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781. R light curves of NGC 6253 variables
ID:
ivo://CDS.VizieR/J/A+A/509/A17
Title:
R light curves of NGC 6253 variables
Short Name:
J/A+A/509/A17
Date:
21 Oct 2021
Publisher:
CDS
Description:
This work presents the first high-precision variability survey in the field of the intermediate-age, metal-rich open cluster NGC 6253. We discovered 595 variables and we also characterized most of them providing their variability classes, periods and amplitudes. The sample is complete at short periods: we classified 20 pulsating variables, 225 contact systems, 99 eclipsing systems (22 Beta Lyr type, 59 Beta Per type, 18 RS CVn type), and 77 rotational variables. The time-baseline hampered the precise characterization of 173 variables with periods longer than 4-5days. Moreover, we found a cataclysmic system undergoing an outburst of about 2.5mag.
782. RMC143 ALMA images
ID:
ivo://CDS.VizieR/J/A+A/626/A126
Title:
RMC143 ALMA images
Short Name:
J/A+A/626/A126
Date:
21 Oct 2021
Publisher:
CDS
Description:
The luminous blue variable (LBV) RMC143 is located in the outskirts of the 30~Doradus complex, a region rich with interstellar material and hot luminous stars. We report the 3{sigma} sub-millimetre detection of its circumstellar nebula with ALMA. The observed morphology in the sub-millimetre is different than previously observed with HST and ATCA in the optical and centimetre wavelength regimes. The spectral energy distribution (SED) of RMC suggests that two emission mechanisms contribute to the sub-mm emission: optically thin bremsstrahlung and dust. Both the extinction map and the SED are consistent with a dusty massive nebula with a dust mass of 0.055+/-0.018M_{sun}_ (assuming {kappa}_850_=1.7cm^2^/g). To date, RMC143 has the most dusty LBV nebula observed in the Magellanic Clouds. We have also re-examined the LBV classification of RMC143 based on VLT/X-shooter spectra obtained in 2015/16 and a review of the publication record. The radiative transfer code CMFGEN is used to derive its fundamental stellar parameters. We find an effective temperature of ~8500K, luminosity of log(L/L_{sun}_)=5.32, and a relatively high mass-loss rate of 1.0x10^-5^M_{sun}_/yr. The luminosity is much lower than previously thought, which implies that the current stellar mass of ~8M_{sun}_ is comparable to its nebular mass of ~5.5~M_{sun}_ (from an assumed gas-to-dust ratio of 100), suggesting that the star has lost a large fraction of its initial mass in past LBV eruptions or binary interactions. While the star may have been hotter in the past, it is currently not hot enough to ionize its circumstellar nebula. We propose that the nebula is ionized externally by the hot stars in the 30 Doradus star-forming region.
783. Rosino-Guzzi variables in Sagitta
ID:
ivo://CDS.VizieR/J/other/IBVS/4433
Title:
Rosino-Guzzi variables in Sagitta
Short Name:
J/other/IBVS/443
Date:
21 Oct 2021
Publisher:
CDS
Description:
The list below gives accurate coordinates and IRAS identifications for all but one of the 123 red variable stars found by Rosino & Guzzi (1978A&AS...31..313R)) on a series of infrared plates.
784. Rotational periods in Cygnus OB2
ID:
ivo://CDS.VizieR/J/A+A/603/A106
Title:
Rotational periods in Cygnus OB2
Short Name:
J/A+A/603/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a near-infrared time-series photometry study in the field of Cygnus OB2 association (RA~20.55h, DE~41.2{deg}). Observations were carried out in the JHK bands at the WFCAM/UKIRT telescope over 112 observed nights. We investigated the occurrence of periodicity in the time-series and we found reliable periods for 894 candidate members.
785. Rotational properties of mCP stars
ID:
ivo://CDS.VizieR/J/MNRAS/468/2745
Title:
Rotational properties of mCP stars
Short Name:
J/MNRAS/468/2745
Date:
21 Oct 2021
Publisher:
CDS
Description:
The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit strong, globally organized magnetic fields that are inclined to the rotational axis and facilitate the development of surface abundance inhomogeneities resulting in photometric and spectroscopic variability. Therefore, mCP stars are perfectly suited for a direct measurement of the rotational period without the need for any additional calibrations. We have investigated the rotational properties of mCP stars based on an unprecedentedly large sample consisting of more than 500 objects with known rotational periods. Using precise parallaxes from the Hipparcos and Gaia satellite missions, well-established photometric calibrations and state-of-the-art evolutionary models, we have determined the location of our sample stars in the Hertzsprung-Russell diagram and derived astrophysical parameters such as stellar masses, effective temperature, radii, inclinations and critical rotational velocities. We have confirmed the conservation of angular momentum during the main sequence evolution; no signs of additional magnetic braking were found. The inclination angles of the rotational axes are randomly distributed, although an apparent excess of fast rotators with comparable inclination angles has been observed. We have found a rotation rate of v/v_crit_>=0.5 for several stars, whose characteristics cannot be explained by current models. For the first time, we have derived the relationship between mass and rotation rate of mCP stars, and provide an analysis that links mass and rotation with magnetic field strength. Our sample is unique and offers crucial input for forthcoming evolutionary models that include the effects of magnetic fields for upper main sequence stars.
