis of the outer disk of the Triangulum Spiral Galaxy M33
Authors: David L. Block (1,4), Francoise Combes (2), Ivanio Puerari (3), Kenneth C. Freeman (4), Alan Stockton (5), Gabriela Canalizo (6), Thomas H. Jarrett (7), Robert Groess (1), Guy Worthey (8), Robert D. Gehrz (9), Charles E. Woodward (9), Elisha F. Polomski (9), Giovanni G. Fazio (10)-- ((1) WITS, South Africa, (2) LERMA, Paris, (3) INAOE, Mexico, (4) Mount Stromlo, Australia, (5) IfA, Hawaii, (6) IGPP, California, (7) CALTECH, (8) WSU, Washington, (9) Univ. Minnesota, (10) CfA, Harvard)

In an earlier study of the spiral galaxy M33, we photometrically identified arcs or outer spiral arms of intermediate age (0.6 Gyr - 2 Gyr) carbon stars precisely at the commencement of the HI-warp. Stars in the arcs were unresolved, but were likely thermally-pulsing asymptotic giant branch carbon stars. Here we present Keck I spectroscopy of seven intrinsically bright and red target stars in the outer, northern arc in M33. The target stars have estimated visual magnitudes as faint as V \sim 25 mag. Absorption bands of CN are seen in all seven spectra reported here, confirming their carbon star status. In addition, we present Keck II spectra of a small area 0.5 degree away from the centre of M33; the target stars there are also identified as carbon stars. We also study the non-stellar PAH dust morphology of M33 secured using IRAC on board the Spitzer Space Telescope. The Spitzer 8 micron image attests to a change of spiral phase at the start of the HI warp. The Keck spectra confirm that carbon stars may safely be identified on the basis of their red J-K_s colours in the outer, low metallicity disk of M33. We propose that the enhanced number of carbon stars in the outer arms are an indicator of recent star formation, fuelled by gas accretion from the HI-warp reservoir.

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Blobrana


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Posts: 131433
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Star Cluster Candidates in M33
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Title: A Catalogue of Star Cluster Candidates in M33
Authors: Ata Sarajedini, Conor L. Mancone

We present a new catalogue of star cluster candidates in the nearby spiral galaxy M33. It is based on eight existing catalogues wherein we have cross-referenced identifications and endeavoured to resolve inconsistencies between them. Our catalogue contains 451 candidates of which 255 are confirmed clusters based on HST and high resolution ground-based imaging. The catalogue contains precise cluster positions (RA and Dec), magnitudes and colours in the UBVRIJHKs filters, metallicities, radial velocities, masses and ages, where available, and galactocentric distances for each cluster. The colour distribution of the M33 clusters appears to be similar to those in the Large Magellanic Cloud with major peaks at (B-V)o~0.15, and (B-V)o~0.65. The intrinsic colours are correlated with cluster ages, which range from 10^{7.5} to 10^{10.3} years. The age distribution of the star clusters supports the notion of rapid cluster disruption with a slope of alpha=-1.09 +/- 0.07 in the dN_{cluster}/dt ~ t^{alpha} relation. In addition, comparison to theoretical single stellar population models suggests the presence of an age-metallicity relation among these clusters with younger clusters being more metal-rich. Analysis of the radial distribution of the clusters yields some evidence that younger clusters (age <~ 1 Gyr) may be more concentrated toward the centre of M33 than older ones. A similar comparison with the radial profile of the M33 field stars shows the clusters to be more centrally concentrated at the greater than 99.9% confidence level. Possible reasons for this are presented and discussed; however, the overwhelming conclusion seems to be that a more complete and thorough cluster search is needed covering at least 4 square degrees centred on M33.

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Blobrana


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Posts: 131433
Date:
RE: Messier33
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Title: The Structure and Content of Galaxy Outskirts
Authors: Annette Ferguson (IfA, Edinburgh)
(revised v2)

The outer regions of galaxies are expected to contain important clues about the way in which galaxies are assembled. Although quantitative study of these parts has been severely limited in the past, breakthroughs are now being made thanks to the combination of wide-area star counts, deep HST imagery and 8-m class spectroscopy. I review here several recent results concerning substructure, star clusters and stellar halos in the outer regions of our nearest large neighbours, M31 and M33.

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Blobrana


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Posts: 131433
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Next week much of the world will mark the passing of yet another year, but according to scientists the earth and universe are a few billion years older than anybody realised.
While people have been sleeping, fighting, eating and worrying this year, the universe became much bigger, with astronomers in the United States recalculating cosmic light to better measure intergalactic distances.
Dr Fred Watson from the Anglo-Australian Observatory at Coonabarabran says the distance of a relatively nearby galaxy was used as a new standard.

