- 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.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/392/448
- Title:
- Rotational velocities of early-type binaires
- Short Name:
- J/MNRAS/392/448
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use information on the vsin(i) values of early-type binaries in order to search for correlations which may constrain the relative orientation of the stellar spin axes in binary systems. We find correlations in the case of close binaries which suggest that tidal synchronization is effective for binaries whose separation exceeds the stellar radius by more than an order of magnitude, in line with the theoretical predictions of Goldreich & Nicholson (1989ApJ...342.1079G) and the previous observational analysis of Giuricin et al. (1984A&A...135..393G). In the case of wide binaries, the vsin(i) values are not well correlated, which requires that the magnitude of the spin speeds is not tightly correlated. Under this assumption, we then find that the data provide no significant constraints on the degree of alignment of spin axes. The data are therefore compatible with scenarios (such as disc fragmentation or capture) which differ widely in the expected degree of spin alignment.
- ID:
- ivo://CDS.VizieR/J/AJ/144/130
- Title:
- Rotational velocities of nearby HIP B stars
- Short Name:
- J/AJ/144/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Projected rotational velocities (vsini) are presented for a sample of 350 early B-type main-sequence stars in the nearby Galactic disk. The stars are located within ~1.5kpc from the Sun, and the great majority within 700pc. The analysis is based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan Clay 6.5m telescope at the Las Campanas Observatory in Chile. Spectral types were estimated based on relative intensities of some key line absorption ratios and comparisons to synthetic spectra. Effective temperatures were estimated from the reddening-free Q index, and projected rotational velocities were then determined via interpolation on a published grid that correlates the synthetic FWHM of the He_I_ lines at 4026, 4388 and 4471{AA} with vsini. As the sample has been selected solely on the basis of spectral types, it contains a selection of B stars in the field, in clusters, and in OB associations. The vsini distribution obtained for the entire sample is found to be essentially flat for vsini values between 0 and 150km/s, with only a modest peak at low projected rotational velocities. Considering subsamples of stars, there appears to be a gradation in the vsini distribution with the field stars presenting a larger fraction of the slow rotators and the cluster stars distribution showing an excess of stars with vsini between 70 and 130km/s. Furthermore, for a subsample of potential runaway stars we find that the vsini distribution resembles the distribution seen in denser environments, which could suggest that these runaway stars have been subject to dynamical ejection mechanisms.
- ID:
- ivo://CDS.VizieR/J/ApJ/700/844
- Title:
- Rotation rates of very massive stars
- Short Name:
- J/ApJ/700/844
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present projected rotational velocity values for 96 Galactic, 55 SMC, and 106 LMC O-B type stars from archival FUSE observations. The evolved and unevolved samples from each environment are compared through the Kolmogorov-Smirnov test to determine if the distribution of equatorial rotational velocities is metallicity dependent for these massive objects. Stellar interior models predict that massive stars with SMC metallicity will have significantly reduced angular momentum loss on the main sequence compared to their Galactic counterparts. Our results find some support for this prediction but also show that even at Galactic metallicity, evolved and unevolved massive stars have fairly similar fractions of stars with large Vsin i values. Macroturbulent broadening that is present in the spectral features of Galactic evolved massive stars is lower in the LMC and SMC samples. This suggests the processes that lead to macroturbulence are dependent upon metallicity.
- ID:
- ivo://CDS.VizieR/J/AJ/129/2018
- Title:
- RXTE scaled fluxes of eta Car
- Short Name:
- J/AJ/129/2018
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present monitoring observations by the Rossi X-Ray Timing Explorer of the 2-10keV X-ray emission from the supermassive star {eta} Carinae from 1996 through late 2003. These data cover more than one of the stellar variability cycles in temporal detail and include especially detailed monitoring through two X-ray minima.
- ID:
- ivo://CDS.VizieR/J/A+A/595/A31
- Title:
- SAM detection limits of 8 debris disks
- Short Name:
- J/A+A/595/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse aperture masking (SAM) is a high angular resolution technique strongly contributing to probing the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low-mass companions, or to set detection limits. We observed eight stars presenting debris disks ({beta} Pictoris, AU Microscopii, 49 Ceti, {eta} Telescopii, Fomalhaut, g Lupi, HD 181327, and HR 8799) with SAM technique on the NaCo instrument at the Very Large Telescope (VLT). No close companions were detected using closure phase information under 0.5" of separation from the parent stars. We obtained magnitude detection limits that we converted to Jupiter masses detection limits using theoretical isochrones from evolutionary models. We derived upper mass limits on the presence of companions in the area of a few times the telescope's diffraction limits around each target star.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A160
- Title:
- SEDIGISM survey, search for molecular outflows
- Short Name:
- J/A+A/658/A160
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The formation processes of massive stars are still unclear but a picture is emerging involving accretion disks and molecular outflows in what appears to be a scaled-up version of lower-mass star formation. A census of outflow activity towards high-mass star-forming clumps in various evolutionary stages has the potential to shed light on high-mass star formation. We conduct an outflow survey toward ATLASGAL (APEX Telescope Large Area Survey of the Galaxy) clumps, using SEDIGISM (structure, Excitation, and Dynamics of the Inner Galactic InterStellar Medium) data and aim to obtain a large sample of clumps exhibiting outflow activity in different evolutionary stages. We identify the high-velocity wings of the ^13^CO lines, indicating outflow activity, toward ATLASGAL clumps by (1) extracting the simultaneously observed ^13^CO(2-1) and C^18^O(2-1) spectra from SEDIGISM, and (2) subtracting the scaled C^18^O (cores emission) from the ^13^CO, after considering opacity broadening. We have detected high-velocity gas towards 1192 clumps out of a total sample of 2052 corresponding to an overall detection rate of 58%. Outflow activity has been detected from the earliest (apparently) quiescent clumps (i.e., 70 microns weak), to the most evolved HII region stages (i.e., 8 micron bright with tracers of massive star formation). The detection rate increases as a function of evolution (quiescent = 51%, protostellar = 47%, YSO = 57%, UCHII regions = 76%). Our sample is the largest outflow sample identified so far. The high detection rate from this large sample is consistent with the results of similar studies reported in the literature and supports the scenario that outflows are a ubiquitous feature of high-mass star formation. The lower detection rate in early evolutionary stages could be due to the fact that outflows in the early stages are weak and difficult to detect. We obtain a statistically significant number of outflow clumps for every evolutionary stage, especially for outflow clumps in the earliest stages (i.e., 70 microns dark cloud or massive starless core).
