- ID:
- ivo://CDS.VizieR/J/ApJ/517/264
- Title:
- Extinction in the Taurus dark cloud complex
- Short Name:
- J/ApJ/517/264
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the detailed distribution of extinction in a region of the Taurus dark cloud complex. Our study uses new BVR images of the region, spectral classification data for 95 stars, and IRAS Sky Survey Atlas (ISSA) 60 and 100 {mu}m images. We study the extinction of the region in four different ways, and we present the first intercomparison of all these methods, which are as follows: (1) using the color excess of background stars for which spectral types are known, (2) using the ISSA 60 and 100 {mu}m images, (3) using star counts, and (4) using an optical (V and R) version of the average color excess method used by Lada et al. We find that all four methods give generally similar results - with important exceptions. As expected, all the methods show an increase in extinction due to dense dusty regions (i.e., dark clouds and IRAS cores) and a general increase in extinction with increasing declination, due to a larger content of dust in the northern regions of the Taurus dark cloud complex. Some of the discrepancies between the methods are caused by assuming a constant dust temperature for each line of sight in the ISSA extinction maps and not correcting for unexpected changes in the background stellar population (i.e., the presence of a cluster or Galactic gradients in the stellar density and average V-R color).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/786/113
- Title:
- Extinction law in the Cep OB3b young cluster
- Short Name:
- J/ApJ/786/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine the extinction law through Cep OB3b, a young cluster of 3000 stars undergoing gas dispersal. The extinction is measured toward 76 background K giants identified with MMT/Hectospec spectra. Color excess ratios were determined toward each of the giants using V and R photometry from the literature, g, r, i, and z photometry from the Sloan Digital Sky Survey and J, H, and K_s_ photometry from the Two Micron All Sky Survey. These color excess ratios were then used to construct the extinction law through the dusty material associated with Cep OB3b. The extinction law through Cep OB3b is intermediate between the R_V_=3.1 and R_V_=5 laws commonly used for the diffuse atomic interstellar medium and dense molecular clouds, respectively. The dependence of the extinction law on line-of-sight A_V_ is investigated and we find the extinction law becomes shallower for regions with A_V_>2.5 mag. We speculate that the intermediate dust law results from dust processing during the dispersal of the molecular cloud by the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/148/24
- Title:
- Extinction maps in the bulge from APOGEE
- Short Name:
- J/AJ/148/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic interstellar extinction maps are powerful and necessary tools for Milky Way structure and stellar population analyses, particularly toward the heavily reddened bulge and in the midplane. However, due to the difficulty of obtaining reliable extinction measures and distances for a large number of stars that are independent of these maps, tests of their accuracy and systematics have been limited. Our goal is to assess a variety of photometric stellar extinction estimates, including both two-dimensional and three-dimensional extinction maps, using independent extinction measures based on a large spectroscopic sample of stars toward the Milky Way bulge. We employ stellar atmospheric parameters derived from high-resolution H-band Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectra, combined with theoretical stellar isochrones, to calculate line-of-sight extinction and distances for a sample of more than 2400 giants toward the Milky Way bulge. We compare these extinction values to those predicted by individual near-IR and near+mid-IR stellar colors, two-dimensional bulge extinction maps, and three-dimensional extinction maps. The long baseline, near+mid-IR stellar colors are, on average, the most accurate predictors of the APOGEE extinction estimates, and the two-dimensional and three-dimensional extinction maps derived from different stellar populations along different sightlines show varying degrees of reliability. We present the results of all of the comparisons and discuss reasons for the observed discrepancies. We also demonstrate how the particular stellar atmospheric models adopted can have a strong impact on this type of analysis, and discuss related caveats.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A42
- Title:
- Extinction map towards the Galactic bulge
- Short Name:
- J/A+A/550/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine the observations with the Besancon model of the Galaxy to investigate the variations of extinction along different lines of sight towards the inner Galactic bulge as a function of distance. The full results are listed in Table 1 and Table 2. These results will be also added into the BEAM calculator webpage (http://mill.astro.puc.cl/BEAM/calculator.php). For each position we give the E(J-Ks), E(H-Ks) as well as the corresponding sigma for each distance bin starting from 1 to 10kpc.
- ID:
- ivo://CDS.VizieR/J/AN/324/219
- Title:
- Extinction of OB stars
- Short Name:
- J/AN/324/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper presents an extensive list of the total to selective extinction ratios R calculated from the infrared magnitudes of 597 O and B stars using the extrapolation method. The IR magnitudes of these stars were taken from the literature. The IR colour excesses are determined with the aid of "artificial standards", Wegner (1994MNRAS.270..229W). The individual and mean values of total to selective extinction ratios R differ in most cases from the average value R=3.10+/-0.05, Wegner (1993AcA....43..209W) in different OB associations. The relation between total to selective extinction ratios R determined in this paper and those calculated using the "method of variable extinction" and the Cardelli et al. (1989ApJ...345..245C) formulae is discussed. The R values presented in this paper can be used to determine individual absolute magnitudes of reddened OB stars with known trigonometric parallaxes.
