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15991. Type-II and anomalous Cepheids in LMC
ID:
ivo://CDS.VizieR/J/AcA/58/293
Title:
Type-II and anomalous Cepheids in LMC
Short Name:
J/AcA/58/293
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the second part of the OGLE-III Catalog of Variable Stars (OIII-CVS) we present 197 type II Cepheids and 83 anomalous Cepheids in the Large Magellanic Cloud (LMC). The sample of type II Cepheids consists of 64 BL Her stars, 96 W Vir stars and 37 RV Tau stars. Anomalous Cepheids are divided into 62 fundamental-mode and 21 first-overtone pulsators. These are the largest samples of such types of variable stars detected anywhere outside the Galaxy.
15992. Type II and anomalous Cepheids luminosities
ID:
ivo://CDS.VizieR/J/A+A/603/A70
Title:
Type II and anomalous Cepheids luminosities
Short Name:
J/A+A/603/A70
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type II and anomalous Cepheids (ACs) are useful distance indicators when there are too few classical Cepheids or when RR Lyrae stars are too faint. Type II and ACs follow a period-luminosity relation as well, but they are less well-studied classes of objects. In this paper we study the sample of 335 Type II and ACs in the Small and Large Magellanic Clouds detected in OGLE-III data. The spectral energy distributions (SEDs) are constructed from photometric data available in the literature and fitted with a dust radiative transfer model, thereby leading to a determination of luminosity and effective temperature. In addition, a subsample of targets is investigated for possible binarity by looking for the light-time travel effect (LITE). Hertzsprung-Russell diagrams (HRD) are constructed and compared to evolutionary tracks and theoretical instability strips (ISs). In agreement with previous suggestions, the BL Her subclass can be explained by the evolution of ~0.5-0.6M_{sun}_ stars evolving off the zero-age horizontal branch and the ACs can be explained by the evolution of ~1.1-2.3M_{sun}_ stars. The evolution of the W Vir subclass is not clear. These objects are at higher luminosities than ACs and evolutionary tracks of ~2.5-4M_{sun}_ stars cross this region in the HRD, but the periods of the W Vir are longer than those of the short period classical Cepheids at these luminosities, which indicates the former have lower masses. A low-mass star experiencing a thermal pulse when the envelope mass is small can make a blue loop into the IS region of the W Vir stars. But the timescale is extremely short, so this is also no explanation for the W Vir as a class. A relation to binarity might be at the origin of the W Vir stars, which has already been explicitly suggested for the peculiar W Vir stars. For ~60% of the RV Tau and ~10% of the W Vir objects an infrared excess is detected from the SED fitting. A recent result is confirmed that stars exist with luminosities below that predicted from single-star evolution, which show a clear infrared excess, and the shape of the excess suggests a connection to binary evolution. The investigation of the LITE effect revealed 20 systems that appear to show periodic variations and may be new binaries, although this study requires follow-up. About 40 stars show significant period changes.
15993. Type II Cepheid and RR Lyrae variables
ID:
ivo://CDS.VizieR/J/MNRAS/386/2115
Title:
Type II Cepheid and RR Lyrae variables
Short Name:
J/MNRAS/386/2115
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared and optical absolute magnitudes are derived for the type II Cepheids kappa Pav and VY Pyx using revised Hipparcos parallaxes and for kappa Pav, V553 Cen and SW Tau from pulsational parallaxes. Revised Hipparcos and HST parallaxes for RR Lyrae agree satisfactorily and are combined in deriving absolute magnitudes. Phase-corrected J, H and Ks mags are given for 142 Hipparcos RR Lyraes based on Two-Micron All-Sky Survey observations. Pulsation and trigonometrical parallaxes for classical Cepheids are compared to establish the best value for the projection factor (p) used in pulsational analyses.
15994. Type II Cepheid candidates. IV. Objects from NSVS
ID:
ivo://CDS.VizieR/J/AJ/146/61
Title:
Type II Cepheid candidates. IV. Objects from NSVS
Short Name:
J/AJ/146/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained VR photometry of 447 Cepheid variable star candidates with declinations north of -14{deg}30', most of which were identified using the Northern Sky Variability Survey (NSVS) data archive. Periods and other photometric properties were derived from the combination of our data with the NSVS data. Atmospheric parameters were determined for 81 of these stars from low-resolution spectra. The identification of type II Cepheids based on the data presented in all four papers in this series is discussed. On the basis of spectra, 30 type II Cepheids were identified while 53 variables were identified as cool, main sequence stars and 283 as red giants following the definitions in Paper III. An additional 30 type II Cepheids were identified on the basis of light curves. The present classifications are compared with those from the Machine-learned All Sky Automated Survey Classification Catalog for 174 stars in common.
