- ID:
- ivo://CDS.VizieR/J/AN/331/349
- Title:
- O, B-type & red supergiant masses and luminosities
- Short Name:
- J/AN/331/349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars are of interest as progenitors of supernovae, i.e. neutron stars and black holes, which can be sources of gravitational waves. Recent population synthesis models can predict neutron star and gravitational wave observations but deal with a fixed supernova rate or an assumed initial mass function for the population of massive stars. Here we investigate those massive stars, which are supernova progenitors, i.e. with O- and early B-type stars, and also all supergiants within 3kpc. We restrict our sample to those massive stars detected both in 2MASS and observed by Hipparcos, i.e. only those stars with parallax and precise photometry. To determine the luminosities we calculated the extinctions from published multi-colour photometry, spectral types, luminosity class, all corrected for multiplicity and recently revised Hipparcos distances. We use luminosities and temperatures to estimate the masses and ages of these stars using different models from different authors.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/805/94
- Title:
- Periodicities in KIC 3527751 from 3yr Kepler data
- Short Name:
- J/ApJ/805/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze 3yr of nearly continuous Kepler spacecraft short cadence observations of the pulsating subdwarf B (sdB) star KIC 3527751. We detect a total of 251 periodicities, most in the g-mode domain, but some where p-modes occur, confirming that KIC3527751 is a hybrid pulsator. We apply seismic tools to the periodicities to characterize the properties of KIC3527751. Techniques to identify modes include asymptotic period spacing relationships, frequency multiplets, and the separation of multiplet splittings. These techniques allow for 189 (75%) of the 251 periods to be associated with pulsation modes. Included in these are three sets of l=4 multiplets and possibly an l=9 multiplet. Period spacing sequences indicate l=1 and 2 overtone spacings of 266.4+/-0.2 and 153.2+/-0.2s, respectively. We also calculate reduced periods, from which we find evidence of trapped pulsations. Such mode trappings can be used to constrain the core/atmosphere transition layers. Interestingly, frequency multiplets in the g-mode region, which sample deep into the star, indicate a rotation period of 42.6+/-3.4days while p-mode multiplets, which sample the outer envelope, indicate a rotation period of 15.3+/-0.7days. We interpret this as differential rotation in the radial direction with the core rotating more slowly. This is the first example of differential rotation for a sdB star.
- ID:
- ivo://CDS.VizieR/J/ApJ/787/163
- Title:
- Photometric data for SN 2009ip
- Short Name:
- J/ApJ/787/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in 2012 September until 2013 November. These data were collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous circumstellar material (CSM) produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow H{alpha} flux from CSM interactions declines, the broad component of H{alpha} persists with supernova (SN)-like velocities that are not typically seen in LBVs or SN impostor events. At late times, we find that SN 2009ip continues to decline slowly, at <~0.01 mag/day, with small fluctuations in slope similar to Type IIn supernovae (SNe IIn) or SN impostors but no further LBV-like activity. The late-time spectrum features broad calcium lines similar to both late-time SNe and SN impostors. In general, we find that the photometric and spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either continued eruptions of an LBV star or SN impostors but we cannot rule out a nonterminal explosion. In this context, we discuss the implications for episodic mass loss during the late stages of massive star evolution.
- ID:
- ivo://CDS.VizieR/J/A+A/638/A108
- Title:
- 4 p-mode pulsators arrival times
- Short Name:
- J/A+A/638/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate variations in the arrival time of coherent stellar pulsations due to the light travel time effect to test for the presence of sub-stellar companions. Those companions are the key to one possible formation scenario of apparently single subdwarf B stars. We make use of an extensive set of ground-based observations of the four large amplitude p-mode pulsators DW Lyn, V1636 Ori, QQ Vir and V541 Hya. Observations of the TESS space telescope are available on two of the targets. The timing method compares the phase of sinusoidal fits to the full multi-epoch ligh curves with phases from the fit of a number of subsets of the original time series. TESS observations do not sample the pulsations well enough to be useful due to the (currently) fixed 2 minute cadence. From the ground- based observations, we infer evolutionary parameters from the arrival times. The residual signals show many statistically significant periodic signals, but no clear evidence for changes in arrival time induced by sub-stellar companions. The signals can be explained partly by mode beating effects. We derive upper limits on companion masses set by the observational campaign.
- ID:
- ivo://CDS.VizieR/J/other/NatAs/6.154
- Title:
- Polarimetric asteroseismology of beta Crucis
- Short Name:
- J/other/NatAs/6.
