- ID:
- ivo://CDS.VizieR/J/A+A/349/L69
- Title:
- Interstellar extinction
- Short Name:
- J/A+A/349/L69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DENIS observations in the J(1.25{mu}m) and K_S_(2.15{mu}m) bands together with isochrones calculated for the RGB and AGB phase are used to draw an extinction map of the inner Galactic Bulge. The uncertainty in this method is mainly limited by the optical depth of the Bulge itself. A comparison with fields of known extinction shows a very good agreement. We present an extinction map for the inner Galactic Bulge (~20{deg}^2^)
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Search Results
- ID:
- ivo://CDS.VizieR/J/BaltA/11/1
- Title:
- Interstellar extinction curves of OB stars
- Short Name:
- J/BaltA/11/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper presents a collection of 436 extinction curves covering the whole available range of wavelengths from satellite UV to near-IR. The data were taken from the ANS photometric catalogue (Cat. <II/97>) and from the compilations of IR photometric measurements. The data curves have been obtained with the aid of "artificial standards" Papaj et al. (1993A&A...273..575P) and Wegner (1994MNRAS.270..229W, 1995, Interstellar Absorption Structures in the Direction of Nearby OB stars, Wyd. Uczelniane WSP, Bydgoszcz, p. 1-383). The visual magnitudes and spectral classifications of O and B type stars with E_B-V_>=0.05 were taken from the SIMBAD database. The curves are given in the form of plots and tables E_{lambda}-V_/E_B-V_ versus 1/{lambda}. The observed variety of extinction laws among slightly reddened stars is apparently due to the various physical parameters of interstellar clouds.
- ID:
- ivo://CDS.VizieR/III/148A
- Title:
- Interstellar lines catalogue
- Short Name:
- III/148A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A bibliographical catalogue of the interstellar lines has been prepared (2003 stars in our Galaxy, 86 stars in the Magellanic Clouds and 41 extragalactic objects), and 371 bibliographical references.
- ID:
- ivo://CDS.VizieR/J/A+A/411/447
- Title:
- Interstellar NaI D-line
- Short Name:
- J/A+A/411/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present intermediate results from a long-term program of mapping the neutral absorption characteristics of the local interstellar medium, motivated by the availability of accurate and consistent parallaxes from the Hipparcos satellite. Equivalent widths of the interstellar NaI D-line doublet at 5890{AA} are presented for the lines-of-sight towards some 311 new target stars lying within ~350pc of the Sun. Using these data, together with NaI absorption measurements towards a further ~240 nearby targets published in the literature (for many of them, in the directions of molecular clouds), and the ~450 lines-of-sight already presented by (Sfeir et al., 1999, Cat. <J/A+A/346/785>), we show 3D absorption maps of the local distribution of neutral gas towards 1005 sight-lines with Hipparcos distances as viewed from a variety of different galactic projections. The data are synthesized by means of two complementary methods, (i) by mapping of iso-equivalent width contours, and (ii) by density distribution calculation from the inversion of column-densities, a method devised by Vergely et al. (2001A&A...366.1016V). Our present data confirms the view that the local cavity is deficient in cold and neutral interstellar gas. The closest dense and cold gas "wall", in the first quadrant, is at ~55-60pc. There are a few isolated clouds at closer distance, if the detected absorption is not produced by circumstellar material. The observations were obtained during 11 observing runs over the period 1998-2000.
- ID:
- ivo://CDS.VizieR/J/ApJS/145/355
- Title:
- Interstellar NaI lines toward anticenter
- Short Name:
- J/ApJS/145/355
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey of interstellar NaI 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 ~250pc. Employing a technique that uses both the radial velocities and column densities of the NaI 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/1478
- Title:
- Interstellar NaI, TiII & CaIIK obs.
- Short Name:
- J/MNRAS/367/1478
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of interstellar NaI ({lambda}_air_=3302.37 and 3302.98{AA}), TiII ({lambda}_air_=3383.76{AA}) and CaIIK ({lambda}_air_=3933.66{AA}) absorption features for 74 sightlines towards O- and B-type stars in the Galactic disc. The data were obtained from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project (UVES POP), at a spectral resolution of 3.75km/s and with mean signal-to-noise ratios per pixel of 260, 300 and 430 for the NaI, TiII and CaII observations, respectively. Interstellar features were detected in all but one of the TiII sightlines and all of the CaII sightlines. The dependence of the column density of these three species with distance, height relative to the Galactic plane, HI column density, reddening and depletion relative to the solar abundance has been investigated. We also examine the accuracy of using the NaI column density as an indicator of that for HI. In general, we find similar strong correlations for both Ti and Ca, and weaker correlations for Na. Our results confirm the general belief that Ti and Ca occur in the same regions of the interstellar medium (ISM) and also that the TiII/CaII ratio is constant over all parameters. We hence conclude that the absorption properties of Ti and Ca are essentially constant under the general ISM conditions of the Galactic disc.
