2020A&A...641A..97V


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.05CET01:34:46

2020A&A...641A..97V - Astronomy and Astrophysics, volume 641A, 97-97 (2020/9-1)

ALMA resolves molecular clouds in metal-poor Magellanic Bridge A.

VALDIVIA-MENA M.T., RUBIO M., BOLATTO A.D., SALDANO H.P. and VERDUGO C.

Abstract (from CDS):


Context. The Magellanic Bridge is a tidal feature located between the Magellanic Clouds, containing young stars formed in situ. Its proximity allows high-resolution studies of molecular gas, dust, and star formation in a tidal low-metallicity environment.
Aims. Our goal is to characterize gas and dust emission in Magellanic Bridge A, the source with the highest 870µm excess of emission found in single-dish surveys.
Methods. Using the ALMA telescope including the Morita Array, we mapped a 3' field of view centered on the Magellanic Bridge A molecular cloud, in 1.3mm continuum emission and 12CO(2-1) line emission at subparsec resolution. This region was also mapped in continuum at 870µm and in 12CO(2-1) line emission at ∼6pc resolution with the APEX telescope. To study its dust properties, we also use archival Herschel and Spitzer data. We combine the ALMA and APEX 12CO(2-1) line cubes to study the molecular gas emission.
Results. Magellanic Bridge A breaks up into two distinct molecular clouds in dust and 12CO(2-1) emission, which we call North and South. Dust emission in the North source, according to our best parameters from fitting the far-infrared fluxes, is ≃3K colder than in the South source in correspondence to its less developed star formation. Both dust sources present large submillimeter excesses in LABOCA data: according to our best fits the excess over the modified blackbody (MBB) fit to the Spitzer/Herschel continuum is E(870µm)∼7 and E(870µm)∼3 for the North and South sources, respectively. Nonetheless, we do not detect the corresponding 1.3mm continuum with ALMA. Our limits are compatible with the extrapolation of the MBB fits, and therefore we cannot independently confirm the excess at this longer wavelength. The 12CO(2-1) emission is concentrated in two parsec-sized clouds with virial masses of around 400 and 700M. Their bulk volume densities are n(H2)∼0.7-2.6x103cm–3, higher than typical bulk densities of Galactic molecular clouds. The 12CO luminosity to H2 mass conversion factor αCO is 6.5 and 15.3M/(K.(km/s)/pc) for the North and South clouds, calculated using their respective virial masses and 12CO(2-1) luminosities. Gas mass estimates from our MBB fits to dust emission yields masses M∼1.3x103M and 2.9x103M for North and South, respectively, a factor of ∼4 higher than the virial masses we infer from 12CO.

Abstract Copyright: © ESO 2020

Journal keyword(s): ISM: clouds - Magellanic Clouds - ISM: molecules - submillimeter: ISM

VizieR on-line data: <Available at CDS (J/A+A/641/A97): list.dat fits/*>

Status at CDS : Objects in title, abstract, text, figures, and all or part of small table(s) being processed in SIMBAD.

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9613 1
2 NAME SMC B0055-7056 Rad 00 57 15.2 -70 40 47           ~ 9 1
3 QSO B0100-760 QSO 01 02 18.6597135023 -75 46 51.733942477   18.44 17.9 17.87   ~ 36 0
4 NGC 456 HII 01 13 44.4 -73 17 26           ~ 115 0
5 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5799 1
6 NAME Magellanic Bridge HI 03 11 -77.5           ~ 345 1
7 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15069 1
8 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1761 1
9 NGC 6822 G 19 44 56.199 -14 47 51.29   18 8.1     ~ 1445 0
10 QSO B2355-534 BLL 23 57 53.2659039839 -53 11 13.691995248   18.63 17.8 16.89   ~ 133 1

    Equat.    Gal    SGal    Ecl

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2020.12.05-01:34:46

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