- 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.
Number of results to display per page
Search Results
- 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.
22593. Type II Cepheids
- ID:
- ivo://CDS.VizieR/J/AJ/114/341
- Title:
- Type II Cepheids
- Short Name:
- J/AJ/114/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the photospheric compositions of five luminous F-G variables in globular clusters: V11 in M2, V42 in M5, V84 in M5, V2 in M10, and V17 in M28, three of which are classified as RV Tau variable stars. Unlike the recent findings that the photospheres of field RV Tau variables have been altered by a gas-dust separation process, none of these stars, except possibly V2 in M10, show such signs. We suggest that either a smaller carbon abundance in the photosphere of a globular cluster RV Tau star (compared to its field analogues) might be a factor in the gas-dust separation process due to the lack of sufficient carbon grain formation, or the stellar winds and their efficacy as dust-grain separators is influenced by the metallicity of the stellar envelope which, unlike the photosphere, is never subject to alteration by a dust-gas separation. Our analysis is most complete for V84, for which we have estimated the abundances of 19 chemical elements. Compared to the other giants in M5, this star displays a very large excess of Na and a deficit of O. This finding is consistent with a recently proposed mechanism of Na production in the ON-cycling region of metal-poor RGB stars. The value of [Al/Fe] for V84 is also high (also consistent with ON-cycling), but a comparison with the other cluster giants cannot be performed until Al is measured in their spectra. The s-process elements are not significantly enhanced in the atmosphere of V84 relative to the other cluster members. (c) 1997 American Astronomical Society.
22594. 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/860/68
- Title:
- Type IIn Supernova SN 2010bt photometry
- Short Name:
- J/ApJ/860/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is well known that massive stars (M>8M_{sun}_) evolve up to the collapse of the stellar core, resulting in most cases in a supernova (SN) explosion. Their heterogeneity is related mainly to different configurations of the progenitor star at the moment of the explosion and to their immediate environments. We present photometry and spectroscopy of SN 2010bt, which was classified as a Type IIn SN from a spectrum obtained soon after discovery and was observed extensively for about 2 months. After the seasonal interruption owing to its proximity to the Sun, the SN was below the detection threshold, indicative of a rapid luminosity decline. We can identify the likely progenitor with a very luminous star (log L/L_{sun}_~7) through comparison of Hubble Space Telescope images of the host galaxy prior to explosion with those of the SN obtained after maximum light. Such a luminosity is not expected for a quiescent star, but rather for a massive star in an active phase. This progenitor candidate was later confirmed via images taken in 2015 (~5yr post-discovery), in which no bright point source was detected at the SN position. Given these results and the SN behavior, we conclude that SN 2010bt was likely a Type IIn SN and that its progenitor was a massive star that experienced an outburst shortly before the final explosion, leading to a dense H-rich circumstellar environment around the SN progenitor.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/63
- Title:
- Type IIP SN 2016bkv LCs and spectra
- Short Name:
- J/ApJ/861/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While interaction with circumstellar material is known to play an important role in Type IIn supernovae (SNe), analyses of the more common SNe IIP and IIL have not traditionally included interaction as a significant power source. However, recent campaigns to observe SNe within days of explosion have revealed narrow emission lines of high-ionization species in the earliest spectra of luminous SNe II of all subclasses. These "flash ionization" features indicate the presence of a confined shell of material around the progenitor star. Here we present the first low-luminosity (LL) SN to show flash ionization features, SN 2016bkv. This SN peaked at MV = -16 mag and has H{alpha} expansion velocities under 1350 km s-1 around maximum light, placing it at the faint/slow end of the distribution of SNe IIP (similar to SN 2005cs). The light-curve shape of SN 2016bkv is also extreme among SNe IIP. A very strong initial peak could indicate additional luminosity from circumstellar interaction. A very small fall from the plateau to the nickel tail indicates unusually large production of radioactive nickel compared to other LL SNe IIP. A comparison between nebular spectra of SN 2016bkv and models raises the possibility that SN 2016bkv is an electron-capture supernova.
- 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.