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Blobrana


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Posts: 131433
Date:
Nova M33 2006
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Nova M33 2006 (Dans M33) : découverte le 28 septembre 2006 par l'Université du Texas; Koichi Itagaki. Magnitude : 16,5. Magnitude relevée : 17,475. Mon image (Cliquez sur lien)

Position(2000): R.A. = 01h33m18s.66, Dec. = +33°49'49".2
The nova is located 6' 56".0 west and 10' 13."4 north of the centre of the spiral galaxy (M33. NGC598)

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Blobrana


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Posts: 131433
Date:
M33 Distance Determination
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Title: The First DIRECT Distance Determination to a Detached Eclipsing Binary in M33
Authors: A. Z. Bonanos, K. Z. Stanek, R. P. Kudritzki, L.M. Macri, D. D. Sasselov, J. Kaluzny, P. B. Stetson, D. Bersier, F. Bresolin, T. Matheson, B.J. Mochejska, N. Przybilla, A.H. Szentgyorgyi, J. Tonry, G. Torres

Researchers present the first direct, i.e. not involving intermediate steps, distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project.
Located in the OB 66 association at coordinates (alpha, delta)=(01:33:46.17,+30:44:39.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. They obtained follow-up BV time series photometry, JHKs photometry and optical spectroscopy from which they determined the parameters of the system. It contains two O7 main sequence stars with masses of 33.4 ±3.5 Mo and 30.0 ±3.3 Mo and radii of 12.3 ±0.4 Ro and 8.8 ±0.3 Ro, respectively. The researchers derive temperatures of 37000 ±1500 K and 35600 ±1500 K. Using BVRJHKs photometry for the flux calibration, they obtain a distance modulus of 24.92 ±0.12 mag (964 ±54 kpc), which is ~0.3 mag longer than the Key Project distance to M33.
They discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder.

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Blobrana


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Posts: 131433
Date:
Triangulum galaxy
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The Milky Way galaxy has two sister spirals competing for attention from photographers. The Andromeda galaxy usually wins the contest, posing frequently for cosmic portraits. In this new image from the MMT Observatory's 6.5-meter telescope, the second sister finally gets her due notice. Here, the Triangulum galaxy emerges from the shadows to reveal stunning swirls of stars and dust dotted with brilliant pink nebulae.

m33
(Negative image)
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Credit: N. Caldwell, B. McLeod, and A. Szentgyorgyi (SAO)

The new photograph of the Triangulum galaxy showcases the dazzling capabilities of MMT's new Megacam instrument. Megacam was developed at the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Mass., under the direction of astronomer Brian McLeod. This state-of-the-art camera consists of 36 CCD chips, each of which contains 9 million picture elements (pixels), making Megacam one of the largest digital cameras in the world

"Megacam is like a turbocharged household digital camera. While a typical digital camera might have eight or nine megapixels, Megacam has 340 megapixels" - Nelson Caldwell, SAO astronomer.

Caldwell and McLeod picked the Triangulum galaxy to be one of the first objects photographed by Megacam. This galaxy, also known as Messier 33 or M33 for its designation in the catalogue compiled by Charles Messier, lies about 2.4 million light-years from Earth. It spans about twice the diameter of the full moon in the night sky. Although large, its light is diffuse, making it a challenging object to spot with the unaided eye. The view of M33 is best in binoculars or small telescopes at low magnification.
Newly formed blue stars and dark dusty patches outline the spiral arms of M33. Pink filaments of hydrogen gas mark regions of active star formation similar to the Milky Way's Orion Nebula. The eye-catching nebula at upper left in this image, designated NGC 604, stretches across an impressive 1,500 light-years and holds more than 200 hot, young stars that light it from within.

The Triangulum galaxy is the smallest of the three spirals in the local neighbourhood, holding as much mass as 10-40 billion suns. In comparison, the Milky Way holds about 200 billion suns' worth of normal matter, while Andromeda is even heftier.

"Triangulum is not a colossal giant like the Milky Way or Andromeda. But it has a charm and beauty of its own that belies its junior citizen status" - Nelson Caldwell.

The MMT telescope contains a primary mirror 6.5 meters in diameter, making it among the largest optical telescopes in the world. Astronomers use the MMT for various projects such as searching for extrasolar planets, making 3-d maps of galaxies in space, and finding quasars that existed when the universe was only one-tenth of its present age. SAO operates the MMT Observatory, located south of Tucson, Arizonia, in partnership with the University of Arizona.

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Blobrana


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Posts: 131433
Date:
Messier33
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Expand (549kb, 2834 x 3450)
Position(2000): RA = 01 : 33.9 Dec = +30 : 39
This X-ray image, showing a mosaic of the spiral galaxy M33, was taken by the X-ray imaging cameras on board ESA's XMM-Newton in August 2000. The marked ellipse limits the area of the optical view of this galaxy. Thanks to XMM-Newton data and images like these, scientists around the world have produced 1000 papers so far, a major achievement for the mission.
Credits: W. Pietsch, MPE (Garching, Germany)/ESA


The spiral galaxy Messier33 lies at a distance of 3.0 million light-years away in the constellation Triangulum, and is part of the Local Group of galaxies. LGS 3, is possibly a satellite of M33.
The distance of M33 from M31 is about 750,000 light-years.
M33 is approaching our Galaxy at 24 km/sec.

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