- ID:
- ivo://CDS.VizieR/J/MNRAS/427/3209
- Title:
- Galactic and MC O-AGBs and RSGs stars
- Short Name:
- J/MNRAS/427/3209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the occurrence of crystalline silicates in oxygen-rich evolved stars across a range of metallicities and mass-loss rates. It has been suggested that the crystalline silicate feature strength increases with increasing mass-loss rate, implying a correlation between lattice structure and wind density. To test this, we analyse Spitzer Infrared Spectrograph and Infrared Space Observatory Short Wavelength Spectrometer spectra of 217 oxygen-rich asymptotic giant branch and 98 red supergiants in the Milky Way, the Large and Small Magellanic Clouds, and Galactic globular clusters. These encompass a range of spectral morphologies from the spectrally rich which exhibit a wealth of crystalline and amorphous silicate features to 'naked' (dust-free) stars. We combine spectroscopic and photometric observations with the GRAMS grid of radiative transfer models to derive (dust) mass-loss rates and temperature. We then measure the strength of the crystalline silicate bands at 23, 28 and 33{mu}m. We detect crystalline silicates in stars with dust mass-loss rates which span over 3dex, down to rates of ~10^-9^M_{sun}_/yr. Detections of crystalline silicates are more prevalent in higher mass-loss rate objects, though the highest mass-loss rate objects do not show the 23-{mu}m feature, possibly due to the low temperature of the forsterite grains or it may indicate that the 23-{mu}m band is going into absorption due to high column density. Furthermore, we detect a change in the crystalline silicate mineralogy with metallicity, with enstatite seen increasingly at low metallicity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/3671
- Title:
- Galactic bubble infrared fluxes
- Short Name:
- J/MNRAS/473/3671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present the first extended catalogue of far-infrared fluxes of Galactic bubbles. Fluxes were estimated for 1814 bubbles, defined here as the 'golden sample', and were selected from the Milky Way Project First Data Release (Simpson et al., 2012MNRAS.424.2442S, Cat. J/MNRAS/424/2442) The golden sample was comprised of bubbles identified within the Wide-field Infrared Survey Explorer (WISE) dataset (using 12- and 22-um images) and Herschel data (using 70-, 160-, 250-, 350- and 500-um wavelength images). Flux estimation was achieved initially via classical aperture photometry and then by an alternative image analysis algorithm that used active contours. The accuracy of the two methods was tested by comparing the estimated fluxes for a sample of bubbles, made up of 126 HII regions and 43 planetary nebulae, which were identified by Anderson et al. The results of this paper demonstrate that a good agreement between the two was found. This is by far the largest and most homogeneous catalogue of infrared fluxes measured for Galactic bubbles and it is a step towards the fully automated analysis of astronomical datasets.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A76
- Title:
- Galactic bulge extremely reddened AGB
- Short Name:
- J/A+A/579/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extremely reddened asymptotic giant branch stars (AGB) lose mass at high rates of >10^-5^M_{sun}_/yr. This is the very last stage of AGB evolution, in which stars in the mass range ~2.0-4.0M_{sun}_ (for solar metallicity) should have been converted to C stars already. The extremely reddened AGB stars in the Galactic bulge are however predominantly O-rich, implying that they might be either low-mass stars or stars at the upper end of the AGB mass range. Our goal is to determine the mass range of the most reddened AGB stars in the Galactic bulge. Using Virtual Observatory tools, we constructed spectral energy distributions of a sample of 37 evolved stars in the Galactic bulge with extremely red IRAS colours. We fitted DUSTY models to the observational data to infer the bolometric fluxes. Applying individual corrections for interstellar extinction and adopting a common distance, we determined luminosities and mass-loss rates, and inferred the progenitor mass range from comparisons with AGB evolutionary models. The observed spectral energy distributions are consistent with a classification as reddened AGB stars, except for two stars, which are proto-planetary nebula candidates. For the AGB stars, we found luminosities in the range ~3000-30000L_{sun}_ and mass-loss rates ~10^-5^-3x10^-4^M_{sun}_/yr. The corresponding mass range is ~1.1-6.0M_{sun}_ assuming solar metallicity. Contrary to the predictions of the evolutionary models, the luminosity distribution is continuous, with many O-rich AGB stars in the mass range in which they should have been converted into C stars already. We suspect that bulge AGB stars have higher than solar metallicity and therefore may avoid the conversion to C-rich. The presence of low-mass stars in the sample shows that their termination of the AGB evolution also occurs during a final phase of very high mass-loss rate, leading to optically thick circumstellar shells.
