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Post Info TOPIC: Messier 66


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RE: Messier 66
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Picture 050smPicture 050
Date 25.02.15


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PGC 34695
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Title: Stacking Analysis of 12CO and 13CO Spectra of NGC3627: Existence of non-optically thick 12CO emission?
Author: Kana Morokuma-Matsui, Kazuo Sorai, Yoshimasa Watanabe, Nario Kuno

We stacked 12CO and 13CO spectra of NGC 3627 after redefining the velocity axis of each spectrum of the mapping data so that the zero corresponds to the local mean velocity of 12CO spectra. The signal-to-noise ratios of the resulting spectra are improved by a factor of up to 3.2 compared to those obtained with normal stacking analysis. We successfully detect a weak 13CO emission from the interarm region where the emission was not detected in the individual pointings. We compare the integrated intensity ratios I12 CO/I13 CO among six characteristic regions (center, bar, bar-end, offset, arm, and interarm). We find that I12CO/I13CO in the bar and interarm are higher than those in the other regions by a factor of ~2 and I12CO/I13CO in the center is moderately high. These high I12CO/I13CO ratios in the bar and center are attributed to a high intensity ratio (T12CO/T13CO) and one in the interarm is attributed to a high ratio of the full width at half maximum of spectra (FWHM12CO/FWHM13CO). The difference between FWHM12CO and FWHM13CO of the interarm indicates the existence of two components, one with a narrow line width (~FWHM13CO) and the other with a broad line width (~FWHM12CO). Additionally, the T12CO/T13CO ratio in the broad-line-width component of the interarm is higher than the other regions. The high T12CO/T13CO in the center and bar and of the broad-line-width component in the interarm suggest the existence of non-optically thick 12CO components. We find that more than half of the 12CO emissions of the interarm are likely to be radiated from the diffuse component. Our result suggests that the use of a universal CO-to-H2 conversion factor might lead to an overestimation of molecular gas mass and underestimation of star-formation efficiency in the interarm by a factor of a few.

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NGC 3627
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NGC 3627 (also Messier 66, M66, MCG 2-29-19, Arp 16 and PGC 34695) is a magnitude +8.9 spiral galaxy located 36 million light-years away away in the constellation Leo.
M66 is part of the famous "Leo Triplet", a small group of galaxies that also includes M65 and NGC 3628. The Leo Triplet is bright enough to see with 7x50 binoculars; NGC 3628 is the fainter. The best time for observation is in winter and spring.
M 66 is located approximately between Theta and Iota Leonis, 20 arc-minutes east of M 65, a few degrees east of fairly bright 73 Leonis (5.3 mag). In amateur telescopes the galaxy is visible as a diffuse extended elliptical spot with a bright compact nucleus.
With a 250-300 mm aperture telescope the halo can be resolved into a branching spiral structure. Near the galaxy is visible a 10th magnitude foreground star.

The galaxy was discovered by French astronomer Charles Messier using a 8.38 cm (3.3 inch) refractor on the 1st March 1780.

The galaxy hosted four supernovae: SN 1973R, SN 1989b, SN 1997bs and SN 2009hd.

Right Ascension 11h 20m 15s, Declination +12 59' 24"

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RE: Messier 66
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NGC 3627: Revealing Hidden Black Holes

ngc3627_labeled_525.jpg

The spiral galaxy NGC 3627 is located about 30 million light years from Earth. This composite image includes X-ray data from NASA's Chandra X-ray Observatory (blue), infrared data from the Spitzer Space Telescope (red), and optical data from the Hubble Space Telescope and the Very Large Telescope (yellow). The inset shows the central region, which contains a bright X-ray source that is likely powered by material falling onto a supermassive black hole.
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NGC 3627
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Title: NGC 3627: a galaxy-dwarf collision?
Authors: M. Wezgowiec, M. Soida, D. J. Bomans

Group galaxies very often show distinct signs of interaction with both companion galaxies and the intragroup medium. X-ray observations are particularly helpful because they provide information on the temperatures and the densities of the hot gas in galaxies and intergalactic space. This can put important constraints on the nature and timescales of these interactions. We use the XMM-Newton X-ray observations of NGC 3627 in the Leo Triplet galaxy group to explain peculiar features visible in the polarised radio maps. We analysed soft X-ray (0.2-1 keV) emission from NGC 3627 to study the distribution of the hot gas and its temperature in different areas of the galaxy. Any change throughout the disk can reflect distortions visible in the radio polarised emission. We also studied two bright point sources that are probably tightly linked to the evolution of the galaxy. We find an increase in the temperature of the hot gas in the area of the polarised radio ridge in the western arm of the galaxy. In the eastern part of the disk we find two ultra-luminous X-ray sources. We note a large hot gas temperature difference (by a factor of 2) between the two bar ends. The polarised radio ridge in the western arm of NGC 3627 is most likely formed by ram-pressure effects caused by the movement of the galaxy through the intragroup medium. To explain the distortions visible in the eastern part of the disk in polarised radio maps, the asymmetry of the bar, and the distortion of the eastern arm, we propose a recent collision of NGC 3627 with a dwarf companion galaxy.

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Posts: 131433
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Messier 66
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Messier 66 (also known as NGC 3627) is an intermediate spiral galaxy about 36 million light-years away in the constellation Leo.
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Messier66g.jpg

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Date: 02:14 UTC, 26 March 2011



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