15995. Type II Cepheids abundances
ID:
ivo://CDS.VizieR/J/MNRAS/477/2276
Title:
Type II Cepheids abundances
Short Name:
J/MNRAS/477/2276
Date:
21 Oct 2021
Publisher:
CDS
Description:
The chemical composition of 28 Population II Cepheids and one RR Lyrae variable has been studied using high-resolution spectra. The chemical composition of W Vir variable stars (with periods longer than 8 d) is typical for the halo and thick disc stars. However, the chemical composition of BL Her variables (with periods of 0.8-4 d) is drastically different, although it does not differ essentially from that of the stars belonging to globular clusters. In particular, the sodium overabundance ([Na/Fe]~=0.4) is reported for most of these stars, and the Na-O anticorrelation is also possible. The evolutionary tracks for BL Her variables (with a progenitor mass value of 0.8 solar masses) indicate that mostly helium-overabundant stars (Y=0.30-0.35) can fall into the instability strip region. We suppose that it is the helium overabundance that accounts not only for the existence of BL Her variable stars but also for the observed abnormalities in the chemical composition of this small group of pulsating variables.
15996. Type II Cepheids in the Galactic bulge
ID:
ivo://CDS.VizieR/J/A+A/619/A51
Title:
Type II Cepheids in the Galactic bulge
Short Name:
J/A+A/619/A51
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new Near-Infrared photometry of Type II Cepheids in the Bulge from the VISTA Variables in the Via Lactea survey (VVV) (Minniti et al., 2010NewA...15..433M; Saito et al., 2012A&A...537A.107S, Cat. II/337. We provide the largest sample (894 stars) of T2Cs with JHKs observations that have accurate periods from the OGLE catalog (Soszynski et al., 2017, Cat. J/AcA/67/297). Our analysis makes use of the Ks-band time-series observations to estimate mean-magnitudes and individual distances by means of the Period-Luminosity PL relation. To constrain the kinematic properties of our targets, we complement our analysis with proper motions based on both the VVV and Gaia Data Release 2.
15997. Type IIn supernova photometry
ID:
ivo://CDS.VizieR/J/A+A/637/A73
Title:
Type IIn supernova photometry
Short Name:
J/A+A/637/A73
Date:
14 Jan 2022 08:08:51
Publisher:
CDS
Description:
The evolution of a Type IIn supernova (SN IIn) is governed by the interaction between the SN ejecta and a hydrogen-rich circumstellar medium (CSM). SNe IIn thus allow us to probe the late-time mass-loss history of their progenitor stars. We present optical photometry of a sample of 42 Type IIn supernovae, obtained by the Palomar Transient Factory (PTF) collaboration and its successor, the intermediate PTF (iPTF), from 2009 to 2017 using the 1.2m Samuel Oschin telescope and the 1.52m telescope at Palomar Observatory, California, USA.
15998. 26 type II-Plateau supernovae parameters
ID:
ivo://CDS.VizieR/J/ApJ/799/215
Title:
26 type II-Plateau supernovae parameters
Short Name:
J/ApJ/799/215
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of Type II-Plateau supernovae based on their expansion velocities and photometric measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and velocities. We simultaneously fit ~230 velocity and ~6800mag measurements distributed over 21 photometric passbands spanning wavelengths from 0.19 to 2.2{mu}m. The light-curve differences among the Type II-Plateau supernovae are well modeled by assuming different rates of photospheric radius expansion, which we explain as different density profiles of the ejecta, and we argue that steeper density profiles result in flatter plateaus, if everything else remains unchanged. The steep luminosity decline of Type II-Linear supernovae is due to fast evolution of the photospheric temperature, which we verify with a successful fit of SN 1980K. Eliminating the need for theoretical supernova atmosphere models, we obtain self-consistent relative distances, reddenings, and nickel masses fully accounting for all internal model uncertainties and covariances. We use our global fit to estimate the time evolution of any missing band tailored specifically for each supernova, and we construct spectral energy distributions and bolometric light curves. We produce bolometric corrections for all filter combinations in our sample. We compare our model to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard R~3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.