- Date:
- 31 Jan 2022 09:03:48
- Publisher:
- CDS
- Description:
- Here we report the detection of polarization variations due to nonradial modes in the {beta} Cephei star {beta} Crucis. In so doing we confirm 40- year-old predictions of pulsation-induced polarization variability and its utility in asteroseismology for mode identification. In an approach suited to other {beta} Cephei stars, we combine polarimetry with space-based photometry and archival spectroscopy to identify the dominant nonradial mode in polarimetry, f2, as l=3, m=-3 (in the m-convention of Dziembowski, 1977AcA.....27..203D) and determine the stellar axis position angle as 25 (or 205) +/-8 degrees. The rotation axis inclination to the line of sight was derived as approx. 46 degrees from combined polarimetry and spectroscopy, facilitating identification of additional modes and allowing for asteroseismic modelling. This reveals a star of 14.5+/-0.5M_{sun}_ and a convective core containing approx. 28 percent of its mass - making {beta} Crucis the most massive star with an asteroseismic age.
- ID:
- ivo://CDS.VizieR/J/A+A/448/1001
- Title:
- Radial velocities of B stars in Sco-Cen
- Short Name:
- J/A+A/448/1001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive single-epoch radial velocities for a sample of 56 B-type stars members of the subgroups Upper Scorpius, Upper Centaurus Lupus and Lower Centaurus Crux of the nearby Sco-Cen OB association. The radial velocity measurements were obtained by means of high-resolution echelle spectra via analysis of individual lines. The internal accuracy obtained in the measurements is estimated to be typically 2-3km/s, but depends on the projected rotational velocity of the target. Radial velocity measurements taken for 2-3 epochs for the targets HD120307, HD142990 and HD139365 are variable and confirm that the y are spectroscopic binaries, as previously identified in the literature. Spectral lines from two stellar components are resolved in the observed spectra of target stars HD133242, HD133955 and HD143018, identifying them as spectroscopic binaries.
- ID:
- ivo://CDS.VizieR/J/A+A/553/A27
- Title:
- Radial velocities of the HgMn star HD 11733
- Short Name:
- J/A+A/553/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals some possible evidence that a very weak differential rotation is operating in HD 11753.
- ID:
- ivo://CDS.VizieR/J/A+A/450/1149
- Title:
- Radial velocity curve of Balloon 090100001
- Short Name:
- J/A+A/450/1149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained 2552 useful low-resolution spectra of the bright sdBV Balloon 090100001, which form the first large time-resolved spectroscopic dataset of this brightest known pulsating subdwarf B star. The data were obtained at the Nordic Optical Telescope during 7 nights in August/September 2004 over a total time base of 38 nights, aiming to derive pulsational characteristics of this star. In this paper we present the observations and the results obtained from frequency analyses. In our data we find clear evidence for 8 independent frequencies, that were all previously reported in photometric monitoring studies, allowing future asteroseismological studies of this star to be constrained by combined photometric and spectroscopic observations of as much as 8 pulsation modes. We do not find conclusive evidence for new frequencies. We present the first determination of the pulsational radial-velocity amplitudes of this star, and find that the radial-velocity amplitude of the main pulsation mode (f_1_=2.80749mHz) in Balloon 090100001 is 18.9km/s, which is the largest radial-velocity amplitude found in sdB-star pulsations so far.
- ID:
- ivo://CDS.VizieR/J/A+A/317/871
- Title:
- Revised spectral types of B-supergiants in the SMC
- Short Name:
- J/A+A/317/871
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The problem of the classification of metal poor stars, such as occur in the Small Magellanic Cloud (SMC), is discussed with reference to the applicability of the MK system in such an environment. An alternative method is presented here and applied to B-type supergiants in the SMC. A local reference system is first devised and then a transformation to MK spectral types is determined by comparing the trends of metal line strengths in these two systems. For the determination of the luminosity class, we emphasize the need to use the hydrogen Balmer line strengths independently of metal line-strength considerations. This method is used to determine new spectral types for 64 supergiants in the SMC, 75% of the sample requiring classifications different from previous findings. These new types result in much improved line strength - spectral type correlations for He, C, N, O, Mg and Si. Corresponding changes in the distribution of these stars in the Hertzsprung-Russell diagram of the SMC reveal more clearly than before the existence of a ridge which may be the SMC analogue of a similar feature found for the LMC by Fitzpatrick & Garmany (1990ApJ...363..119F). The group of very luminous supergiants lying above this ridge includes the LBV AV415 (R40), a property which this object has in common with LBVs in the Large Magellanic Cloud. Also, for the first time, clear examples of BN/BC supergiants are found in the SMC.
- ID:
- ivo://CDS.VizieR/J/ApJ/573/359
- Title:
- Rotational velocities of B stars from BSC
- Short Name:
- J/ApJ/573/359
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The projected rotational velocities of 1092 northern B stars listed in the Bright Star Catalogue (BSC, cat. <V/50>) have been observed with the Kitt Peak 0.9m Coude feed telescope and 2.1 m coude spectrograph, equipped with a 632 grooves/mm grating giving a resolution of 7.1km/s. The rotational velocities were calibrated against the Slettebak et al. (1975ApJS...29..137S) system. The comparison with the BSC velocities shows that the published values of B dwarfs in the BSC average 27% higher than those standards.
