- ID:
- ivo://CDS.VizieR/III/134
- Title:
- Radial Velocities of Bright Population II F Stars
- Short Name:
- III/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents new radial velocity determinations, based on 2nm/mm Coude plates, for 146 southern stars brighter than m(v)=8.3. Drawn from the catalog of uvby-{beta} photometry of southern A5-G0 stars by Olsen (1983, Cat. II/90), the program stars are certain or suspected Population II stars. One triple-lined and 10 double-lined binaries have been detected, including HD 210737, for which a preliminary orbit has been derived. Notes on spectral peculiarities are given. The catalog is in two files. The first file lists HD number, heliocentric Julian date of observation, radial velocity with error and number of lines observed for both the primary and secondary stars, rotation class, and remarks for each observation. The second file contains additional remarks to the data of the first file, sorted by HD number.
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- ID:
- ivo://CDS.VizieR/J/A+AS/137/273
- Title:
- Reference A0V stars
- Short Name:
- J/A+AS/137/273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hipparcos data for 71 nearby dwarf A0 stars were combined with other data, in particular with high resolution spectra to establish the HR diagram in this temperature range. Almost 30% of unknown binaries were detected and discarded before establishing the M-L relation for bright A0 V field stars. The relationship derived for these single stars is compared to the classical diagram derived from eclipsing binaries. The scatter of the latter is examined and the role of gravity is discussed. A good agreement is found between the evolution-based surface gravity logg_ev_ and the value of logg_ph_ obtained from photometric data.
- ID:
- ivo://CDS.VizieR/J/AJ/160/111
- Title:
- RI light curve of KELT-25 and KELT-26
- Short Name:
- J/AJ/160/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discoveries of KELT-25b (TIC 65412605, TOI-626.01) and KELT-26b (TIC 160708862, TOI-1337.01), two transiting companions orbiting relatively bright, early A stars. The transit signals were initially detected by the KELT survey and subsequently confirmed by Transiting Exoplanet Survey Satellite (TESS) photometry. KELT-25b is on a 4.40day orbit around the V=9.66 star CD-245016 (Teff=8280_-180_^+440^K, M{star}=2.18_-0.11_^+0.12^M{sun}), while KELT-26b is on a 3.34day orbit around the V=9.95 star HD134004 (Teff=8640_-240_^+500^K, M{star}=1.93_-0.16_^+0.14^M{sun}), which is likely an Am star. We have confirmed the substellar nature of both companions through detailed characterization of each system using ground-based and TESS photometry, radial velocity measurements, Doppler tomography, and high-resolution imaging. For KELT-25, we determine a companion radius of RP=1.64_-0.043_^+0.039^RJ and a 3{sigma} upper limit on the companion's mass of ~64MJ. For KELT-26b, we infer a planetary mass and radius of MP=1.41_-0.51_^+0.43^M_J_ and RP=1.94_-0.058_^+0.060^RJ. From Doppler tomographic observations, we find KELT-26b to reside in a highly misaligned orbit. This conclusion is weakly corroborated by a subtle asymmetry in the transit light curve from the TESS data. KELT-25b appears to be in a well-aligned, prograde orbit, and the system is likely a member of the cluster Theia449.
- ID:
- ivo://CDS.VizieR/J/A+A/346/586
- Title:
- Rotating models of A and F stars
- Short Name:
- J/A+A/346/586
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnitude differences between rotating and non-rotating copartners for a grid of models with solar metallicity are tabulated here. The results are expressed in terms of the dimensionless angular velocity w-bar- defined in Eq.(1) of the paper, the angle of inclination i and the atmospheric parameters T_e_ and g_e_ defined in Eqs.(22) and (21), respectively. To obtain the absolute magnitudes for a given rotating model, the magnitudes of a non-rotating model with T_eff_=T_e_, g=g_e_ and the same intrinsic luminosity must be added. Results are given for the filters in the Geneva, Johnson and Stroemgren systems. Eq (1): w-bar = {Omega}/{Omega}_c_, where {Omega} is the angular velocity of the star, and {Omega}_c_^2^=8GM/(27R^3^_p_), where M is the mass and R_p_ the polar radius.
- ID:
- ivo://CDS.VizieR/J/A+A/381/105
- Title:
- Rotational velocities of A-type stars. I.
- Short Name:
- J/A+A/381/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Within the scope of a Key Programme determining fundamental parameters of stars observed by HIPPARCOS, spectra of 525 B8 to F2-type stars brighter than V=8 have been collected at ESO. Fourier transforms of several line profiles in the range 4200-4500{AA} are used to derive vsini from the frequency of the first zero. Statistical analysis of the sample indicates that measurement error is a function of vsini and this relative error of the rotational velocity is found to be about 6% on average. The results obtained are compared with data from the literature. There is a systematic shift from standard values from Slk_7_5, which are 10 to 12% lower than our findings. Comparisons with other independent vsini values tend to prove that those from Slettebak et al. (1975ApJS...29..137S) are underestimated. This effect is attributed to the presence of binaries in the standard sample of Slettebak et al. (1975ApJS...29..137S), and to the model atmosphere they used.
