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- ID:
- ivo://CDS.VizieR/J/AJ/158/22
- Title:
- A new IR study of intrinsic and extrinsic S-type stars
- Short Name:
- J/AJ/158/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We collect all known intrinsic and extrinsic S-type stars to discuss their infrared properties and find their difference in the infrared using photometric data from the Two Micron All Sky Survey, Wide Field Infrared Survey Explorer, and Infrared Astronomical Satellite missions. Then we look for the diagnosis to extract intrinsic S-type stars from the large unclassified sample. We found that, statistically, intrinsic S-type stars have larger infrared excesses than extrinsic S-type stars in the wavelength region of 1-60 {mu}m due to thicker dusty circumstellar envelopes. We also found that only intrinsic S-type stars occupy the reddest color areas in all of the two-color diagrams we presented. Finally, 172 new intrinsic S-type stars are presented in this paper. This makes the number of known intrinsic S-type stars almost double. In addition, some intrinsic and extrinsic S-type stars have power-law distributions in some two-color diagrams with the wavelength longer than 5 {mu}m. The possible reason for this is also discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/154/269
- Title:
- A new photo-z method for quasars in Stripe 82
- Short Name:
- J/AJ/154/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new algorithm to estimate quasar photometric redshifts (photo-zs), by considering the asymmetries in the relative flux distributions of quasars. The relative flux models are built with multivariate Skew-t distributions in the multidimensional space of relative fluxes as a function of redshift and magnitude. For 151392 quasars in the SDSS, we achieve a photo-z accuracy, defined as the fraction of quasars with the difference between the photo-z z_p_ and the spectroscopic redshift z_s_, |{Delta}_z_|=|z_s_-z_p_|/(1+z_s_) within 0.1, of 74%. Combining the WISE W1 and W2 infrared data with the SDSS data, the photo-z accuracy is enhanced to 87%. Using the Pan-STARRS1 or DECaLS photometry with WISE W1 and W2 data, the photo-z accuracies are 79% and 72%, respectively. The prior probabilities as a function of magnitude for quasars, stars, and galaxies are calculated, respectively, based on (1) the quasar luminosity function, (2) the Milky Way synthetic simulation with the Besancon model, and (3) the Bayesian Galaxy Photometric Redshift estimation. The relative fluxes of stars are obtained with the Padova isochrones, and the relative fluxes of galaxies are modeled through galaxy templates. We test our classification method to select quasars using the DECaLS g, r, z, and WISE W1 and W2 photometry. The quasar selection completeness is higher than 70% for a wide redshift range 0.5<z<4.5, and a wide magnitude range 18<r<21.5 mag. Our photo-z regression and classification method has the potential to extend to future surveys. The photo-z code will be publicly available.
- ID:
- ivo://CDS.VizieR/J/ApJ/827/118
- Title:
- A new reverberation mapping campaign on NGC 5548
- Short Name:
- J/ApJ/827/118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 5548 is the best-observed reverberation-mapped active galactic nucleus with long-term, intensive monitoring. Here we report results from a new observational campaign between 2015 January and July. We measure the centroid time lag of the broad H{beta} emission line with respect to the 5100{AA} continuum and obtain {tau}_cent_=7.20_-0.35_^+1.33^days in the rest frame. This yields a black hole mass of M.=8.71_-2.61_^+3.21^x10^7^M_{sun}_ using a broad H{beta} line dispersion of 3124+/-302km/s and a virial factor of f_BLR_=6.3+/-1.5 for the broad-line region (BLR), consistent with the mass measurements from previous H{beta} campaigns. The high-quality data allow us to construct a velocity-binned delay map for the broad H{beta} line, which shows a symmetric response pattern around the line center, a plausible kinematic signature of virialized motion of the BLR. Combining all the available measurements of H{beta} time lags and the associated mean 5100{AA} luminosities over 18 campaigns between 1989 and 2015, we find that the H{beta} BLR size varies with the mean optical luminosity, but, interestingly, with a possible delay of 2.35_-1.25_^+3.47^ years. This delay coincides with the typical BLR dynamical timescale of NGC 5548, indicating that the BLR undergoes dynamical changes, possibly driven by radiation pressure.
- ID:
- ivo://CDS.VizieR/J/A+A/611/A74
- Title:
- Angular differential imaging of MCW 758
- Short Name:
- J/A+A/611/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transition disks offer the extraordinary opportunity to look for newly born planets and investigate the early stages of planet formation. In this context we observed the Herbig A5 star MWC 758 with the L'-band vector vortex coronagraph installed in the near infrared camera and spectrograph NIRC2 at the Keck II telescope, with the aim of unveiling the nature of the spiral structure by constraining the presence of planetary companions in the system. Our high-contrast imaging observations show a bright ({Delta}L'=7.0+/-0.3mag) point-like emission, south of MWC 758 at a deprojected separation of ~20au (r=0.111"+/-0.004") from the central star. We also recover the two spiral arms (south-east and north-west), already imaged by previous studies in polarized light, and discover a third one to the south-west of the star. No additional companions were detected in the system down to 5 Jupiter masses beyond 0.6" from the star. We propose that the bright L' band emission could be caused by the presence of an embedded and accreting protoplanet, although the possibility of it being an asymmetric disk feature cannot be excluded. The spiral structure is probably not related to the protoplanet candidate, unless on an inclined and eccentric orbit, and it could be due to one (or more) yet undetected planetary companions at the edge of or outside the spiral pattern. Future observations and additional simulations will be needed to shed light on the true nature of the point-like source and its link with the spiral arms.
