2001A&A...367..299B


Query : 2001A&A...367..299B

2001A&A...367..299B - Astronomy and Astrophysics, volume 367, 299-310 (2001/2-3)

ORFEUS echelle spectra: Molecular hydrogen in disk, IVC, and HVC gas in front of the LMC.

BLUHM H., DE BOER K.S., MARGGRAF O. and RICHTER P.

Abstract (from CDS):

In front of the LMC molecular hydrogen is found in absorption near 0km/s, being local disk gas, near +60km/s in an intermediate velocity cloud, and near +120km/s, being a high velocity halo cloud. The nature of the gas is discussed based on four Orfeus far UV spectra of LMC stars and including data from the ground and from the IUE satellite. The local gas is cool and, given a span of sight lines of only 2.5°, rather fluffy. The fractional abundance of H2 varies from logf=log[N(H2)/(2.N(H2)+N(HI))]=-5.4 to -3.3. Metal depletions (up to -1.7dex for Fe) are typical for galactic disk gas. In the intermediate and high velocity gas an apparent underabundance of neutral oxygen points to an ionization level of the gas of about 90%. H2 is detected in intermediate and high velocity gas towards HD 269546. In the intermediate velocity gas we find an H2 column density of log(N)≃15.6. The H2 excitation indicates that the line of sight samples a cloud at a temperature below 150K. Column densities are too small to detect the higher UV pumped excitation levels. The high velocity H2 (log(N)≃15.6) is highly excited and probably exposed to a strong radiation field. Its excitation temperature exceeds 1000K. Due to the radial velocity difference between the halo gas and the Milky Way disk, the unattenuated disk radiation is available for H2 excitation in the halo. We do not find evidence for an intergalactic origin of this gas; a galactic as well as a Magellanic Cloud origin is possible.

Abstract Copyright:

Journal keyword(s): ISM: abundances - ISM: molecules - Galaxy: structure - ultraviolet: ISM

Simbad objects: 8

goto Full paper

goto View the references in ADS

Number of rows : 8
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     ~ 9904 1
2 PGMW 3120 * 04 56 46.812 -66 24 46.72 11.700 12.496 12.466   12.464 O5.5V((f*)) 26 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15530 1
4 HD 36402 WR* 05 26 03.9637508160 -67 29 57.087055949   11.25 11.621 11.65   (WC) 134 0
5 HD 269546 WR* 05 26 45.3199315750 -68 49 52.786974246 9.00 9.83 9.86 9.76 9.76 WN5b(h)+B3I 103 0
6 HD 269698 s*b 05 31 44.2083142709 -67 38 01.378514813 9.520 12.00 12.22 12.47 11.167 O4Ia 109 0
7 2E 1919 Sy1 08 10 58.6637281539 +76 02 42.449416413   15.03 14.71     ~ 428 0
8 HD 93521 * 10 48 23.5116139485 +37 34 13.089937784 5.67 6.79 7.03     O9.5IIInn 409 1

To bookmark this query, right click on this link: simbad:objects in 2001A&A...367..299B and select 'bookmark this link' or equivalent in the popup menu


2021.09.20-10:17:45

© Université de Strasbourg/CNRS

    • Contact