An ultra-high-resolution study of the interstellar medium towards Orion

Price, Richard J.; Crawford, Ian; Barlow, M. J.; Howarth, I. D.

doi:10.1046/j.1365-8711.2001.04893.x

Cited by 34 publications

(45 citation statements)

References 72 publications

(146 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The bottom panels show the telluric absorption spectrum calculated with ATRAN package software ( Lord 1992). System z abs Because the physical distance ($1 kpc) between A and B at z $ 1 is much larger than the typical spatial scale of Na i clouds in our Galaxy (a few tens to several thousands of AU; e.g., Price et al 2001), the images A and B are most likely covered unequally. This introduces an additional systematic uncertainty in the inferred properties of the Na i clouds.…”

Section: Resultsmentioning

confidence: 99%

“…Since there is a well-established correlation between N Na i and N H i (Ferlet et al 1985;Bowen et al 1995), Na i absorption, which has been observed extensively in the Galaxy, holds the potential to estimate N H i for individual clouds in DLAs, which usually cannot be precisely measured because of heavy blending of H i absorption. Moreover, the column density ratio of Na i to Ca ii provides a useful indicator of the degree of dust depletion of ISM clouds (e.g., Welsh et al 1990;Crawford 1992;Bertin et al 1993;Sembach et al 1993;Price et al 2001;Crawford et al 2002) because sodium is hardly depleted from gas onto dust, while calcium can be heavily depleted (Savage & Sembach 1996).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

First Detection of NaiD Lines in High‐Redshift Damped Lyα Systems

Kondo

Kobayashi

Minowa

et al. 2006

ApJ

View full text Add to dashboard Cite

An NIR (1.18-1.35 m) high-resolution spectrum of the gravitationally lensed QSO APM 08279+5255 was obtained with the Subaru Telescope IRCS using the AO system. We have detected strong Na i D kk5891, 5897 doublet absorption in high-redshift DLAs at z abs ¼ 1:062 and 1.181, confirming the presence of Na i, which was first reported for the rest-frame UV Na i kk3303.3, 3303.9 doublet by Petitjean et al. This is the first detection of Na i D absorption in a high-redshift (z > 1) DLA. We have also detected a new Na i component in the z abs ¼ 1:062 DLA and four new components in the z abs ¼ 1:181 DLA. Using an empirical relationship between Na i and H i column density, we found that all components have large H i column density ( log N H i ½cm À2 k 20:3), so each component is classified as DLA absorption. We also detected strong Na i D absorption associated with a Mg ii system at z abs ¼ 1:173. Because no other metal absorption lines were detected in this system at the velocity of the Na i absorption in previously reported optical spectra, we infer that this Na i absorption cloud probably appeared in the line of sight toward the QSO after the optical observation. This newly found cloud is likely to be a DLA based on its large estimated H i column density. We found that the N Na i /N Ca ii ratios in these DLAs are systematically smaller than those observed in the Galaxy; they are more consistent with the ratios seen in the LMC. This is consistent with dust depletion generally being smaller in lower metallicity environments. However, all five clouds of the z abs ¼ 1:181 system have a high N Na i /N Ca ii ratio, which is characteristic of cold dense gas. We tentatively suggest that the host galaxy of this system may be the most significant contributor to the gravitational lens toward APM 08279+5255.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First Detection of NaiD Lines in High‐Redshift Damped Lyα Systems

Kondo

Kobayashi

Minowa

et al. 2006

ApJ

View full text Add to dashboard Cite

show abstract

“…However, the Price et al (2001) Copernicus was unable to detect H 2 in the Veil, setting an upper limit of log ½N (H 2 ) 17:55 (Savage et al 1977). In the diffuse interstellar medium (ISM ), the observed reddening along this line of sight, E(B À V ) ¼ 0:32 (Bohlin & Savage 1981) is usually associated with H 2 column densities 2-3 orders of magnitude higher than those observed by Copernicus.…”

Section: Opticalmentioning

confidence: 97%

“…The most recent and highest resolution study is that by Price et al (2001). They observed Ca ii, Na i, K i, CH, and CH + optical absorption lines at many positions in the Veil.…”

Section: Opticalmentioning

confidence: 99%

Physical Conditions in Orion’s Veil. II. A Multicomponent Study of the Line of Sight toward the Trapezium