226. AN Lyn light maxima
- ID:
- ivo://CDS.VizieR/J/A+A/328/235
- Title:
- AN Lyn light maxima
- Short Name:
- J/A+A/328/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New uvby data collected of AN Lyn together with the reanalysis of old data establish that this star is a multiperiodic pulsator. Three independent frequencies ({nu}_1_=10.1756, {nu}_2_=18.1309 and {nu}_3_=9.5598c/d) and some interactions between them are found to be present in the light curve. Changes in amplitude with a large time scale are confirmed for the main frequency. Moreover, changes in amplitude are also present for the secondary frequencies, especially for {nu}_3_. After subtraction of the secondary frequencies from the light curves, the classical O-C method has been used to analyse the behaviour of the main period. A comparison is made between AN Lyn and the other two known {delta} Sct stars with atypical light curves, i.e., V1719 Cyg and V798 Cyg. New uvby data have been also collected for V1719 Cyg and the O-C method has been used to analyse the behaviour of the main period. It is found that the main pulsation of this star can be well described by means of a linear ephemeris with a period of P=0.26729700d over the last eighteen years. Finally, analysis of the different data sets available in the literature do not reveal significative changes in the amplitude of the main frequency of V1719 Cyg.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/3883
- Title:
- A non-parametric method for galaxy morphology
- Short Name:
- J/MNRAS/437/3883
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a non-parametric cell-based method of selecting highly pure and largely complete samples of spiral galaxies using photometric and structural parameters as provided by standard photometric pipelines and simple shape fitting algorithms. The performance of the method is quantified for different parameter combinations, using purely human-based classifications as a benchmark. The discretization of the parameter space allows a markedly superior selection than commonly used proxies relying on a fixed curve or surface of separation. Moreover, we find structural parameters derived using passbands longwards of the g band and linked to older stellar populations, especially the stellar mass surface density mu_*_ and the r band effective radius r_e_, to perform at least equally well as parameters more traditionally linked to the identification of spirals by means of their young stellar populations, e.g. UV/optical colours. In particular the distinct bimodality in the parameter mu_*_, consistent with expectations of different evolutionary paths for spirals and ellipticals, represents an often overlooked yet powerful parameter in differentiating between spiral and non-spiral/elliptical galaxies. We use the cell-based method for the optical parameter set including r_e_ in combination with the Sersic index n and the i-band magnitude to investigate the intrinsic specific star-formation rate - stellar mass relation ({psi}_*_-M_*_) for a morphologically defined volume limited sample of local universe spiral galaxies. The relation is found to be well described by {psi}_*_{propto}M_*_^-0.5^ over the range of 10^9.5^M_{sun}_<=M_*_<=10^11^M_{sun}_ with a mean interquartile range of 0.4dex. This is somewhat steeper than previous determinations based on colour-selected samples of star-forming galaxies, primarily due to the inclusion in the sample of red quiescent disks.
- ID:
- ivo://CDS.VizieR/II/97
- Title:
- ANS UV Catalogue of Point Sources
- Short Name:
- II/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is a result of the observations made with the Astronomical Netherlands Satellite (ANS) which operated between October 1974 and April 1976. The ANS satellite observed in five UV channels centered around 150, 180, 220, 250 and 330nm. The photometric bands are: -------------------------------------------------------------------------- Band designation 15N 15W 18 22 25 33 -------------------------------------------------------------------------- Central wavelength (nm) 154.5 154.9 179.9 220.0 249.3 329.4 Bandwidth (nm) 5.0 14.9 14.9 20.0 15.0 10.1 -------------------------------------------------------------------------- The reported magnitudes were obtained from mean count rates converted to fluxes using the ANS absolute calibration of Wesselius et al. (1980A&A....85..221W). In addition to the ultraviolet magnitudes, the catalog contains positions taken from the satellite pointing, spectral types, and UBV data from other sources as well as comments on duplicity, variability, and miscellaneous notes concerning individual objects.
- ID:
- ivo://CDS.VizieR/J/AZh/84/695
- Title:
- An SX Phoenicis Variable light curve
- Short Name:
- J/AZh/84/695
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present investigation of V=17mag star, which appears to be SX Phe type variable. Observations at 1.8 and 1.0 meter telescopes of Boyhunsan and Mount Lemon observatories permit us to improve the light elements and to investigate the power spectrum. We applied a Fourier decomposition to the data in order to determine the component frequencies of the synthetic light curve, and five components including a pair of closely separated components of f_1_=24.6539 and f_2_=24.8173 c/d were identified. We proposed that one of these two components corresponds to a non-radial oscillation mode. Other observed frequencies are the combinations of the first two. Metallicity of the star was estimated to be [Fe/H]<-2. We also found that one of the faint variable stars, No. 14, in the field is RRc type pulsator.
- ID:
- ivo://CDS.VizieR/J/AJ/140/75
- Title:
- Antennae galaxies (NGC 4038/4039) revisited
- Short Name:
- J/AJ/140/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Advanced Camera for Surveys and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) have been used to obtain new Hubble Space Telescope images of NGC 4038/4039 ("The Antennae"). These new observations allow us to better differentiate compact star clusters from individual stars, based on both size and color.