15999. Type II-P SN progenitor constraints
ID:
ivo://CDS.VizieR/J/MNRAS/395/1409
Title:
Type II-P SN progenitor constraints
Short Name:
J/MNRAS/395/1409
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a 10.5-yr, volume-limited (28-Mpc) search for supernova (SN) progenitor stars. In doing so we compile all SNe discovered within this volume (132, of which 27 per cent are Type Ia) and determine the relative rates of each subtype from literature studies. The core-collapse SNe break down into 59 per cent II-P and 29 per cent Ib/c, with the remainder being IIb (5 per cent), IIn (4 per cent) and II-L (3 per cent). There have been 20 II-P SNe with high-quality optical or near-infrared pre-explosion images that allow a meaningful search for the progenitor stars. In five cases they are clearly red supergiants, one case is unconstrained, two fall on compact coeval star clusters and the other twelve have no progenitor detected. We review and update all the available data for the host galaxies and SN environments (distance, metallicity and extinction) and determine masses and upper mass estimates for these 20 progenitor stars using the stars stellar evolutionary code and a single consistent homogeneous method. A maximum likelihood calculation suggests that the minimum stellar mass for a Type II-P to form is m_min_= 8.5^+1^_-1.5_M_{sun}_ and the maximum mass for II-P progenitors is m_max_= 16.5+/-1.5M_{sun}_, assuming a Salpeter initial mass function holds for the progenitor population (in the range {Gamma}=-1.35^+0.3^_-0.7_). The minimum mass is consistent with current estimates for the upper limit to white dwarf progenitor masses, but the maximum mass does not appear consistent with massive star populations in Local Group galaxies. Red supergiants in the Local Group have masses up to 25M_{sun}_ and the minimum mass to produce a Wolf-Rayet star in single star evolution (between solar and LMC metallicity) is similarly 25-30M_{sun}_. The reason we have not detected any high-mass red supergiant progenitors above 17M_{sun}_ is unclear, but we estimate that it is statistically significant at 2.4{sigma} confidence. Two simple reasons for this could be that we have systematically underestimated the progenitor masses due to dust extinction or that stars between 17-25M_{sun}_produce other kinds of SNe which are not II-P. We discuss these possibilities and find that neither provides a satisfactory solution. We term this discrepancy the 'red supergiant problem' and speculate that these stars could have core masses high enough to form black holes and SNe which are too faint to have been detected. We compare the ^56^Ni masses ejected in the SNe to the progenitor mass estimates and find that low-luminosity SNe with low ^56^Ni production are most likely to arise from explosions of low-mass progenitors near the mass threshold that can produce a core-collapse.
16000. Type IIP supernovae from Pan-STARRS1
ID:
ivo://CDS.VizieR/J/ApJ/799/208
Title:
Type IIP supernovae from Pan-STARRS1
Short Name:
J/ApJ/799/208
Date:
21 Oct 2021
Publisher:
CDS
Description:
In recent years, wide-field sky surveys providing deep multiband imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SNe): systematic light-curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1, obtained over a constant survey program of 4yr and classified using both spectroscopy and machine-learning-based photometric techniques. We develop and apply a new Bayesian model for the full multiband evolution of each light curve in the sample. We find no evidence of a subpopulation of fast-declining explosions (historically referred to as "Type IIL" SNe). However, we identify a highly significant relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single parameter, likely determined by initial stellar mass, predominantly controlling the explosions of red supergiants. This relation could also be applied for SN cosmology, offering a standardizable candle good to an intrinsic scatter of <~0.2mag. We compare each light curve to physical models from hydrodynamic simulations to estimate progenitor initial masses and other properties of the Pan-STARRS1 Type IIP SN sample. We show that correction of systematic discrepancies between modeled and observed SN IIP light-curve properties and an expanded grid of progenitor properties are needed to enable robust progenitor inferences from multiband light-curve samples of this kind. This work will serve as a pathfinder for photometric studies of core-collapse SNe to be conducted through future wide-field transient searches.

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