- ID:
- ivo://CDS.VizieR/J/MNRAS/451/1973
- Title:
- Type Ia supernovae igh-velocity features
- Short Name:
- J/MNRAS/451/1973
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 'High-velocity features' (HVFs) are spectral features in Type Ia supernovae (SNe Ia) that have minima indicating significantly higher (by greater than about 6000km/s) velocities than typical 'photospheric-velocity features' (PVFs). The PVFs are absorption features with minima indicating typical photospheric (i.e. bulk ejecta) velocities (usually~9000-15000km/s near B-band maximum brightness). In this work, we undertake the most in-depth study of HVFs ever performed. The data set used herein consists of 445 low-resolution optical and near-infrared (NIR) spectra (at epochs up to 5d past maximum brightness) of 210 low-redshift SNe Ia that follow the 'Phillips relation'. A series of Gaussian functions is fit to the data in order to characterize possible HVFs of CaII H&K, SiII {lambda}6355, and the CaII NIR triplet. The temporal evolution of the velocities and strengths of the PVFs and HVFs of these three spectral features is investigated, as are possible correlations with other SN Ia observables. We find that while HVFs of CaII are regularly observed (except in underluminous SNe Ia, where they are never found), HVFs of Siii {lambda}6355 are significantly rarer, and they tend to exist at the earliest epochs and mostly in objects with large photospheric velocities. It is also shown that stronger HVFs of SiII {lambda}6355 are found in objects that lack CII absorption at early times and that have red ultraviolet/optical colours near maximum brightness. These results lead to a self-consistent connection between the presence and strength of HVFs of SiII {lambda}6355 and many other mutually correlated SN Ia observables, including photospheric velocity.
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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.
- 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/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.
- ID:
- ivo://CDS.VizieR/J/PAZh/27/841
- Title:
- UBV and line identification of V1853 Cyg
- Short Name:
- J/PAZh/27/841
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric and spectroscopic observations of the protoplanetary object V1853 Cyg, a B supergiant with an IR excess, are given. The observations were carried out with a UBV photometer attached to the 60-cm Zeiss telescope at the Crimean Station of the Stenberg Astronomical Institute.
- ID:
- ivo://CDS.VizieR/J/A+A/531/A49
- Title:
- UBV and spectroscopic variations of V2368 Oph
- Short Name:
- J/A+A/531/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The A-type star HR 6412 = V2368 Oph was used by several investigators as a photometric comparison star for the known eclipsing binary U Oph but was found to be variable by three independent groups, including us. By analysing series of new spectral and photometric observations and a critical compilation of available radial velocities, we were able to find the correct period of light and radial-velocity variations and demonstrate that the object is an eclipsing and double-lined spectroscopic binary moving in a highly eccentric orbit. We derived a linear ephemeris Tmin.I=HJD(2454294.67+/-0.01)+(38.32712+/-0.00004)d*E and estimated preliminary basic physical properties of the binary.
- ID:
- ivo://CDS.VizieR/J/PAZh/32/737
- Title:
- UBV light curve and spectroscopy of StHa62
- Short Name:
- J/PAZh/32/737
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric observations of HD 51585 (OY Gem), a B[e] star with an infrared excess and a candidate for protoplanetary nebulae, obtained with a 60-cm telescope at the Crimean Station of Sternberg Astronomical Institute in 1992-2005 are presented. The star exhibited rapid irregular brightness variations with amplitudes from 0.1mag in the V band to 0.2mag in the U band within the observing season as well as slow systematic variations. with a quasi-period of ~2800-days. Low-resolution spectroscopy performed in 1994-2005 has revealed significant variability of the Balmer and Paschen hydrogen emission lines as well as the HeI and OI lines. Equivalent widths are given for the HI, HeI, OI, and FeII lines. Correlation has been found between the star's photometric variability and the hydrogen line intensities.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/30
- Title:
- UBV photometry of IRAS 18062+2410
- Short Name:
- J/PAZh/25/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photometric and spectroscopic observations of IRAS 18062+2410 = V886 Her, a candidate for protoplanetary objects, in 1996-1997 are presented. The star exhibits rapid light variations with an amplitude up to 0.3mag in V. A high-resolution spectrum of IRAS shows absorption lines of H, HeI, OI, FeII, SiII, NaI and other species, including [OII], [NII], and [FeII] that belong to the stellar envelope.
- ID:
- ivo://CDS.VizieR/J/AZh/79/309
- Title:
- UBVR and spectroscopic observations of CI Cam
- Short Name:
- J/AZh/79/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric (UBVR) observations in 1998-2001 and medium-resolution spectroscopy obtained in the SAO in the same period for the B[e]/X-ray transient CI Cam display cyclic variations with a period of 1100 days.
- ID:
- ivo://CDS.VizieR/J/A+A/434/1107
- Title:
- UBV(RI)c photometry of stars around V838 Mon
- Short Name:
- J/A+A/434/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extensive optical and infrared photometry as well as low and high resolution spectroscopy are used as inputs in deriving robust estimates of the reddening, distance and nature of the progenitor of V838 Mon, the 2002 outbursting event that produced a most spectacular light-echo.
