- ID:
- ivo://CDS.VizieR/J/A+A/508/309
- Title:
- Spectral atlas of HD 50138
- Short Name:
- J/A+A/508/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The observed spectral variation of HD50138 led different authors in the literature to classify it in a very large range of spectral types and luminosity classes (from B5 to A0 and III to Ia) and at different evolutionary stages, as either an HAeBe star or a classical Be. Based on new high-resolution optical spectroscopic data from 1999 and 2007, we perform a detailed spectral description, presenting the variations seen and discussing their possible origin. We tentatively suggest that a new shell phase could have taken place prior to our observations in 2007. We derive the interstellar extinction to HD50138 by taking into account the influences of the circumstellar matter in the form of dust and an ionized disk. We find a color excess value of E(B-V)=0.08mag. Based on photometric data from the literature and the new Hipparcos distance, we obtain a revised set of parameters for HD50138, suggesting that it is a B6-7 III-V star. A discussion about the different evolutionary scenarios is also provided.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/465/993
- Title:
- Spectral atlas of massive stars around He I
- Short Name:
- J/A+A/465/993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a digital atlas of peculiar, high-luminosity massive stars in the near-infrared region (10470-11000{AA}) at medium resolution (R~7000). The spectra are centered around HeI 10830{AA}, which is formed in the wind of those stars, and is a crucial line to obtain their physical parameters. The instrumental configuration also sampled a rich variety of emission lines of FeII, MgII, CI, NI, and Pa{gamma}. Secure identifications for most spectral lines are given, based on synthetic atmosphere models calculated by our group. We also propose that two unidentified absorption features have interstellar and/or circumstellar origin. For the strongest one (10780{AA}) an empirical calibration between E(B-V) and equivalent width is provided. The atlas displays the spectra of massive stars organized in four categories, namely Be stars, OBA Iape (or luminous blue variables, LBV candidates and ex/dormant LBVs), OB supergiants and Wolf-Rayet stars. For comparison, the photospheric spectra of non emission-line stars are presented. Selected LBVs were observed in different epochs from 2001 to 2004, and their spectral variability reveals that some stars, such as eta Car, AG Car and HR Car, suffered dramatic spectroscopic changes during this time interval.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/120
- Title:
- Spectropolarimetric survey of classical Be stars
- Short Name:
- J/ApJ/786/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent observational and theoretical studies of classical Be stars have established the utility of polarization color diagrams (PCDs) in helping to constrain the time-dependent mass decretion rates of these systems. We expand on our pilot observational study of this phenomenon, and report the detailed analysis of a long-term (1989-2004) spectropolarimetric survey of nine additional classical Be stars, including systems exhibiting evidence of partial disk-loss/disk-growth episodes as well as systems exhibiting long-term stable disks. After carefully characterizing and removing the interstellar polarization along the line of sight to each of these targets, we analyze their intrinsic polarization behavior. We find that many steady-state Be disks pause at the top of the PCD, as predicted by theory. We also observe sharp declines in the Balmer jump polarization for later spectral type, near edge-on steady-state disks, again as recently predicted by theory, likely caused when the base density of the disk is very high, and the outer region of the edge-on disk starts to self absorb a significant number of Balmer jump photons. The intrinsic V-band polarization and polarization position angle of {gamma} Cas exhibits variations that seem to phase with the orbital period of a known one-armed density structure in this disk, similar to the theoretical predictions of Halonen & Jones. We also observe stochastic jumps in the intrinsic polarization across the Balmer jump of several known Be+sdO systems, and speculate that the thermal inflation of part of the outer region of these disks could be responsible for producing this observational phenomenon. Finally, we estimate the base densities of this sample of stars to be between ~8x10^-11^ and ~4x10^-12^ g/cm^3^ during quasi steady state periods given there maximum observed polarization.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/1306
- Title:
- Spectropolarimetry of 60 Cyg and {pi} Aqr
- Short Name:
- J/ApJ/709/1306
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Classical Be stars are known to occasionally transition from having a gaseous circumstellar disk ("Be phase") to a state in which all observational evidence for the presence of these disks disappears ("normal B-star phase"). We present one of the most comprehensive spectropolarimetric views to date of such a transition for two Be stars, {pi} Aquarii and 60 Cygni. The disk-loss episode of 60 Cyg was characterized by a generally monotonic decrease in emission strength over a timescale of ~1000 days from the maximum V-band polarization to the minimum H{alpha} equivalent width, consistent with the viscous timescale of the disk, assuming {alpha}~0.14. {pi} Aqr's disk loss was episodic in nature and occurred over a timescale of ~2440 days.