- ID:
- ivo://CDS.VizieR/J/A+A/446/551
- Title:
- Extinctions at 7um & 15um from ISOGAL survey
- Short Name:
- J/A+A/446/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ISOGAL PSC data have been associated with near-infrared 2MASS sources, consisting a five-band photometric catalogue. In comparison with the ISOGAL-DENIS PSC catalogue, the number of fields in the ISOGAL-2MASS PSC is increased by 43 thanks to the 2MASS inclusion of the northern ISOGAL field. This point source catalogue contains all parameters of 7{mu}m or 15{mu}m from the ISOGAL PSC, together with the J H Ks bands data from the 2MASS All-Sky PSC (see the paper for a complete description). Based on the ISOGAL-2MASS PSC, the extinction laws at 7{mu}m and 15{mu}m are derived for more than 120 sightlines in the inner Galactic plane. The extinction values at 7{mu}m and 15{mu}m were in terms of the near-infrared extinction in the Ks band. The ratios that E(Ks-[7])/E(J-Ks) and E(Ks-[7])/E(Ks-[15]) are also displayed in the tables (see the paper for a complete description).
- ID:
- ivo://CDS.VizieR/J/A+A/613/A9
- Title:
- Extinction towards Galactic O stars
- Short Name:
- J/A+A/613/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- O stars are excellent tracers of the intervening ISM because of their high luminosity, blue intrinsic SED, and relatively featureless spectra. We are currently conducting the Galactic O-Star Spectroscopic Survey (GOSSS), which is generating a large sample of O stars with accurate spectral types within several kpc of the Sun. We aim to obtain a global picture of the properties of dust extinction in the solar neighborhood based on optical-NIR photometry of O stars with accurate spectral types. We have processed a carefully selected photometric set with the CHORIZOS code to measure the amount [E(4405-5495)] and type [R_5495_] of extinction towards 562 O-type stellar systems. We have tested three different families of extinction laws and analyzed our results with the help of additional archival data.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A68
- Title:
- FEDReD III: Unraveling the 3D structure of Vela
- Short Name:
- J/A+A/655/A68
- Date:
- 10 Mar 2022 07:24:47
- Publisher:
- CDS
- Description:
- The Vela complex is a region of the sky that gathers several stellar and interstellar structures in a few hundred square degrees. Gaia data now allows us to obtain a 3D view of the Vela interstellar structures through the dust extinction. We used the FEDReD (Field Extinction-Distance Relation Deconvolver) algorithm on near-infrared 2MASS data, cross-matched with the Gaia DR2 catalogue, to obtain a 3D cube of extinction density. We applied the FellWalker algorithm on this cube to locate clumps and dense structures. We analysed 18 million stars on 450 deg 2 to obtain the extinction density of the Vela complex from 0.5 to 8kpc at l in [250, 280] and b in [-10, 5].This cube reveals the complete morphology of known structures and relations between them. In particular, we show that the Vela Molecular Ridge is more likely composed by three substructures instead of four, as suggested by the 2D densities. These substructures form the shell of a large cavity. This cavity is visually aligned with the Vela supernova remnant but located at a larger distance. We provide a catalogue of location, distance, size and total dust content of ISM clumps that we extracted.
- ID:
- ivo://CDS.VizieR/J/ApJ/757/51
- Title:
- FIRST-2MASS dust-reddened QSO spectra
- Short Name:
- J/ApJ/757/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 120 dust-reddened quasars identified by matching radio sources detected at 1.4GHz in the Faint Images of the Radio Sky at Twenty Centimeters survey (FIRST) with the near-infrared Two Micron All Sky Survey catalog (2MASS) and color-selecting red sources. Optical and/or near-infrared spectroscopy provide broad wavelength sampling of their spectral energy distributions that we use to determine their reddening, characterized by E(B-V). We demonstrate that the reddening in these quasars is best described by Small-Magellanic-Cloud-like dust. This sample spans a wide range in redshift and reddening (0.1<~z<~3, 0.1<~E(B-V)<~1.5), which we use to investigate the possible correlation of luminosity with reddening. At every redshift, dust-reddened quasars are intrinsically the most luminous quasars. We interpret this result in the context of merger-driven quasar/galaxy co-evolution where these reddened quasars are revealing an emergent phase during which the heavily obscured quasar is shedding its cocoon of dust prior to becoming a "normal" blue quasar. When correcting for extinction, we find that, depending on how the parent population is defined, these red quasars make up <~15%-20% of the luminous quasar population. We estimate, based on the fraction of objects in this phase, that its duration is 15%-20% as long as the unobscured, blue quasar phase.
- ID:
- ivo://CDS.VizieR/J/ApJS/185/32
- Title:
- First-year SDSS-II SN results
- Short Name:
- J/ApJS/185/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04<z<0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. Within the framework of the MLCS2K2 light-curve fitting method, we use the SDSS-II SN sample to infer the mean reddening parameter for host galaxies, R_V_=2.18+/-0.14_stat_+/-0.48_syst_, and find that the intrinsic distribution of host-galaxy extinction is well fitted by an exponential function, P(A_V_)=exp(-A_V_/{tau}_V_), with {tau}_V_=0.334+/-0.088mag. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey (SNLS), the Hubble Space Telescope (HST), and a compilation of Nearby SN Ia measurements. A new feature in our analysis is the use of detailed Monte Carlo simulations of all surveys to account for selection biases, including those from spectroscopic targeting.