- ID:
- ivo://CDS.VizieR/J/MNRAS/438/2839
- Title:
- Galactic Bulge Survey X-ray sources NIR ctp
- Short Name:
- J/MNRAS/438/2839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the near-infrared matches, drawn from three surveys, to the 1640 unique X-ray sources detected by Chandra in the Galactic Bulge Survey (GBS). This survey targets faint X-ray sources in the bulge, with a particular focus on accreting compact objects. We present all viable counterpart candidates and associate a false alarm probability (FAP) to each near-infrared match in order to identify the most likely counterparts. The FAP takes into account a statistical study involving a chance alignment test, as well as considering the positional accuracy of the individual X-ray sources. We find that although the star density in the bulge is very high, ~90 per cent of our sources have an FAP<10 per cent, indicating that for most X-ray sources, viable near-infrared counterparts candidates can be identified. In addition to the FAP, we provide positional and photometric information for candidate counterparts to ~95 per cent of the GBS X-ray sources. This information in combination with optical photometry, spectroscopy and variability constraints will be crucial to characterize and classify secure counterparts.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/82
- Title:
- Galactic carbon stars infrared spectroscopy
- Short Name:
- J/ApJ/887/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New infrared spectra of 33 Galactic carbon stars from FORCAST on SOFIA reveal strong connections between stellar pulsations and the dust and molecular chemistry in their circumstellar shells. A sharp boundary in overall dust content, which predominantly measures the amount of amorphous carbon, separates the semiregular and Mira variables, with the semiregulars showing little dust in their spectra and the Miras showing more. In semiregulars, the contribution from SiC dust increases rapidly as the overall dust content grows, but in Miras, the SiC dust feature grows weaker as more dust is added. A similar dichotomy is found with the absorption band from CS at ~7.3{mu}m, which is generally limited to semiregular variables. Observationally, these differences make it straightforward to distinguish semiregular and Mira variables spectroscopically without the need for long-term photometric observations or knowledge of their distances. The rapid onset of strong SiC emission in Galactic carbon stars in semiregular variables points to a different dust-condensation process before strong pulsations take over. The break in the production of amorphous carbon between semiregulars and Miras seen in the Galactic sample is also evident in Magellanic carbon stars, linking strong pulsations in carbon stars to the strong mass-loss rates which will end their lives as stars across a wide range of metallicities.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A44
- Title:
- Galactic center CO rot-vib absorption lines
- Short Name:
- J/A+A/626/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the near- to mid-infrared wavelength domain, bright continuum sources in the central parsec of the Galactic center (GC) are subject to foreground absorption. These sources therefore represent ideal probes of the intervening material that is responsible for the absorption along the line of sight. Our aim is to shed light on the location and physics of the absorbing clouds. We try to find out which of the gaseous absorbing materials is intimately associated with the GC and which one is associated with clouds at a much larger distance. We used the capabilities of CRIRES spectrograph located at ESO Very Large Telescope in Chile to obtain absorption spectra of individual lines at a high spectral resolution of R=65000, that is, 5km/s. We observed the 12CO R(0), P(1), P(2), P(3), P(4), P(5), P(6), P(7) and P(9) transition lines, applied standard data reduction, and compared the results with literature data. Results. We present the results of CRIRES observations of 13 infrared sources located in the central parsec of the Galaxy. The data provide direct evidence for a complex structure of the interstellar medium along the line of sight and in the close environment of the central sources. In particular we find four cold foreground clouds at radial velocities vLS R of the order of -145, -85, -60, and -40+\/-15km/s that show absorption in the lower transition lines from R(0) to P(2) and in all the observed spectra.We also find in all sources an absorption in velocity range of 50-60km/s, possibly associated with the so-called 50km/s cloud and suggesting an extension of this cloud in front of the GC. Finally, we detect individual absorption lines that are probably associated with material much closer to the center and with the sources themselves, suggesting the presence of cold gas in the local region.
