- 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.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/BaltA/17/125
- Title:
- Interstellar reddening in 3 HII regions
- Short Name:
- J/BaltA/17/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The slope of the interstellar reddening line in the J-H vs. H-Ks diagram of the 2MASS survey in the direction of the North America and Pelican nebulae, the L 935 dust cloud and the Cyg OB2 association is determined. The MK types were either classified by C.J. Corbally or collected from the literature. The ratio E(J-H)/E(H-Ks)=2.0 is obtained by taking the average for the four groups of spectral classes: O3-B1, B2-B6, B7-B9.5 and red clump giants. The obtained ratio is among the largest values of E(J-H)/E(H-Ks) determined till now.
- 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/MNRAS/435/1300
- Title:
- Intranight optical variability of AGN
- Short Name:
- J/MNRAS/435/1300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The incidence of intranight optical variability (INOV) is known to differ significantly among different classes of powerful active galactic nuclei (AGN). A number of statistical methods have been employed in the literature for testing the presence of INOV in the light curves, sometimes leading to discordant results. In this paper, we compare the INOV characteristics of six prominent classes of AGN, as evaluated using three commonly used statistical tests, namely the {chi}^2^-test, the modified C-test and the F-test, which has recently begun to gain popularity. The AGN classes considered are: radio-quiet quasars, radio-intermediate quasars, lobe-dominated quasars, low optical polarization core-dominated quasars, high optical polarization core-dominated quasars and TeV blazars. Our analysis is based on a large body of AGN monitoring data, involving 262 sessions of intranight monitoring of a total 77 AGN, using 1-2m class optical telescopes located in India. In order to compare the usefulness of the statistical tests, we have also subjected them to a 'sanity check' by comparing the number of false positives yielded by each test with the corresponding statistical prediction. The present analysis is intended to serve as a benchmark for future INOV studies of AGN of different classes.
- 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/ApJ/731/120
- Title:
- Intrinsic SN Ia light curves
- Short Name:
- J/ApJ/731/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a comprehensive statistical model for Type Ia supernova (SN Ia) light curves spanning optical through near-infrared (NIR) data. A hierarchical framework coherently models multiple random and uncertain effects, including intrinsic supernova (SN) light curve covariances, dust extinction and reddening, and distances. An improved BayeSN Markov Chain Monte Carlo code computes probabilistic inferences for the hierarchical model by sampling the global probability density of parameters describing individual SNe and the population. We have applied this hierarchical model to optical and NIR data of 127 SNe Ia from PAIRITEL, CfA3, Carnegie Supernova Project, and the literature. We find an apparent population correlation between the host galaxy extinction AV and the ratio of total-to-selective dust absorption RV. For SNe with low dust extinction, A_V_<~0.4, we find R_V_~2.5-2.9, while at high extinctions, A_V_>~1, low values of R_V_<2 are favored. The NIR luminosities are excellent standard candles and are less sensitive to dust extinction. They exhibit low correlation with optical peak luminosities, and thus provide independent information on distances. The combination of NIR and optical data constrains the dust extinction and improves the predictive precision of individual SN Ia distances by about 60%. Using cross-validation, we estimate an rms distance modulus prediction error of 0.11mag for SNe with optical and NIR data versus 0.15mag for SNe with optical data alone. Continued study of SNe Ia in the NIR is important for improving their utility as precise and accurate cosmological distance indicators.
- 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/590/A67
- Title:
- Ionized gas maps of local U/LIRGs
- Short Name:
- J/A+A/590/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 2D study of star formation at kpc and sub-kpc scales of a sample of local (z<0.1) U/LIRGs, based on near-IR VLT-SINFONI observations. We obtained integrated measurements of the star formation rate (SFR) and star formation rate surface density, together with their 2D distributions, based on Br_gamma and Pa_alpha emission. We observe a tight linear correlation between the SFR derived from our extinction-corrected measurements and that derived from 24 micron data, and a reasonable agreement with SFR derived from total IR luminosity. Our near-IR measurements are on average a factor 3 larger than optical SFR, even when extinction corrections are applied. We found that LIRGs have a median-observed star formation rate surface density of 1.72M_{sun}_/yr/kpc^2^ for the extinction-corrected distribution, whilst ULIRGs have 0.23M_{sun}_/yr/kpc^2, respectively. These median values for ULIRGs increase up to 2.90M_{sun}_/yr/kpc^2^, when only their inner regions, covering the same size as the average FoV of LIRGs, are considered. We identified a total of 95 individual SF clumps in our sample, with sizes within 60-1500pc, and extinction-corrected Pa_alpha luminosities of 10^5^-10^8^L_{sun}_. Star-forming clumps in LIRGs are about ten times larger and thousands of times more luminous than typical clumps in spiral galaxies. Clumps in ULIRGs have sizes similar (x0.5-1) to those of high-z clumps, having Pa_alpha luminosities similar to some high-z clumps, and about 10 times less luminous than the most luminous high-z clumps identified so far. We also observed a change in the slope of the L-r relation. A likely explanation is that most luminous galaxies are interacting and merging, and therefore their size represents a combination of the distribution of the star-forming clumps within each galaxy in the system plus the effect of the projected distance.
- ID:
- ivo://CDS.VizieR/II/321
- Title:
- IPHAS DR2 Source Catalogue
- Short Name:
- II/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The INT/WFC Photometric H-Alpha Survey of the Northern Galactic Plane (IPHAS) is a 1860 deg^2^ imaging survey of the Northern Milky Way at red visible wavelengths. It covers Galactic latitudes |b|<5{deg} and longitudes l=30 to 215{deg} in the broad-band r, i and narrow-band H-alpha filters using the Wide Field Camera (WFC) on the 2.5-m Isaac Newton Telescope (INT) in La Palma. IPHAS Data Release 2 (DR2) is the first quality-controlled and globally calibrated source catalogue derived from the survey, providing single-epoch photometry for 219 million unique sources across 92% of the footprint. The observations were carried out between 2003 and 2012 at a median seeing of 1.1 arcsec (sampled at 0.33 arcsec/pixel) and to a mean 5-sigma depth of 21.2 (r), 20.0 (i) and 20.3 (H-alpha). The photometric calibration is in the Vega magnitude system and carries an external precision of 0.03mag (root-mean-square error). The catalogue includes all the sources which have been detected at a signal-to-noise ratio of 5 or better in at least one band. Many applications will require a combination of quality criteria to be applied to avoid faint stars or confused sources. The choice of quality criteria tensions completeness against reliability, and hence depends on the requirements of a project. To aid users, the data release paper (arXiv:1406.4862) recommends two sets of quality criteria, named "a10" and "a10point", which should satisfy most projects. As a minimum, the "a10" criteria select objects which have been detected at the minimum level of 10-sigma in all bands, without being saturated. Additional constraints are provided by the "a10point" criteria, which require objects to be point sources free of blending, unaffected by nearby bright stars, as well as being unsaturated >10-sigma detections in all bands. Sources in both categories are flagged in the catalogue using the boolean columns a10 and a10point. Imaging and auxiliary data are available from the project website (www.iphas.org).
- 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.
