2004A&A...422..483A


Query : 2004A&A...422..483A

2004A&A...422..483A - Astronomy and Astrophysics, volume 422, 483-504 (2004/8-1)

Tiny-scale molecular structures in the Magellanic Clouds. I. FUSE, HST and VLT observations.

ANDRE M.K., LE PETIT F., SONNENTRUCKER P., FERLET R., ROUEFF E., CIVEIT T., DESERT J.-M., LACOUR S. and VIDAL-MADJAR A.

Abstract (from CDS):

The objective of this series of two papers is to investigate small-scale molecular structures in the Magellanic Clouds (hereafter MCs). We report on the FUSE detections of the HD and CO molecules on the lines of sight towards three Large Magellanic stars: Sk-67D05, Sk-68D135, and Sk-69D246. HD is also detected for the first time on the lines of sight towards two Small Magellanic Cloud stars: AV95 and Sk159. While the HD and CO abundances are expected to be lower in the Large Magellanic Cloud where molecular fractions are a third of the Galactic value and where the photodissociation flux is up to thousands of times as large, we report an average HD/H2 ratio of 1.4±0.5ppm and a CO/H2 ratio ranging from 0.8 to 2.7ppm similar to the Galactic values. We tentatively identify a deuterium reservoir (hereafter D-reservoir) towards the Small Magellanic Cloud, along the light path to AV95. We derive a D/H ratio ranging from 1.x10–6 to 1.1x10–5. Combining FUSE and HST/STIS data we also analyzed the H2, ClI, ClII, FeII, SII, CI, CI*, and CI** content, when available. High resolution VLT observations of NaI, CaII, and CaI were obtained in support of the lower resolution FUSE and STIS data for three targets in order to unravel the sightline velocity structures. These observations form the only such set of detections in the Magellanic Clouds to date and allow us to investigate in detail some of the physical properties of the intervening molecular gas. Our detection of the HD and CO molecules in the Magellanic Clouds is an argument for the existence of dense (nH>100cm–3) components. Furthermore, we demonstrate that these components are probably extremely small molecular clumps (possibly as small as 10–2pc) or filaments similar to the tiny-scale atomic structures (TSAS) recently observed in the halo of our Galaxy by Richter et al. (2003A&A...405.1013R). For these five sightlines, we also detected molecular hydrogen originating in the Galactic disk. From these observations we conclude that tiny-scale molecular filamentary structures are present in the disk of the Galaxy as well.

Abstract Copyright:

Journal keyword(s): ISM: molecules - galaxies: abundances

Simbad objects: 13

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Number of rows : 13
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 AzV 95 * 00 51 21.5997393360 -72 44 14.875524423 12.67 13.64 13.83   13.95 O7III((f)) 36 0
2 SK 159 s*b 01 15 58.8782438100 -73 21 24.354475568 10.80 11.77 11.90     B0Ia 69 0
3 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6021 1
4 HD 268605 s*b 04 50 18.9253786780 -67 39 38.040164010 10.244 11.2 11.377   11.322 O9.5/B0Ia 81 0
5 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15534 1
6 SN 1987A SN* 05 35 28.020 -69 16 11.07           SNIIpec 4615 2
7 HD 269896 s*b 05 37 49.1360518133 -68 55 01.642483154 11.338 9.493 11.449 11.49   ON9.7Ia+ 80 0
8 NAME 30 Dor Nebula SFR 05 38 36.0 -69 05 11           ~ 1073 2
9 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1815 1
10 HD 38282 WR* 05 38 53.3788120199 -69 02 00.896643506   10.98 11.11 11.26   WN5/6h+WN6/7h 154 1
11 LBQS 1232+0815 QSO 12 34 37.5507010309 +07 58 43.372966617     18.4     ~ 115 0
12 HD 185418 * 19 38 27.4810594267 +17 15 26.046198639 7 7.639 7.485     B0.5V 122 0
13 HD 192639 s*b 20 14 30.4275040181 +37 21 13.815126140 6.83 7.46 7.11     O7.5Iabf 274 0

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2021.09.21-12:42:08

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