Abel

Ferland

O’Dell

et al. 2006

ApJ

View full text Add to dashboard Cite

Orion's Veil is an absorbing screen that lies along the line of sight to the Orion H ii region. It consists of two or more layers of gas that must lie within a few parsecs of the Trapezium cluster. Our previous work considered the Veil as a whole and found that the magnetic field dominates the energetics of the gas in at least one component. Here we use high-resolution STIS UV spectra that resolve the two velocity components in absorption and determine the conditions in each. We derive a volume hydrogen density, 21 cm spin temperature, turbulent velocity, and kinetic temperature for each. We combine these estimates with magnetic field measurements to find that magnetic energy significantly dominates turbulent and thermal energies in one component, while the other component is close to equipartition between turbulent and magnetic energies. We observe H 2 absorption for highly excited v, J levels that are photoexcited by the stellar continuum, and detect blueshifted S +2 and P +2 ions. These ions must arise from ionized gas between the mostly neutral portions of the Veil and the Trapezium and shields the Veil from ionizing radiation. We find that this layer of ionized gas is also responsible for He i k3889 absorption toward the Veil, which resolves a 40 year old debate on the origin of He i absorption toward the Trapezium. Finally, we determine that the ionized and mostly atomic layers of the Veil will collide in less than 85,000 yr.

show abstract

“…Later years saw a lot of research concerning the interstellar absorptions lines, e.g. Welty & Hobbs (2001), Crawford (2001), Price et al (2001), Crawford et al (2002), Smoker et al (2003), Welty et al (2003), Hunter et al (2006), Smoker et al (2006), to name just the more recent ones. However, the possible use of these spectral features for distance estimation was hampered by problems with the calibration of the distance -line strength relation, because of the necessity of finding a substantial sample of appropriately distant stars with well determined distances.…”

Section: Introductionmentioning

confidence: 99%

The interstellar Ca II distance scale

Megier

Strobel

Галазутдинов

et al. 2009

A&A

100

View full text Add to dashboard Cite

Aims. We attempt to extend the relation between the strengths of the interstellar Ca ii lines and the distances to early-type stars to objects beyond 1 kiloparsec, with the line saturation taken into account.Methods. We measure the Ca ii K and Ca ii H equivalent widths, and compute Ca ii column densities for 262 lines of sight towards early-type stars with available Hipparcos parallaxes (π). The targets are located within a few hundred parsecs of the Galactic plane, and span all the range of Galactic longitudes. We fit the N Ca ii -parallax relation with a function of the form π = 1/(a · N Ca ii + b), using a maximum-likelihood approach to take account of errors in both variables. We use the resultant formula to estimate distances to stars in OB associations and clusters, and compare them to those found in the literature, usually estimated by spectrophotometric methods. 1.3, we obtain the following approximate formula for the distance: D Ca ii = 77 + (2.78 + Results. For lines of sight with EW(K)/EW(H) > EW(K) EW(H) −0.932 )EW(H), where the equivalent widths EW(K) and EW(H) are in mÅ, and the distance D Ca ii in parsecs.The errors in D Ca ii , resulting from the uncertainty in the fit parameters and errors in the equivalent widths, are typically about 15% of the distance. We can also expect the equation not to hold for objects situated farther than a few hundred parsecs from the Galactic plane. We find several cases of significant column density differences between association or cluster members, especially notable in the Trumpler 16 cluster, indicating either a local contribution to the Ca ii column density, or background/foreground stars being confused with members. The ratio D Ca ii /D assoc appears to depend on the Galactic longitude, being highest in the range 70 • < l < 120 • and lowest for 200 • < l < 300 • . This effect may be due to large-scale structure being present in the Ca ii layer, or to the nonmember confusion being enhanced in these directions.

show abstract

An ultra-high-resolution study of the interstellar medium towards Orion

Cited by 34 publications

References 72 publications

First Detection of NaiD Lines in High‐Redshift Damped Lyα Systems

First Detection of NaiD Lines in High‐Redshift Damped Lyα Systems

Physical Conditions in Orion’s Veil. II. A Multicomponent Study of the Line of Sight toward the Trapezium

The interstellar Ca II distance scale

Contact Info

Product

Resources

About