- ID:
- ivo://CDS.VizieR/J/ApJ/884/11
- Title:
- Exploring 6 AGN dusty torus models. II.
- Short Name:
- J/ApJ/884/11
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers devoted to exploring a set of six dusty models of active galactic nuclei (AGN) with available spectral energy distributions. These models are the smooth torus by Fritz+ (2006MNRAS.366..767F), the clumpy torus by Nenkova+ (2008ApJ...685..147N and 2008ApJ...685..160N), the clumpy torus by Honig & Kishimoto (2010A&A...523A..27H), the two-phase torus by Siebenmorgen+ (2015A&A...583A.120S), the two-phase torus by Stalevski+ (2012MNRAS.420.2756S and 2016MNRAS.458.2288S), and the wind model by Honig & Kishimoto (2017ApJ...838L..20H). The first paper explores discrimination among models and the parameter restriction using synthetic spectra. Here we perform spectral fitting of a sample of 110 AGN drawn from the Swift/BAT survey with Spitzer/IRS spectroscopic data. The aim is to explore which is the model that describes better the data and the resulting parameters. The clumpy wind-disk model by Honig & Kishimoto provides good fits for ~50% of the sample, and the clumpy torus model by Nenkova+ is good at describing ~30% of the objects. The wind-disk model by Honig & Kishimoto is better for reproducing the mid-infrared spectra of type 1 Seyferts (with 60% of the type 1 Seyferts well reproduced by this model compared to the 10% well represented by the clumpy torus model by Nenkova+), while type 2 Seyferts are equally fitted by both models (roughly 40% of the type 2 Seyferts). Large residuals are found irrespective of the model used, indicating that the AGN dust continuum emission is more complex than predicted by the models or that the parameter space is not well sampled. We found that all the resulting parameters for our AGN sample are roughly constrained to 10%-20% of the parameter space. Contrary to what is generally assumed, the derived outer radius of the torus is smaller (reaching up to a factor of ~5 smaller for 10pc tori) for the smooth torus by Fritz+ and the two-phase torus by Stalevski+ than the one derived from the clumpy torus by Nenkova+ Covering factors and line-of-sight viewing angles strongly depend on the model used. The total dust mass is the most robust derived quantity, giving equivalent results for four of these models.
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- ID:
- ivo://CDS.VizieR/J/BaltA/11/231
- Title:
- Extinction in MBM12
- Short Name:
- J/BaltA/11/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric magnitudes and color indices in the Vilnius seven-color system for 152 stars are used to investigate the interstellar extinction in the area of the Aries molecular cloud MBM 12, coinciding with the L1454 and L1457 dust clouds. Spectral types, absolute magnitudes, color excesses, interstellar extinctions and distances of the stars are determined. The plot of interstellar extinction A_v_ versus distance shows that the dust cloud is situated at a distance of 325pc, at 180pc from the Galactic plane, and its true diameter is about 11pc. The interstellar extinction law in the area is found to be normal, typical for the diffuse dust. Ten peculiar or unresolved binary stars and some heavily reddened stars are detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/L81
- Title:
- Extinction in star-forming regions
- Short Name:
- J/ApJ/693/L81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Spitzer Infrared Spectrograph observations of G0-M4III stars behind dark clouds, I construct 5-20um empirical extinction curves for 0.3<=A_K_<7, which is equivalent to A_V_ between ~3 and 50. For A_K_<1, the curve appears similar to the Mathis diffuse interstellar medium extinction curve, but with a greater degree of extinction. For A_K_>1, the curve exhibits lower contrast between the silicate and absorption continuum, develops ice absorption, and lies closer to the Weingartner and Draine R_V_=5.5 Case B curve, a result which is consistent with that of Flaherty et al. (2007ApJ...663.1069F) and Chiar et al. (2007ApJ...666L..73C). Recently, work using Spitzer Infrared Array Camera data by Chapman et al. independently reaches a similar conclusion that the shape of the extinction curve changes as a function of increasing A_K_. By calculating the optical depths of the 9.7um silicate and 6.0, 6.8, and 15.2um ice features, I determine that a process involving ice is responsible for the changing shape of the extinction curve and speculate that this process is a coagulation of ice-mantled grains rather than ice-mantled grains alone.
- 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).
- 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/573/A21
- Title:
- Extinction of Titan haze at 3 micron
- Short Name:
- J/A+A/573/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The chemical nature of the Titan haze is poorly understood. The investigation carried out by the Cassini-Huygens suite of instruments is bringing new insights into this question. This work aims at deriving the vertical variation of the spectral structure of the 3.3-3.4um absorption feature of the Titan haze from Cassini VIMS solar occultation data recorded between 250 and 700km altitude.
- 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).
