Results 11 to 20 of about 3,169 (205)
A Dynamical Study of the Circumstellar Gas in UX Orionis [PDF]
Astronomy & Astrophysics, 2002 We present the results of a high spectral resolution study of the circumstellar (CS) gas around the intermediate mass, pre-main sequence star UX Ori. The results are based on a set of 10 echelle spectra, monitoring the star on time scales of months, days and hours.
Mora, A. +24 more
core +8 more sources
Exocomets in the circumstellar gas disk of HD 172555 [PDF]
Astronomy & Astrophysics, 2014 The source HD172555 is a young A7V star surrounded by a debris disk with a gaseous component. Here, we present the detection of variable absorption features detected simultaneously in the Ca II K and H doublet lines (at 3,933 and 3,968 Angstrom). We identified the presence of these absorption signatures at four different epochs in the 129 HARPS high ...
Kiefer, F. +5 more
openaire +5 more sources
Modeling Circumstellar Gas Emission around a White Dwarf Using cloudy
The Astronomical JournalThe chemical composition of an extrasolar planet is fundamental to its formation, evolution, and habitability. In this study, we explore a new way to measure the chemical composition of the building blocks of extrasolar planets by measuring the gas ...
Siyi Xu +11 more
doaj +2 more sources
On the gas temperature in circumstellar disks around A stars [PDF]
Astronomy & Astrophysics, 2001 In circumstellar disks or shells it is often assumed that gas and dust temperatures are equal where the latter is determined by radiative equilibrium. This paper deals with the question whether this assumption is applicable for tenous circumstellar disks around young A stars. In this paper the thin hydrostatic equilibrium models described by Kamp &
Kamp, I., Zadelhoff, G.-J. van
openaire +5 more sources
Astronomy & Astrophysics, 2018 10 pages, 8 figures, 8 ...
Kiefer, Flavien +7 more
core +4 more sources
Fe I in the β Pictoris circumstellar gas disk [PDF]
Astronomy & Astrophysics, 2017 The young planetary system β Pictoris is surrounded by a circumstellar disk of dust and gas. Because both dust and gas have a lifetime shorter than the system age, they need to be replenished continuously. The gas composition is partly known, but its location and its origin are still a puzzle. The gas source could be the exocomets (or so-called falling
Vidal-Madjar, A. +7 more
openaire +4 more sources
The composition of circumstellar gas and dust in 51 Oph [PDF]
Astronomy & Astrophysics, 2001 4 pages, 3 figures, accepted by A&A (letters)
Cami, J +14 more
openaire +5 more sources
The Flash Ionization of the Circumstellar Gas of SN 1987A
AIP Conference Proceedings, 2007 The photons from the shock breakout of SN 1987A ionized the gas they encountered in less than a few hours. Twenty years later the recombining circumstellar gas is still glowing. Here we discuss what the analysis of this emission has revealed about the structure and properties of the circumstellar gas, as well as about the properties of the shock ...
Peter Lundqvist +2 more
openaire +2 more sources
Dynamics of cold circumstellar gas in debris discs
Monthly Notices of the Royal Astronomical SocietyABSTRACT Mounting observational evidence indicates that cold circumstellar gas is present in debris disc systems. This work focuses on various dynamical processes that debris disc gas may undergo. We review five mechanisms that can transport angular momentum and their applications to debris discs.
Can Cui +3 more
core +8 more sources
, 2014 From the very early observations completed in 1984, it was clear that some gas was present in the circumstellar environment. In particular the CaII lines were showing very strong absorption signatures never observed in the local ISM toward similarly nearby stars. From the comparison of the two first observations of these lines it became also clear that
Vidal-Majar, A.
openaire +2 more sources