- ID:
- ivo://CDS.VizieR/J/A+A/463/671
- Title:
- Rotational velocities of A-type stars. III.
- Short Name:
- J/A+A/463/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of vsini of B9 to F2-type main sequence single stars has been built from highly homogeneous vsini parameters determined for a large sample cleansed of objects presenting the Am and Ap phenomenon as well as of all known binaries. The aim is to study the distributions of rotational velocities in the mass range of A-type stars for normal single objects. Robust statistical methods are used to rectify the vsini distributions for the projection effect and the error distribution. The equatorial velocity distributions are obtained for about 1100 stars divided in six groups defined by the spectral type, under the assumption of randomly orientated rotational axes. We show that late B and early A-type main-sequence stars have genuine bimodal distributions of true equatorial rotational velocities probably due to angular momentum loss and redistribution that the star underwent before reaching the main sequence. A striking lack of slow rotators is noticed among intermediate and late A-type stars.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A120
- Title:
- Rotational velocities of A-type stars. IV.
- Short Name:
- J/A+A/537/A120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In previous works of this series, we have shown that late B- and early A-type stars have genuine bimodal distributions of rotational velocities and that late A-type stars lack slow rotators. The distributions of the surface angular velocity ratio Omega/Omega_crit_ (Omega_crit_ is the critical angular velocity) have peculiar shapes according to spectral type groups, which can be caused by evolutionary properties. We aim to review the properties of these rotational velocity distributions in some detail as a function of stellar mass and age. We have gathered vsini for a sample of 2014 B6- to F2-type stars. We have determined the masses and ages for these objects with stellar evolution models. The (Teff,logL/L_{sun}_)-parameters were determined from the uvby-beta photometry and the HIPPARCOS parallaxes.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A116
- Title:
- Rotation in A-F stars
- Short Name:
- J/A+A/542/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements of projected rotational velocities and the rotational profile of stars with spectral types A-F are presented. This work completes previous measurements by line profile analysis. New spectra with high signal-to-noise ratio were taken with the high-resolution CES and FEROS spectrographs operated by ESO at La Silla, Chile. Stellar rotation is studied in inverse wavelength space analysing the first two zeros of the Fourier transform of the overall broadening profile. Rigid and differential rotation can be distinguished in the case of rapid rotation. New and previous measurements are compiled and made available. The data are supplemented by a homogeneous compilation of basic stellar data from photometry. Data are flagged when there are indications of multiplicity.
- ID:
- ivo://CDS.VizieR/III/22
- Title:
- Rotation of Evolving A and F Stars
- Short Name:
- III/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The authors have studied a vertical strip in the HR diagram covering the range of spectral types A5 through F9. Rotational velocities for a total of 579 stars of all luminosity classes were accumulated. HR number, rotational velocity v sin(i), (b-y) index, m1, c1, reference and group are given. The rotational velocities are also included in the compilation by Uesugi and Fukuda (catalog <III/63>)
- ID:
- ivo://CDS.VizieR/J/ApJ/756/133
- Title:
- ScoCen debris disks around B- and A-type stars
- Short Name:
- J/ApJ/756/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 micron and 70 micron observations of 215 nearby, Hipparcos B- and A-type common proper-motion single and binary systems in the nearest OB association, Scorpius-Centaurus. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 micron B+A-type disk fractions of 17/67 (25^+6^_-5_%), 36/131 (27^+4^_-5_%), and 23/95 (24^+5^_-4_%) for Upper Scorpius (~11Myr), Upper Centaurus Lupus (~15Myr), and Lower Centaurus Crux (~17Myr), respectively, somewhat smaller disk fractions than previously obtained for F- and G-type members. We confirm previous IRAS excess detections and present new discoveries of 51 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from LIR/L*=10^-6^ to 10^-2^ and grain temperatures ranging from Tgr=40 to 300K. In addition, we confirm that the 24 micron and 70 micron excesses (or fractional infrared luminosities) around B+A-type stars are smaller than those measured toward F+G-type stars and hypothesize that the observed disk property dependence on stellar mass may be the result of a higher stellar companion fraction around B- and A-type stars at 10-200AU. Finally, we note that the majority of the ScoCen 24 micron excess sources also possess 12 micron excess, indicating that Earth-like planets may be forming via collisions in the terrestrial planet zone at ~10-100Myr.
