scholarly journals Atomic and Molecular Interstellar Absorption Lines toward the High Galactic Latitude Stars HD 141569 and HD 157841 at Ultra–High Resolution

1998 ◽  
Vol 504 (1) ◽  
pp. 522-532 ◽  
Author(s):  
M. S. Sahu ◽  
J. C. Blades ◽  
L. He ◽  
Dap Hartmann ◽  
M. J. Barlow ◽  
...  
Keyword(s):  
High Resolution ◽  
Absorption Lines ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Interstellar Absorption

scholarly journals Wave Structure within HI Filaments at High Galactic Latitude and the Nature of “Clouds” in Interstellar Space

1991 ◽  
Vol 144 ◽  
pp. 93-96
Author(s):  
Gerrit L. Verschuur
Keyword(s):  
High Resolution ◽  
High Latitude ◽  
High Velocity ◽  
Large Amplitude ◽  
Wave Structure ◽  
Interstellar Space ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Field Geometry ◽  
High Velocity Clouds

Large amplitude waves have been found in the morphology and velocity patterns of several long filaments of HI at high latitude. HI in the filaments is controlled by magnetic fields and the velocity patterns and morphology bear the hallmarks of Alfvén waves. Enhanced emission features (EEFs), traditionally referred to as “clouds,” are seen wherever a segment of flux tube is viewed end-on. This suggests that HI emission structure teaches us about field geometry and not about cloud physics. Similar effects have been recognized in other regions mapped with high-resolution as well as in completely mapped high-velocity “clouds.”

scholarly journals Analysis of absorption lines in the high-resolution spectra of five hot post-AGB candidates

2020 ◽  
Vol 494 (2) ◽  
pp. 2117-2130
Author(s):  
A Herrero ◽  
M Parthasarathy ◽  
S Simón-Díaz ◽  
S Hubrig ◽  
G Sarkar ◽  
...  
Keyword(s):  
High Resolution ◽  
Rotational Velocity ◽  
Asymptotic Giant Branch ◽  
Absorption Lines ◽  
Binary Interaction ◽  
Strength Parameter ◽  
Galactic Latitude ◽  
History Of ◽  
Similar Temperature ◽  
Absolute Magnitudes

ABSTRACT From an analysis of absorption lines in the high-resolution spectra, we have derived the radial velocities, stellar parameters (Teff, log g, wind-strength parameter log Q, and projected rotational velocity), and abundances (C, N, O, and Si) of IRAS 17460-3114, IRAS 18131-3008, IRAS 19336-0400, LSE 45, and LSE 163. Abundances are found to be solar, except for a low Si abundance in IRAS 19336-0400 and a mild CNO pattern in LSE 163, which rotates at an unusual large rotational velocity for its spectral classification. Combining the stellar parameters information with the Gaia DR2 data, we are able to derive absolute magnitudes, radii, and luminosities and clarify the possible post-asymptotic giant branch (AGB) nature of the objects. IRAS 17460-3114 and IRAS 18131-3008 are found to be massive OB stars, whereas IRAS 19336-0400 is found to be a post-AGB star, already showing nebular lines in the spectrum. However, we could not confirm the nature of LSE 45 and LSE 163 as post-AGB stars, although their parameters are much more inconsistent with those of massive stars. In both cases, we find a discrepancy between the spectroscopic mass and that derived from the predictions of post-AGB evolutionary tracks. In addition, LSE 45 lacks nebular lines, which are present in IRAS 19336-0400 at a similar temperature. In the case of LSE 163, the rotational velocity (259 ± 15 $\rm km\, s^{-1}$) would be extremely large for a star evolving to central stars of planetary nebulae. The combination of this rotational velocity, the high Galactic latitude, slightly large radial velocity, and mild CNO enhancement suggests a history of binary interaction.

scholarly journals Interstellar Matter with Very Large Telescopes

1984 ◽  
Vol 79 ◽  
pp. 675-678
Author(s):  
J. Lequeux
Keyword(s):  
High Resolution ◽  
Absorption Lines ◽  
High Resolution Spectroscopy ◽  
Interstellar Matter ◽  
Large Telescope ◽  
Interstellar Absorption ◽  
Near Ir ◽  
Very Large Telescope ◽  
Large Telescopes ◽  
Diffuse Matter

Interstellar matter is certainly one of the fields where a very large telescope (VLT) will prove to be most fruitful. This includes (somewhat paradoxically, but this will be explained later) the study of extended emissions. I will now examine in turn the different domains of interest for a VLT.I. Neutral diffuse matterOptical and near IR observations will mainly contribute to this domain through high-resolution spectroscopy of interstellar absorption lines in the spectra of stars. These lines are resonant lines of atoms (NaI, KI, etc.) or ions (CaII, TiII, etc.) as well as of some molecules (CH+, CH, CN, CS+, C2 in the near IR). Clearly this kind of study is always photon - limited; a VLT will collect more photons than present telescopes, thus increase the possibilities considerably.

Interstellar absorption lines in high-resolution IUE spectra of cataclysmic variables

1988 ◽  
Vol 335 ◽  
pp. 829 ◽  
Author(s):  
Christopher W. Mauche ◽  
John C. Raymond ◽  
France A. Cordova
Keyword(s):  
High Resolution ◽  
Cataclysmic Variables ◽  
Absorption Lines ◽  
Interstellar Absorption

scholarly journals Ultra–High‐Resolution Observations of Interstellar Naiand CaiiK toward the High Galactic Latitude Star HD 28497

1997 ◽  
Vol 478 (2) ◽  
pp. 648-657 ◽  
Author(s):  
J. Chris Blades ◽  
M. S. Sahu ◽  
Lida He ◽  
I. A. Crawford ◽  
M. J. Barlow ◽  
...  
Keyword(s):  
High Resolution ◽  
Galactic Latitude ◽  
High Galactic Latitude
Sign in / Sign up

Export Citation Format

Share Document