- ID:
- ivo://CDS.VizieR/J/A+A/410/905
- Title:
- Interstellar reddening parameter measurements
- Short Name:
- J/A+A/410/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new measurements of the interstellar reddening parameter R_V_=A_V_/E(B-V) towards 185 O stars, using J, H, Ks photometry from the 2MASS project. The average R_V_ from these is of 3.19+/-0.50. All objects whose R_V_ departs from this value by more than 2 sigma have been recognized. Ten objects have R_V_ higher than this value and two lower. In the Cygnus region R_V_ values follow the behaviour of the general interstellar medium, while in the Carina arm, in spite of the relatively larger distance, local cloud effects prevail. The relatively few stars of our sample whose Hipparcos parallaxes are reliable, are found to have distances systematically smaller than the distances derived by the spectroscopic parallaxes. We argue that this effect is consistent with the recently claimed discovery of grey extinction towards OB stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/241/2
- Title:
- Ionization profiles of 8 Galactic H II regions
- Short Name:
- J/ApJS/241/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Green Bank Telescope radio recombination line (RRL) data, we analyze the role of leaking radiation from HII regions in maintaining the ionization of the interstellar medium (ISM). We observed a sample of eight Galactic HII regions of various sizes, morphologies, and luminosities. For each region, the hydrogen RRL intensity decreases roughly as a power-law with the distance from the center of the region. This suggests that radiation leaking from the HII region is responsible for the majority of surrounding ionized gas producing RRL emission. Our results further indicate that the hydrogen RRL intensity appears to be fundamentally related to the HII region sizes traced by their photodissociation regions, such that physically smaller HII regions show a steeper decrease in intensity with an increasing distance from the region centers. As a result, giant HII regions may have a much larger effect in maintaining the ionization of the ISM. For six of the eight observed HII regions, we find a decrease in the ^4^He^+^/H^+^ abundance ratio with an increasing distance, indicating that He-ionizing photons are being absorbed within the ionization front of the HII region. There is enhanced carbon RRL emission toward directions with strong continuum background, suggesting that the carbon emission is amplified by stimulated emission.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A17
- Title:
- IRAM spectra toward M33 Giant Molecular Clouds
- Short Name:
- J/A+A/549/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to better understand the emission of molecular tracers of the diffuse and dense gas in giant molecular clouds and the influence that metallicity, optical extinction, density, far-UV field, and star formation rate have on these tracers. Using the IRAM 30m telescope, we detected HCN, HCO^+^, ^12^CO, and ^13^CO in six GMCs along the major axis of M33 at a resolution of ~114pc and out to a radial distance of 3.4kpc. Optical, far-infrared, and submillimeter data from Herschel and other observatories complement these observations. To interpret the observed molecular line emission, we created two grids of models of photon-dominated regions, one for solar and one for M33-type subsolar metallicity. The observed HCO^+^/HCN line ratios range between 1.1 and 2.5. Similarly high ratios have been observed in the Large Magellanic Cloud. The HCN/CO ratio varies between 0.4% and 2.9% in the disk of M33. The ^12^CO/^13^CO line ratio varies between 9 and 15 similar to variations found in the diffuse gas and the centers of GMCs of the Milky Way. Stacking of all spectra allowed HNC and C_2_H to be detected. The resulting HCO^+^/HNC and HCN/HNC ratios of ~8 and 6, respectively, lie at the high end of ratios observed in a large set of (ultra-)luminous infrared galaxies. HCN abundances are lower in the subsolar metallicity PDR models, while HCO^+^ abundances are enhanced. For HCN this effect is more pronounced at low optical extinctions. The observed HCO^+^/HCN and HCN/CO line ratios are naturally explained by subsolar PDR models of low optical extinctions between 3 and 10mag and of moderate densities of n=3x10^3^-3x10^4^cm^-3^, while the FUV field strength only has a small effect on the modeled line ratios. The line ratios are almost equally well reproduced by the solar-metallicity models, indicating that variations in metallicity only play a minor role in influencing these line ratios.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A137
- Title:
- IRAS 16293-2422 CH_3_CCH spectral cubes
- Short Name:
- J/A+A/631/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Propyne (CH_3_CCH) has been detected in a variety of environments, from Galactic star-forming regions to extragalactic sources. Such molecules are excellent tracers of the physical conditions in star-forming regions. This study explores the emission of CH_3_CCH in the low-mass protostellar binary, IRAS 16293-2422, examining the spatial scales traced by this molecule, as well as its formation and destruction pathways. ALMA observations from the Protostellar Interferometric Line Survey (PILS) are used to determine the abundances and excitation temperatures of CH_3_CCH towards both protostars, exploring spatial scales from 70 to 2400au. The three-phase chemical kinetics model MAGICKAL is also used, to explore the chemical reactions of this molecule. CH_3_CCH is detected towards both IRAS 16293A and IRAS 16293B and is found to trace the hot corino component around each source in the PILS dataset. Eighteen transitions above 3{sigma} are detected, enabling robust excitation temperatures and column densities to be determined in each source. In IRAS 16293A, an excitation temperature of 90K and a column density of 7.8x10^15^cm^-2^ best fits the spectra. In IRAS 16293B, an excitation temperature of 100K and 6.8x10^15^cm^-2^ best fits the spectra. The chemical modelling finds that in order to reproduce the observed abundances, both gas-phase and grain-surface reactions are needed. CH_3_CCH is a molecule whose brightness and abundance in many different regions can be utilised to provide a benchmark of molecular variation with the physical properties of star-forming regions. It is essential when making such comparisons, that the abundances are determined with a good understanding of the spatial scale of the emitting region, to ensure that accurate abundances are derived
