- ID:
- ivo://CDS.VizieR/J/ApJ/890/86
- Title:
- H{alpha} spectra & V-band photometry of {delta} Sco
- Short Name:
- J/ApJ/890/86
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- We model the circumstellar disk of {delta} Sco using the three-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large-scale changes in the disk through the years 2000-2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models through matching simulated observations to actual H{alpha} spectroscopy and V-band photometric observations. Our modeling results confirm previous findings that the disk of {delta}Sco was forming early in the century. We also find a period of disk dissipation when the companion is at apastron, as well as a significant growth of the disk between 2009 and 2011, prior to the periastron of 2011. Due to the steady-state nature of the disk after 2011, it is difficult to say whether the variations seen are due to the effect of the close passage of the binary companion.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/122/248
- Title:
- h and chi Per UBVI,H{alpha} photometry
- Short Name:
- J/AJ/122/248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVI and H{alpha} photometry is presented for 17319 stars in vicinity of the young double cluster h and {chi} Persei. Our photometry extends over a 37'x1{deg} field centered on the association. We construct reddening contours within the imaged field. We find that the two clusters share a common distance modulus of 11.75+/-0.05 and ages of log[age(yr)]=7.1+/-0.1. From the V-H{alpha} color, a measure of the H{alpha} emission strength, we conduct a survey for emission line objects within the association. We detect a sample of 33 Be stars, eight of which are new detections. We present a scenario of evolutionary enhancement of the Be phenomenon to account for the peak in Be fraction toward the top of the main sequence in the population of h and {chi} Persei and similar young clusters. UBVI and H{alpha} photometry was performed on five nights between 1999 August 17 and 25 at the San Diego State University Mount Laguna Observatory with the 1m telescope and a Loral 2048x2048 CCD.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A28
- Title:
- HARPSpol magnetic massive stars
- Short Name:
- J/A+A/567/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A31
- Title:
- HCO+, CN, and 13CO maps of R Mon
- Short Name:
- J/A+A/617/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To our knowledge, R Mon is the only B0 star in which a gaseous Keplerian disk has been detected. However, there is some controversy about the spectral type of R Mon. Some authors propose that it could be a later B8e star, where disks are more common. Our goal is to re-evaluate the R Mon spectral type and characterize its protoplanetary disk. The spectral type of R Mon has been re-evaluated using the available continuum data and UVES emission lines. We used a power-law disk model to fit previous ^12^CO 1-0 and 2-1 interferometric observations and the PACS CO data to investigate the disk structure. Interferometric detections of ^13^CO J=1-0, HCO^+^ 1-0, and CN 1-0 lines using the IRAM Plateau de Bure Interferometer (PdBI) are presented. The HCN 1-0 line was not detected. Our analysis confirms that R Mon is a B0 star. The disk model compatible with the ^12^CO 1-0 and 2-1 interferometric observations falls short of predicting the observed fluxes of the 14<Ju<31 PACS lines; this is consistent with the scenario in which some contribution to these lines is coming from a warm envelope and/or UV-illuminated outflow walls. More interestingly, the upper limits to the fluxes of the Ju>31 CO lines suggest the existence of a region empty of CO at R<=20au in the proto-planetary disk. The intense emission of the HCO^+^ and CN lines shows the strong influence of UV photons on gas chemistry. The observations gathered in this paper are consistent with the presence of a transition disk with a cavity of Rin>=20 au around R Mon. This size is similar to the photoevaporation radius that supports the interpretation that UV photoevaporation is main disk dispersal mechanism in massive stars
- ID:
- ivo://CDS.VizieR/J/A+A/567/A57
- Title:
- HD 161306 H{alpha} and HeI spectra
- Short Name:
- J/A+A/567/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectrum of the Be star HD 161306 is shown to vary periodically with a period of ~100-days. The radial velocity of the HeI 6678{AA} emission peak varying in antiphase to the radial velocity of the H{alpha} emission wings component suggests that the star is a binary similar to {phi} Per, 59 Cyg, or FY CMa, i.e. a radiatively interacting Be binary - a rare case among Be stars. This type of object is also called a {phi} Per-type binary or Be + sdO binaries. The range of radial-velocity variations of the strong emission peak in the helium line observed in HD 161306 is about 180km/s, similar to what is observed for these systems. We therefore conclude that HD 161306 may represent another case of a Be star with a hot subdwarf companion.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A13
- Title:
- HD 50138 short-term variability
- Short Name:
- J/A+A/548/A13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 50138 presents the B[e] phenomenon, but its nature is not clear yet. This star is known to present spectral variations, which have been associated with outbursts and shell phases. We analyze the line profile variability of HD 50138 and its possible origin, which provide possible hints to its evolutionary stage, so far said to be close to the end of (or slightly beyond) the main sequence.