- ID:
- ivo://CDS.VizieR/J/A+A/650/A39
- Title:
- SOPHIE and HARPS Young Nearby Stars - YNS
- Short Name:
- J/A+A/650/A39
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The search of close (a<~5au) giant planet (GP) companions with radial velocity (RV) around young stars and the estimate of their occurrence rates is important to constrain the migration timescales. Furthermore, this search will allow the giant planet occurrence rates to be computed at all separations via the combination with direct imaging techniques. The RV search around young stars is a challenge as they are generally faster rotators than older stars of similar spectral types and they exhibit signatures of magnetic activity (spots) or pulsation in their RV time series. Specific analyses are necessary to characterize, and possibly correct for, this activity. Our aim is to search for planets around young nearby stars and to estimate the GP occurrence rates for periods up to 1000 days. We used the SOPHIE spectrograph on the 1.93m telescope at the Haute-Provence Observatory to observe 63 A-M young (<400Myr) stars. We used our Spectroscopic data via Analysis of the Fourier Interspectrum Radial velocities (SAFIR) software to compute the RVs and other spectroscopic observables. We then combined this survey with the HARPS YNS survey to compute the companion occurrence rates on a total of 120 young A-M stars. Results. We report one new trend compatible with a planetary companion on HD 109647. We also report HD 105693 and HD 112097 as binaries, and we confirm the binarity of HD 2454, HD13531, HD 17250 A, HD 28945, HD 39587, HD 131156, HD 142229, HD 186704 A, and HD 195943. We constrained for the first time the orbital parameters of HD 195943 B. We refute the HD 13507 single brown dwarf (BD) companion solution and propose a double BD companion solution. Two GPs were previously reported from this survey in the HD 113337 system. Based on our sample of 120 young stars, we obtain a GP occurrence rate of 1^+2/2^_0/3_% for periods lower than 1000 days, and we obtain an upper limit on BD occurrence rate of 0.9^+2^_0.9_% in the same period range. We report a possible lack of close (P {in} [1; 1000] days) GPs around young FK stars compared to their older counterparts, with a confidence level of 90%.
- ID:
- ivo://CDS.VizieR/J/ApJ/713/871
- Title:
- Sources in star-forming region Cyg-OB2 from X-ray
- Short Name:
- J/ApJ/713/871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cygnus OB2 is the nearest example of a massive star-forming region (SFR), containing over 50 O-type stars and hundreds of B-type stars. We have analyzed the properties of young stars in two fields in Cyg OB2 using the recently published deep catalog of Chandra X-ray point sources with complementary optical and near-IR photometry. Our sample is complete to ~1M_{sun}_ (excluding A- and B-type stars that do not emit X-rays), making this the deepest study of the stellar properties and star formation history in Cyg OB2 to date. Combining our stellar mass function (MF) and an estimate of the radial density profile of the association suggests a total mass of Cyg OB2 of ~3x10^4^M_{sun}_, similar to that of many of our Galaxy's most massive SFRs.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/401
- Title:
- Southern peculiar early-type stars polarimetry
- Short Name:
- J/A+AS/131/401
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and discuss optical polarimetry of a large group (60 objects) of peculiar early-type stars (Herbig Ae/Be stars and candidate members, B[e] stars, extreme emission line objects etc.). Most were taken from ``A new catalogue of members and candidate members of Herbig Ae/Be stellar group'' The et al. (1994, Cat. <J/A+AS/104/315>). For 40 out of the 60 objects polarization was measured for the first time. On the basis of the data we draw conclusions about the circumstellar shell configuration and orientation for several objects. Polarimetric variability on different time-scales (minutes...hours...days) was investigated, as well as comparison with earlier measurements to investigate variability over longer time-scales. No circular polarization was detected to a 5{sigma} level in most of the investigated stars. Polarimetric data obtained here as well as data available from the literature were analyzed from the point of investigating the evolutionary status of the objects. The relationship between the polarimetric and photometric data was also investigated.
