- 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.
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- ID:
- ivo://CDS.VizieR/J/ApJS/208/9
- Title:
- Intrinsic colors and temperatures of PMS stars
- Short Name:
- J/ApJS/208/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the intrinsic colors and temperatures of 5-30 Myr old pre-main-sequence (pre-MS) stars using the F0- through M9-type members of nearby, negligibly reddened groups: the {eta} Cha cluster, the TW Hydra Association, the {beta} Pic Moving Group, and the Tucana-Horologium Association. To check the consistency of spectral types from the literature, we estimate new spectral types for 52 nearby pre-MS stars with spectral types F3 through M4 using optical spectra taken with the SMARTS 1.5 m telescope. Combining these new types with published spectral types and photometry from the literature (Johnson-Cousins BVI_C_, 2MASS JHK_S_ and WISE W1, W2, W3, and W4), we derive a new empirical spectral type-color sequence for 5-30 Myr old pre-MS stars. Colors for pre-MS stars match dwarf colors for some spectral types and colors, but for other spectral types and colors, deviations can exceed 0.3 mag. We estimate effective temperatures (T_eff_) and bolometric corrections (BCs) for our pre-MS star sample through comparing their photometry to synthetic photometry generated using the BT-Settl grid of model atmosphere spectra. We derive a new T_eff_ and BC scale for pre-MS stars, which should be a more appropriate match for T Tauri stars than often-adopted dwarf star scales. While our new T_eff_ scale for pre-MS stars is within =~100K of dwarfs at a given spectral type for stars <G5, for G5 through K6, the pre-MS stars are ~250 K cooler than their MS counterparts. Lastly, we present (1) a modern T_eff_, optical/IR color, and BC sequence for O9V-M9V MS stars based on an extensive literature survey, (2) a revised Q-method relation for dereddening UBV photometry of OB-type stars, and (3) introduce two candidate spectral standard stars as representatives of spectral types K8V and K9V.
- ID:
- ivo://CDS.VizieR/J/MNRAS/407/2475
- Title:
- Ionized gas in E/S0 galaxies with dust lanes
- Short Name:
- J/MNRAS/407/2475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of multicolour observations of 30 E/S0 galaxies with dust lanes. For each galaxy we obtained broad-band images and narrow-band images using interference filters isolating the H{alpha}+[NII] emission lines to derive the amount and morphology of dust and ionized gas. To improve the wavelength coverage we retrieved data from the Sloan Digital Sky Survey and Two Micron All Sky Survey and combined these with our data. Ionized gas is detected in 25 galaxies and shows in most cases a smooth morphology, although knots and filamentary structure are also observed in some objects.
- ID:
- ivo://CDS.VizieR/J/A+A/480/409
- Title:
- IPHAS symbiotic stars candidates
- Short Name:
- J/A+A/480/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of symbiotic stars is essential to understand important aspects of stellar evolution in interacting binaries. Their observed population in the Galaxy is however poorly known, and is one to three orders of magnitudes smaller than the predicted population size. IPHAS, the Isaac Newton Telescope Photometric H{alpha} survey of the Northern Galactic plane, gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume, and discover a significant number of new systems. A method of selecting candidate symbiotic stars by combining IPHAS and near-IR (2MASS) colours is presented. It allows us to distinguish symbiotic binaries from normal stars and most of the other types of H{alpha} emission line stars in the Galaxy. The only exception are T Tauri stars, which can however be recognized because of their concentration in star forming regions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/103
- Title:
- IPHAS T Tauri candidates in IC 1396
- Short Name:
- J/MNRAS/415/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Isaac Newton Telescope (INT) Photometric H-Alpha Survey (IPHAS) is a 1800deg^2^ survey of the Northern Galactic Plane, reaching down to r'~21. We demonstrate how the survey can be used to (1) reliably select classical T Tauri star candidates and (2) constrain the mass accretion rates with an estimated relative uncertainty of 0.6dex. IPHAS is a necessary addition to spectroscopic surveys because it allows large and uniform samples of accretion rates to be obtained with a precise handle on the selection effects. We apply the method on a region of 7deg^2^ towards the HII region IC 1396 in Cepheus OB2 and identify 158 pre-main-sequence candidates with masses between 0.2 and 2.0M_{sun}_ and accretion rates between 10-9.2 and 10-7.0M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/659/599