- ID:
- ivo://CDS.VizieR/J/A+A/477/877
- Title:
- Spectroscopic analysis of RJHA 49 and SS73 21
- Short Name:
- J/A+A/477/877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spectra and the evolutionary stages of two peculiar emission-line stars: RJHA 49 and SS73 21. We used low and high resolution optical data. Line identifications and measurements were performed for several features in their spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/328/551
- Title:
- Spectroscopic data of 4 Herculis
- Short Name:
- J/A+A/328/551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A collection of spectroscopic data of 4 Her at our disposal (RV and spectrophotometric measurements) consist of spectra obtained at the Ondrejov and Haute Provence Observatories. Table 1 summarizes the measurements of radial velocities and line intensities carried out in the red spectra. In Table 2 a list of the spectra and RV measurements for the violet-blue region is given.
- ID:
- ivo://CDS.VizieR/J/A+A/378/861
- Title:
- Spectroscopy of Be stars
- Short Name:
- J/A+A/378/861
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 270 spectra enclosed are those used in the atlas and are described in the Table 1 of the paper: stars with magnitudes and spectral types, dates of observations and other data. All are normalized and corrected from the radial velocity due to Earth movement, but not corrected from the radial velocity of the star itself. The heliocentric Julian day of the mid-exposure appears in the header with a comment keyword. Very often it cannot be derived by a simple formula from the beginning and the time exposure, when the spectrum is the result of the sum of several successive ones, or when clouds have obliged to interrupt the exposure. For this reason, it is always indicated. The HD number of the star appears always in the name of the file, with additional letters to distinguish the different spectra of a same star. The tracings of the atlas (72 FITS files) are described in the subsection 2.4 of the paper and available with the electronic version.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/1216
- Title:
- Spectroscopy of Be stars in open clusters
- Short Name:
- J/ApJ/700/1216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We recently discovered a large number of highly active Be stars in the open cluster NGC 3766, making it an excellent location to study the formation mechanism of Be star disks. To explore whether similar disk appearances and/or disappearances are common among the Be stars in other open clusters, we present here multiple epochs of H{alpha} spectroscopy for 296 stars in eight open clusters. We identify 12 new transient Be stars and confirm 17 additional Be stars with relatively stable disks. By comparing the H{alpha} equivalent widths to the photometric y-H{alpha} colors, we present a method to estimate the strength of the H{alpha} emission when spectroscopy is not available. For a subset of 128 stars in four open clusters, we also use blue optical spectroscopy and available Stromgren photometry to measure their projected rotational velocities, effective temperatures, and polar surface gravities. We combine our Be star detections from these four clusters to investigate physical differences between the transient Be stars, stable Be stars, and normal B-type stars with no line emission. Both types of Be stars are faster rotating populations than normal B-type stars, and we find no significant physical differences between the transient and stable Be stars in our sample.
- ID:
- ivo://CDS.VizieR/J/other/BASI/39.517
- Title:
- Spectroscopy of classical Be stars
- Short Name:
- J/other/BASI/39.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic study of 150 Classical Be stars in 39 open clusters using medium resolution spectra in the wavelength range 3800-9000{AA}. One-third of the sample (48 stars in 18 clusters) has been studied for the first time. All these candidates were identified from an extensive survey of emission stars in young open clusters using slitless spectroscopy (Mathew et al., 2008MNRAS.388.1879M). This large data set covers CBe stars of various spectral types and ages found in different cluster environments in largely northern open clusters, and is used to study the spectral characteristics of CBe stars in cluster environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/209
- Title:
- Spectroscopy of the B[e] star VES 695
- Short Name:
- J/ApJ/700/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- FS CMa type stars are a group of Galactic objects with the B[e] phenomenon. They exhibit strong emission-line spectra and infrared excesses, which are most likely due to recently formed circumstellar dust. The group content and identification criteria were described in the first two papers of the series. In this paper we report our spectroscopic and photometric observations of the optical counterpart of IRAS 00470+6429 obtained in 2003-2008. The optical spectrum is dominated by emission lines, most of which have P Cyg type profiles. We detected significant brightness variations, which may include a regular component, and variable spectral line profiles in both shape and position. The presence of a weak LiI6708{AA} line in the spectrum suggests that the object is most likely a binary system with a B2-B3 spectral-type primary companion of a luminosity logL/L_{sun}_=3.9+/-0.3 and a late-type secondary companion. We estimate a distance toward the object to be 2.0+/-0.3kpc from the Sun.