- ID:
- ivo://CDS.VizieR/J/A+A/493/785
- Title:
- Galactic disk stellar populations from ISOGAL
- Short Name:
- J/A+A/493/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15um towards a field (LN45) in the direction l=-45, b=0.0. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory were characterised based on colour-colour and colour-magnitude diagrams. We combine the ISOGAL catalogue with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance were estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes were thus derived and the stellar populations identified from their absolute magnitudes and their infrared excess. A standard approach to analysing the ISOGAL disc observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16deg^2^. An overdensity of stellar sources is found at distances corresponding to the distance of the Scutum-Crux spiral arm. In addition, we determined mass-loss rates of AGB-stars using dust radiative transfer models from the literature.
- ID:
- ivo://CDS.VizieR/J/ApJ/653/1325
- Title:
- Galactic distribution of infrared dark clouds
- Short Name:
- J/ApJ/653/1325
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using ^13^CO(J=1-0) molecular line emission (112GHz) from the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (BU-FCRAO GRS), we have established kinematic distances to 313 infrared dark clouds (IRDCs) by matching the morphology of the molecular line emission in distinct velocity channels to their mid-infrared extinction.
- ID:
- ivo://CDS.VizieR/J/ApJ/680/349
- Title:
- Galactic distribution of IRDCs
- Short Name:
- J/ApJ/680/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CS(2-1) measurements toward a large sample of fourth Galactic quadrant infrared dark clouds (IRDCs) were made with the Australia Telescope National Facility Mopra telescope in order to establish their kinematic distances and Galactic distribution. Due to its large critical density, CS unambiguously separates the dense IRDCs from more diffuse giant molecular clouds. The fourth-quadrant IRDCs show a pronounced peak in their radial galactocentric distribution at R=6kpc. The first-quadrant IRDC distribution (traced by ^13^CO emission) also shows a peak, but at a galactocentric radius of R=5kpc rather than 6kpc. The reliability of the MSX IRDC catalog by Simon and coworkers is estimated by using the CS detection rate of IRDC candidates. The overall reliability is at least 58%, and increases to near 100% for high contrasts, Galactic longitudes within ~30{deg} of the Galactic center, and large mid-IR backgrounds. A significant fraction of our IRDC sample (14%) showed two CS velocity components, which probably represent two distinct IRDCs along the same line of sight.
- ID:
- ivo://CDS.VizieR/J/ApJS/235/41
- Title:
- Galactic EB stars with eccentric orbits based on ETDs
- Short Name:
- J/ApJS/235/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented with more than 2830 times of minima determined from the archived photometric data by various sky-survey projects and new photometric measurements. The systems are divided into two groups according to whether the individual system has a GCVS name or not. All the systems in both groups are further classified into three categories (D, A, and A+III) on the basis of their eclipse timing diagrams: 453 D systems showing just constantly displaced secondary minima, 139 A systems displaying only apsidal motion (AM), and 31 A+III systems exhibiting both AM and light-time effects. AM parameters for 170 systems (A and A+III systems) are consistently calculated and cataloged with basic information for all systems. Some important statistics for the AM parameters are discussed and compared with those derived for the eccentric EB systems in the Large and Small Magellanic Clouds.
