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

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

scholarly journals The Deuterium Abundance in the Local Interstellar Medium

1992 ◽  
Vol 9 ◽  
pp. 455-458
Author(s):  
Jeffrey L. Linsky
Keyword(s):  
Binary System ◽  
Interstellar Medium ◽  
Line Of Sight ◽  
High Signal ◽  
Local Interstellar Medium ◽  
Signal Noise ◽  
Spectroscopic Binary

AbstractAccurate measurements of the interstellar deuterium/hydrogen ratio along different lines of sight are needed to test predictions of contemporary cosmologies. I describe our GHRS observations of the Lyman-α, 2600 Å and 2800 Å spectral regions for the spectroscopic binary system Capella, obtained with 3.57 km s resolution and high signal/noise. We are now analyzing these data to infer the column densities of H I, D I, Mg II, and Fe II along this 13 pc line of sight.

scholarly journals The Interstellar and Circumstellar Environment of White Dwarfs

1997 ◽  
Vol 166 ◽  
pp. 69-74
Author(s):  
M.A. Barstow ◽  
P.D. Dobbie ◽  
J.B. Holberg
Keyword(s):  
Interstellar Medium ◽  
White Dwarfs ◽  
Column Density ◽  
Line Of Sight ◽  
Local Distribution ◽  
Local Interstellar Medium ◽  
Weighted Mean ◽  
Ionization Fraction ◽  
Absorbing Material ◽  
Circumstellar Environment

AbstractWe have studied the EUV spectra of 13 DA white dwarfs, observed by the EUVE satellite, paying attention to the possible sources of absorbing material along the lines-of-sight in both the local interstellar medium and in the photospheres of the stars themselves. The range of interstellar column densities seen are consistent with our previous understanding of the local distribution of material. Absorption from interstellar He II is found in the direction of five stars, allowing us to measure directly the He ionization fraction and estimate, indirectly, that of H. The weighted mean ionization fractions along these lines-of-sight are 0.27 ± 0.04 and 0.35 ± 0.1 respectively. Where He II is directly detected, the observed ionization fractions are not correlated with direction or with the volume/column density of material along the line-of-sight. Furthermore, the limits on the amount of He II established in all other directions completely encompass the range of observed values. Indeed, all the data can be consistent with more or less constant He and H ionization fractions throughout the local ISM. However, observation of very hot DA stars, indicating higher He II columns, might contradict this picture if the material is not photospheric or circumstellar.

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 Dust towards the Galactic Centre

1989 ◽  
Vol 135 ◽  
pp. 47-54
Author(s):  
D. K. Aitken
Keyword(s):  
Interstellar Medium ◽  
Line Of Sight ◽  
Galactic Centre ◽  
Dust Grains ◽  
Local Interstellar Medium ◽  
Dust Extinction ◽  
Polarized Emission ◽  
Central Regions

The observed infrared properties of dust extinction along the line of site to the Galactic Centre are compared with those in the local interstellar medium. Further constraints on the nature of the dust grains are provided by polarimetric observations, which also lead to information on the stratification of the material along the line of sight. Finally some implications of the large polarized emission seen from the central regions are discussed.

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