High-resolution CA II observations of the local interstellar medium

1993 ◽  
Vol 411 ◽  
pp. 729 ◽  
Author(s):  
J. V. Vallerga ◽  
P. W. Vedder ◽  
N. Craig ◽  
B. Y. Welsh
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Local Interstellar Medium

scholarly journals Observations of Local Interstellar Mg I and Mg II

1984 ◽  
Vol 81 ◽  
pp. 64-66 ◽  
Author(s):  
F. Bruhweiler ◽  
W. Oegerle ◽  
E. Weiler ◽  
R. Stencel ◽  
Y. Kondo
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Upper Limits

AbstractWe have combined Copernicus and IUE observations of 5 stars within 50 pc of the Sun to study the ionization of magnesium in the local interstellar medium (LISM). The high resolution Copernicus spectrometer was used to detect interstellar Mg I 2852 in the spectra of α Gru, α Eri, and α Lyr, while placing upper limits on Mg I in the spectra of α CMa and α PsA. Observations of Mg II 2795, 2802 for these stars were also obtained with IUE and Copernicus. The column densities of Mg I and Mg II are used to place constraints on the temperature of the LISM.

Further high-resolution NA I observations of the local interstellar medium

1991 ◽  
Vol 381 ◽  
pp. 462 ◽  
Author(s):  
B. Y. Welsh ◽  
P. W. Vedder ◽  
J. V. Vallerga ◽  
N. Craig
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Local Interstellar Medium

Goddard high-resolution spectrograph observations of the local interstellar medium and the deuterium/hydrogen ratio along the line of sight toward Capella

1993 ◽  
Vol 402 ◽  
pp. 694 ◽  
Author(s):  
Jeffrey L. Linsky ◽  
Alexander Brown ◽  
Ken Gayley ◽  
Athanassios Diplas ◽  
Blair D. Savage ◽  
...  
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Line Of Sight ◽  
Local Interstellar Medium

High-resolution Na I Observations of the Local Interstellar Medium

1991 ◽  
Vol 9 (1) ◽  
pp. 122-123
Author(s):  
Barry Y. Welsh ◽  
Peter W. Vedder ◽  
John V. Vallerga
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Column Density ◽  
Velocity Structure ◽  
Extreme Ultraviolet ◽  
Sodium Absorption ◽  
Local Interstellar Medium ◽  
Neutral Gas ◽  
Hydrogen Column Density ◽  
Early Type Stars

AbstractWe present high-resolution absorption measurements (R ~ 150 000) of the interstellar Na I D-lines at 5890 Å observed towards 46 early-type stars. The distance to these stars ranges from 20–200 pc, allowing a probe of the local interstellar medium (LISM). The velocity structure, velocity dispersions and column densities of the various cloud components have been derived using an absorption line-fitting analysis. Sodium column densities have been determined for 23 of the 46 target stars. No sodium absorption was detected towards any of the stars with distances < 43 pc. Such null results imply a corresponding hydrogen column density limit, N(H), of ~ 2.5 × 1018cm−2 in many directions in the LISM. For three exceptionally vacant lines of sight (to β CMa, 36 Lyn and η Hya) this limit of low hydrogen column density can be placed out to a much further distance of > 150 pc.We have plotted the distribution of sodium column density in the LISM for a total of 118 stars in the form of three galactic maps. These maps qualitatively show that the present picture of the LISM, in which the first 50 pc is essentially free of dense clumps of neutral gas, is correct. Our map of sodium columns for stars with distances > 100 pc shows that the region within the galactic quadrant defined by 200° < l < 270° shows a conspicuous absence of any significant concentration of neutral gas. This region will be a prime direction of study for forthcoming soft X-ray and extreme ultraviolet satellite experiments.

scholarly journals White Dwarf Probes of Interstellar Deuterium

2000 ◽  
Vol 198 ◽  
pp. 485-486
Author(s):  
Wayne Landsman
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
White Dwarf ◽  
White Dwarfs ◽  
Accurate Determination ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Space Telescope ◽  
Imaging Spectrograph

We review the advantages of using hot white dwarfs (WDs) as probes of the deuterium abundance in the local interstellar medium. We then discuss advantages of the Space Telescope Imaging Spectrograph (STIS) for such observations, as compared with earlier observations with the Goddard High Resolution Spectrograph (GHRS). The GHRS Ly α profile of the white dwarf HZ 43 is probably modified by the hot ‘hydrogen wall’ surrounding the Sun; but despite this complication, the sightline remains a promising one for an accurate determination of the deuterium abundance in the local interstellar medium.

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