- ID:
- ivo://CDS.VizieR/J/A+A/586/A116
- Title:
- HD50138 time-dependent spectral variations
- Short Name:
- J/A+A/586/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- B[e] stars are anomalous objects around which extended circumstellar matter is present. The observed properties of the central star are significantly affected by the surrounding material. Therefore, the use of standard synthetic spectra is disputable in this case and our capability to study these objects is limited. One of the possibilities is to analyse variations of the spectral features. Long-term spectroscopic observations are required for this, but are not found in the literature. For our study we choose the B[e] star HD 50138 of the FS CMa type because of the indication that this star is a post-main-sequence star, although still not highly evolved. Therefore, it can be a good object for testing evolutionary models. Currently, HD 50138 is the most extensively observed FS CMa star which makes it an ideal object for modelling. Our observations fill the gap in the available data. To describe the variability of HD 50138 we have monitored this star spectroscopically over the last twenty years. To search for the periodicity on short-term scales, series of night-to-night observations were also obtained.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/234
- Title:
- Herbig Ae/Be accretion rates & mechanisms
- Short Name:
- J/MNRAS/493/234
- Date:
- 02 Feb 2022 07:28:24
- Publisher:
- CDS
- Description:
- This work presents a spectroscopic study of 163 Herbig Ae/Be stars. Amongst these, we present new data for 30 objects. Stellar parameters such as temperature, reddening, mass, luminosity, and age are homogeneously determined. Mass accretion rates are determined from H{alpha} emission line measurements. Our data is complemented with the X-Shooter sample from previous studies and we update results using Gaia DR2 parallaxes giving a total of 78 objects with homogeneously determined stellar parameters and mass accretion rates. In addition, mass accretion rates of an additional 85 HAeBes are determined. We confirm previous findings that the mass accretion rate increases as a function of stellar mass, and the existence of a different slope for lower and higher mass stars, respectively. The mass where the slope changes is determined to be 3.98^+1.37_-0.94M_{sun}_. We discuss this break in the context of different modes of disc accretion for low- and high-mass stars. Because of their similarities with T Tauri stars, we identify the accretion mechanism for the late-type Herbig stars with the Magnetospheric Accretion. The possibilities for the earlier-type stars are still open, we suggest the Boundary Layer accretion model may be a viable alternative. Finally, we investigated the mass accretion-age relationship. Even using the superior Gaia based data, it proved hard to select a large enough sub-sample to remove the mass dependence in this relationship. Yet, it would appear that the mass accretion does decline with age as expected from basic theoretical considerations.
- ID:
- ivo://CDS.VizieR/J/AJ/118/1043
- Title:
- Herbig Ae/Be stars catalog
- Short Name:
- J/AJ/118/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVR photometric monitoring of Herbig Ae/Be stars and some related objects has been carried out at Maidanak Observatory in Uzbekistan since 1983. More than 71,000 observations of about 230 stars have been obtained and are made available for anonymous ftp. Virtually all Herbig Ae/Be stars observed are irregular variables (called "UXors" after UX Ori), but there is a wide range of amplitudes from barely detectable to more than 4mag in V. Our data confirm the results of previous studies, which indicate that large-amplitude variability is confined to stars with spectral types later than B8. The distribution of variability ranges is quite similar to what is seen in classical T Tauri stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/836/112
- Title:
- High-resolution spectra of * bet CMi
- Short Name:
- J/ApJ/836/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The late-type Be star {beta} CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement+ (2015A&A...584A..85K). These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is evidence for an unseen binary companion in orbit. Here we report on an analysis of the Ritter Observatory spectroscopic archive of {beta} CMi to search for evidence of the elusive companion. We detect periodic Doppler shifts in the wings of the H{alpha} line with a period of 170 days and an amplitude of 2.25km/s, consistent with a low-mass binary companion (M~0.42M_{sun}_). We then compared small changes in the violet-to-red peak height changes (V/R) with the orbital motion. We find weak evidence that it does follow the orbital motion, as suggested by recent Be binary models by Panoglou et al. Our results, which are similar to those for several other Be stars, suggest that {beta} CMi may be a product of binary evolution where Roche lobe overflow has spun up the current Be star, likely leaving a hot subdwarf or white dwarf in orbit around the star. Unfortunately, no direct sign of this companion star is found in the very limited archive of International Ultraviolet Explorer spectra.