2018A&A...612A..51B


Query : 2018A&A...612A..51B

2018A&A...612A..51B - Astronomy and Astrophysics, volume 612A, 51-51 (2018/4-1)

Properties and rotation of molecular clouds in M 33.

BRAINE J., ROSOLOWSKY E., GRATIER P., CORBELLI E. and SCHUSTER K.-F.

Abstract (from CDS):

The sample of 566 molecular clouds identified in the CO(2-1) IRAM survey covering the disk of M 33 is explored in detail. The clouds were found using CPROPS and were subsequently catalogued in terms of their star-forming properties as non-star-forming (A), with embedded star formation (B), or with exposed star formation (C, e.g., presence of Hα emission). We find that the size-linewidth relation among the M 33 clouds is quite weak but, when comparing with clouds in other nearby galaxies, the linewidth scales with average metallicity. The linewidth and particularly the line brightness decrease with galactocentric distance. The large number of clouds makes it possible to calculate well-sampled cloud mass spectra and mass spectra of subsamples. As noted earlier, but considerably better defined here, the mass spectrum steepens (i.e., higher fraction of small clouds) with galactocentric distance. A new finding is that the mass spectrum of A clouds is much steeper than that of the star-forming clouds. Further dividing the sample, this difference is strong at both large and small galactocentric distances and the A vs. C difference is a stronger effect than the inner vs. outer disk difference in mass spectra. Velocity gradients are identified in the clouds using standard techniques. The gradients are weak and are dominated by prograde rotation; the effect is stronger for the high signal-to-noise clouds. A discussion of the uncertainties is presented. The angular momenta are low but compatible with at least some simulations. Finally, the cloud velocity gradients are compared with the gradient of disk rotation. The cloud and galactic gradients are similar; the cloud rotation periods are much longer than cloud lifetimes and comparable to the galactic rotation period. The rotational kinetic energy is 1-2% of the gravitational potential energy and the cloud edge velocity is well below the escape velocity, such that cloud-scale rotation probably has little influence on the evolution of molecular clouds.

Abstract Copyright: © ESO 2018

Journal keyword(s): galaxies: individual: M 33 - Local Group - galaxies: ISM - ISM: clouds - ISM: molecules - stars: formation

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12029 1
2 [GBR2012] 4 MoC 01 33 36.46 +30 20 07.8           ~ 3 0
3 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 5574 1
4 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 1009 3
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16411 1
6 M 81 Sy2 09 55 33.1726556496 +69 03 55.062505368   7.89 6.94     ~ 4243 3
7 M 51 GiP 13 29 52.698 +47 11 42.93   9.26 8.36 8.40   ~ 4140 4
8 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13329 0
9 AGAL G030.818-00.056 cor 18 47 47.0 -01 54 28           ~ 144 0
10 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1506 0
11 NAME Local Group GrG ~ ~           ~ 7843 0

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2022.12.07-05:28:29

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