- Title:
- IRAC and JHKs photometry of h and chi Persei
- Short Name:
- J/ApJ/659/599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe IRAC 3.6-8um observations and ground-based near-IR JHKs photometry from Mimir and 2MASS of the massive double cluster h and chi Persei complete to J=15.5 (M~1.3M_{sun}_). Within 25' of the cluster centers we detect ~11000 sources with J<=15.5, ~7000 sources with [4.5]<=15, and ~5000 sources with [8]<=14.5. In both clusters the surface density profiles derived from the 2MASS data decline with distance from the cluster centers as expected for a bound cluster. Within 15' of the cluster centers, ~50% of the stars lie on a reddened ~13Myr isochrone; at 15'-25' from the cluster centers, ~40% lie on this isochrone. Thus, the optical/2MASS color-magnitude diagrams indicate that h and chi Per are accompanied by a halo population with roughly the same age and distance as the two dense clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2159
- Title:
- IRAC counterparts of 6cm galaxies in EGS
- Short Name:
- J/AJ/132/2159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new 6cm survey of almost 0.6deg^2^ to a limit of 0.55mJy/beam (10sigma) finds 37 isolated radio sources and seven radio-source pairs (not necessarily physical companions). Infrared Array Camera (IRAC) counterparts are identified for at least 92% of the radio sources within the area of deep IRAC coverage, which includes 31 isolated sources and six pairs. This contrasts with an identification rate of <74% to R<23.95 in visible light. Eight of the IRAC galaxies have power-law spectral energy distributions, implying that the mid-infrared emission comes from a powerful active galactic nucleus (AGN). The remaining 26 IRAC galaxies show stellar emission in the mid-infrared, probably in most of these galaxies because the stellar emission is bright enough to outshine an underlying AGN.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/4259
- Title:
- IRAC Dark Field, ELAIS-N1 and ADF-S galaxies
- Short Name:
- J/MNRAS/472/4259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimised data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the Spitzer space telescope via its comprehensive coverage between 8-24{mu}m filling the gap between the Spitzer IRAC and MIPS instruments.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/72
- Title:
- IRAC identifications for 510 AEGIS20 radio sources
- Short Name:
- J/ApJ/756/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Infrared 3.6-8{mu}m images of the Extended Groth Strip yield plausible counterpart identifications for all but one of 510 radio sources in the AEGIS20 S(1.4GHz)>50{mu}Jy sample. This is the first such deep sample that has been effectively 100% identified. Achieving the same identification rate at R band would require observations reaching R_AB_>27. Spectroscopic redshifts are available for 46% of the sample and photometric redshifts for an additional 47%. Almost all of the sources with 3.6{mu}m AB magnitudes brighter than 19 have spectroscopic redshifts z<1.1, while fainter objects predominantly have photometric redshifts with 1<~z<~3. Unlike more powerful radio sources that are hosted by galaxies having large stellar masses within a relatively narrow range, the AEGIS20 counterparts have stellar masses spanning more than a factor of 10 at z~1. The sources are roughly 10%-15% starbursts at z<~0.5 and 20%-25% active galactic nuclei mostly at z>1 with the remainder of uncertain nature.
- ID:
- ivo://CDS.VizieR/J/ApJ/675/1375
- Title:
- IRAC/MIPS photometry in Cha I
- Short Name:
- J/ApJ/675/1375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a census of circumstellar disks in the Chamaeleon I star-forming region. Using the Infrared Array Camera and the Multiband Imaging Photometer on board the Spitzer Space Telescope, we have obtained images of Chamaeleon I at 3.6, 4.5, 5.8, 8.0, and 24um. To search for new disk-bearing members of the cluster, we have performed spectroscopy on objects that have red colors in these data. Through this work, we have discovered four new members of Chamaeleon I with spectral types of M4, M6, M7.5, and L0.
