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FUSE observations of molecular hydrogen on the line of sight towards HD141569A

By SpaceRef Editor
August 16, 2005
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Astrophysics, abstract

From: Claire Martin-Za\"idi [view email]
Date: Mon, 13 Jun 2005 15:34:39 GMT (367kb)

FUSE observations of molecular hydrogen on the line of sight towards

C. Martin-Zaidi (1),
M. Deleuil (1),
T. Simon (2),
J.-C. Bouret (1),
A. Roberge (3),
P.D. Feldman (4),
A. Lecavelier des Etangs (5),
A. Vidal-Madjar (5) ((1)Laboratoire d’Astrophysique de Marseille, CNRS-Université de Provence, France, (2)Institute for Astronomy, University of Hawaii, USA, (3)Carnegie Institution of Washington, USA, (4)Department of Physics and Astronomy, JHU, Baltimore, USA, (5)Institut d’Astrophysique de Paris, France)

Comments: accepted for publication in A&A

We present an analysis of the Far Ultraviolet Spectroscopic Explorer (FUSE)
spectrum of HD141569A, a transitional object known to possess a circumstellar
disk. We observe two components of gas at widely different temperatures along
the line of sight. We detect cold H2, which is thermalized up to J=2 at a
kinetic temperature of 51K. Such low temperatures are typical of the diffuse
interstellar medium. Since the line of sight to HD141569A does not pass through
its disk, it appears that we are observing the cold H2 in a low extinction
envelope associated with the high Galactic latitude dark cloud complex L134N,
which is in the same direction and at nearly the same distance as HD141569A.
The column densities of the higher J-levels of H2 suggest the presence of warm
gas along the line of sight. The excitation conditions do not seem to be
consistent with what is generally observed in diffuse interstellar clouds. The
observed radial velocity of the gas implies that the UV spectral lines we
observe are likely interstellar in origin rather than circumstellar, although
our absorption line study does not definitely rule out the possibility that the
warm gas is close to the star. The discovery of such warm gas along the line of
sight may provide evidence for turbulent phenomena in the dark cloud L134N.

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