786. Rotation and variability of substellar objects
ID:
ivo://CDS.VizieR/J/A+A/566/A130
Title:
Rotation and variability of substellar objects
Short Name:
J/A+A/566/A130
Date:
21 Oct 2021
Publisher:
CDS
Description:
Doppler Imaging produces 2D global maps of rotating objects using high-dispersion spectroscopy. When applied to brown dwarfs and extrasolar planets, this technique can constrain global atmospheric dynamics and/or magnetic effects on these objects in un- precedented detail. I present the first quantitative assessment of the prospects for Doppler Imaging of substellar objects with current facilities and with future giant ground-based telescopes. Observations will have the greatest sensitivity in K band, but the H and L bands will also be useful for these purposes. To assess the number and availability of targets, I also present a compilation of all measurements of photometric variability, rotation period (P), and projected rotational velocity (vsini) for brown dwarfs and exoplanets. Several bright objects are already accessible to Doppler Imaging with currently available instruments. With the development of giant ground-based telescopes, Doppler Imaging will become feasible for many dozens of brown dwarfs and for the few brightest directly imaged extrasolar planets (such as beta Pic b). The present set of measurements of P, vsini, and variability are incomplete for many objects, and the sample is strongly biased toward early-type objects (<L5). Thus, surveys to measure these quantities for later-type objects will be especially helpful in expanding the sample of candidates for global weather monitoring via Doppler Imaging.
787. Rotation of field stars from CoRoT data
ID:
ivo://CDS.VizieR/J/MNRAS/424/11
Title:
Rotation of field stars from CoRoT data
Short Name:
J/MNRAS/424/11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present period measurements of a large sample of field stars in the solar neighbourhood, observed by the COnvection ROtation and planetary Transits (CoRoT) satellite in two different directions of the Galaxy. The presence of a period was detected using the Lomb-Scargle normalized periodogram technique and the autocorrelation analysis. The assessment of the results has been performed through a consistency verification supported by the folded light-curve analysis. The data analysis procedure has discarded a non-negligible fraction of light curves due to instrumental artefacts; however, it has allowed us to identify pulsators and binaries among a large number of field stars. We measure a wide range of periods, from 0.25 to 100d, most of which are rotation periods. The final catalogue includes 1978 periods, with 1727 of them identified as rotational periods, 169 as pulsations and 82 as orbital periods of binary systems.
788. Rotation periods for NGC 3532
ID:
ivo://CDS.VizieR/J/A+A/652/A60
Title:
Rotation periods for NGC 3532
Short Name:
J/A+A/652/A60
Date:
22 Feb 2022
Publisher:
CDS
Description:
A very rich cluster intermediate in age between the Pleiades (150Myr) and the Hyades (600Myr) is needed to probe the rotational evolution, especially the transition between fast and slow rotation that occurs between the two ages. We study the rich 300Myr-old open cluster NGC 3532 to probe this important transition and to provide constraints on angular momentum loss. Measuring the rotation periods builds on our prior work of providing spectroscopic membership information for the cluster, and it supports the chromospheric activity measurements of cluster stars that we provide in a companion paper. Using 42d-long photometric time series observations obtained with the Yale 1m telescope at CTIO, we measured rotation periods for members of NGC 3532 and compared them with the predictions of angular momentum evolution models. We directly measured 176 photometric rotation periods for the cluster members. An additional 113 photometric rotation periods were identified using activity information, described fully in the companion paper, resulting in a total sample containing 279 rotation periods for FGKM stars in NGC 3532. The colour-period diagram constructed from this rich data set shows a well-populated and structured slow rotator sequence, and a fast rotator sequence evolved beyond zero-age main sequence age whose stars are in transition from fast to slow rotation. The slow rotator sequence itself is split into slightly slower and faster rotators, a feature we trace to photometric binary status. We also identify an extended slow rotator sequence extending to P~32d, apparently the analogue of the one we previously identified in NGC 2516. We compare our period distribution to rotational isochrones in colour-period space and find that all considered models have certain shortcomings. Using more detailed spin-down models, we evolve the rotation periods of the younger NGC 2516 forward in time and find that the spindown of the models is too aggressive with respect to the slow rotators. In contrast, stars on the evolved fast rotator sequence are not spun down strongly enough by these models. Our observations suggest a shorter crossing time for the rotational gap, one we estimate to be ~80Myr for early-K dwarfs.
789. Rotation periods of active Kepler stars
ID:
ivo://CDS.VizieR/J/A+A/560/A4
Title:
Rotation periods of active Kepler stars
Short Name:
J/A+A/560/A4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present rotation periods for thousands of active stars in the Kepler field derived from Q3 data. In most cases a second period close to the rotation period was detected, which we interpreted as surface differential rotation (DR).
790. ROTSE all-sky surveys for variable stars
ID:
ivo://CDS.VizieR/J/AJ/119/1901
Title:
ROTSE all-sky surveys for variable stars
Short Name:
J/AJ/119/1901
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Robotic Optical Transient Search Experiment I (ROTSE-I) experiment has generated CCD photometry for the entire northern sky in two epochs nightly since 1998 March. These sky patrol data are a powerful resource for studies of astrophysical transients. As a demonstration project, we present first results of a search for periodic variable stars derived from ROTSE-I observations. Variable identification, period determination, and type classification are conducted via automatic algorithms. In a set of nine ROTSE-I sky patrol fields covering roughly 2000 deg^2^, we identify 1781 periodic variable stars with mean magnitudes between m_v_ = 10.0 and m_v_ = 15.5. About 90% of these objects are newly identified as variable. Examples of many familiar types are presented. All classifications for this study have been manually confirmed. The selection criteria for this analysis have been conservatively defined and are known to be biased against some variable classes. This preliminary study includes only 5.6% of the total ROTSE-I sky coverage, suggesting that the full ROTSE-I variable catalog will include more than 32,000 periodic variable stars.