A high-resolution survey of interstellar NA I D1 lines

Welty, D. E.; Hobbs, L. M.; Kulkarni, Varsha P.

doi:10.1086/174889

Cited by 163 publications

(211 citation statements)

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“…The solar values have been taken from Grevesse et al (1996). Abundances for the following additional elements, which have also been studied in λ Bootis stars, are available: C, N, Na (Welty et al 1994), Al, Ca, Ti, Cr, Mn, Co, Ni, Cu. For Na, only absorption lines of the neutral element have been studied, whereas Table 3.…”

Section: Comparison With the Interstellar Mediummentioning

confidence: 99%

The accretion/diffusion theory forλ Bootis stars in the light of spectroscopic data

Heiter

Weiß

Paunzen

2002

A&A

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Abstract. Most of the current theories suggest the λ Bootis phenomenon to originate from an interaction between the stellar surface and its local environment. In this paper, we compare the abundance pattern of the λ Bootis stars to that of the interstellar medium and find larger deficiencies for Mg, Si, Mn and Zn than in the interstellar medium. A comparison with metal poor post-AGB stars showing evidence for circumstellar material indicates a similar physical process possibly being at work for some of the λ Bootis stars, but not for all of them. Despite the fact that the number of spectroscopically analysed λ Bootis stars has considerably increased in the past, a test of predicted effects with observations shows current abundance and temperature data to be still controversial.

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Section: Comparison With the Interstellar Mediummentioning

confidence: 99%

The accretion/diffusion theory forλ Bootis stars in the light of spectroscopic data

Heiter

Weiß

Paunzen

2002

A&A

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“…Conversion between Na i and H i column densities at the values measured in this work is uncertain, and N(Na i) does not reliably predict N(H i) (see the discussion of Welty, Hobbs, & Kulkarni 1994). The Na i ion reliably predicts the total amount of H i in cold and neutral clouds, in which log NðNa iÞ > 11:0 cm À2 .…”

Section: The Ensemble Of Clouds In the Region Exploredmentioning

confidence: 72%

Kinematical Structure of the Local Interstellar Medium: The Galactic Anticenter Hemisphere

Genova

Beckman

2003

ASTROPHYS J SUPPL S

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A survey of interstellar Na i D1 and D2 absorption features in the spectra of 104 early-type stars in the second and third Galactic quadrants reveals the large-scale kinematics of the interstellar gas within the Galactic anticenter hemisphere at distances from the Sun between $70 and $250 pc. Employing a technique that uses both the radial velocities and column densities of the Na i absorptions produced by the intervening gas we have identified the velocity vectors and determined the spatial distribution of eight interstellar clouds in the volume explored. The average internal H i + H 2 densities of the clouds range between 0.03 and 1.7 cm À3 , and their masses between 80 and 10 4 M , although uncertainties in the sizes of the clouds, their possible extension beyond the region explored, and the presence of denser gas embedded in the larger clouds imply that these will tend to be lower limits. We have clearly identified clumps of denser gas immersed in the lowdensity gas in one of the clouds; these clumps show internal H i + H 2 densities of order 50 cm À3 . Although we are not able to detect any interstellar Na i within 70 pc, the sizes of some of the clouds imply that their near edges are within that range of distances from the Sun.With respect to the local standard of rest the clouds move with velocities between 19 and 54 km s À1 . Their velocity vectors do not support the view of a local interstellar medium uniquely dominated by expansion from centers in the Scorpio-Centaurus OB association; our results suggest that this expansion is present in the Galactic center hemisphere but in the Galactic anticenter hemisphere is restricted to the immediate neighborhood of the Sun.

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“…The correlation found between the H i and Na column densities derived from Na-D absorption lines by Ferlet et al (1985) was doubted by Welty et al (1994), especially for low column densities (log N(N aI) < 11). The region of the Lallement cube that should not be used because it has such low column densities is indicated in Fig.…”

Section: The Inhomogeneously Distributed Ismmentioning

confidence: 99%

“…Then we proceed to a few of the rare neutron stars with well known distances, having also small error bars for the absorbing N(H) derived by X-ray observations. As Hakkila et al (1997) note, different studies do not agree precisely with each other due to the various applied Hobbs et al (1988); a log(N(Nai)) = 10.6 < 11 Ferlet et al (1985) formula was doubted by Welty et al (1994) Kharchenko et al (2005a,b). To convert the reddening E(B −V ) we apply the formula by Paresce (1984): N (H) = 5.5 × 10 21 E(B − V ) cm −2 .…”

Section: Testing the Models And Further Improvementsmentioning

confidence: 99%

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The Magnificent Seven in the dusty prairie

Posselt

Попов

Haberl

et al. 2007

Isolated Neutron Stars: From the Surface to the Interior

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The Magnificent Seven have all been discovered by their exceptional soft X-ray spectra and high ratios of X-ray to optical flux. They all are considered to be nearby sources. Searching for similar objects with larger distances, one expects larger interstellar absorption resulting in harder X-ray counterparts. Current interstellar absorption treatment depends on chosen abundances and scattering cross-sections of the elements as well as on the 3D distribution of the interstellar medium. After a discussion of these factors we use the comprehensive 3D measurements of the Local Bubble by Lallement et al. (2003) to construct two simple models of the 3D distribution of the hydrogen column density. We test these models by using a set of soft X-ray sources with known distances. Finally, we discuss possible applications for distance estimations and population synthesis studies.

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A high-resolution survey of interstellar NA I D1 lines

Cited by 163 publications

References 0 publications

The accretion/diffusion theory forλ Bootis stars in the light of spectroscopic data

The accretion/diffusion theory forλ Bootis stars in the light of spectroscopic data

Kinematical Structure of the Local Interstellar Medium: The Galactic Anticenter Hemisphere

The Magnificent Seven in the dusty prairie

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