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- ID:
- ivo://CDS.VizieR/J/other/NewA/32.6
- Title:
- BP Peg times of maximum light
- Short Name:
- J/other/NewA/32.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD photometric monitoring on the high-amplitude delta Scuti variable BP Peg was carried out on November 4, 2013 by using the 1.0-m reflecting telescope of Yunnan Observatories in China as well as on December 29, 2013 by using the 85-cm telescope at Xinglong Station of National Astronomical Observatory in China. BP Peg is a new high-amplitude delta Scuti variable with a period of 0.10954357-day. We have collected all the times of light maximum from the literature together with our data, and the pulsation period changes are analyzed through Observed-Calculated (O-C) method. With the available data, we discover that the pulsating period of BP Peg shows a cyclic oscillation with a period of 24.5-years and an amplitude of 0.0060-days. If the cyclic period changes are caused by light-time effect in a binary system, the reckoned mass of the hidden companion could be 0.20M_{sun}_ and possibly, it is an M-type star.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A1
- Title:
- Bright B-type variables in Scorpius
- Short Name:
- J/A+A/557/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first two of a total of six nano-satellites that will constitute the BRITE-Constellation space photometry mission have recently been launched successfully. In preparation for this project, we carried out time-resolved colour photometry in a field that is an excellent candidate for BRITE measurements from space. We acquired 117h of Stromgren uvy data during 19 nights. Our targets comprised the {beta} Cephei stars {kappa} and {lambda} Sco, the eclipsing binary {mu}^1^ Sco, and the variable super/hypergiant {zeta}^1^ Sco. For {kappa} Sco, a photometric mode identification in combination with results from the spectroscopic literature suggests a dominant (l,m)=(1,-1) {beta} Cephei-type pulsation mode of the primary star. The longer period of the star may be a rotational variation or a g-mode pulsation. For {lambda} Sco, we recover the known dominant {beta} Cephei pulsation, a longer-period variation, and observed part of an eclipse. Lack of ultraviolet data precludes mode identification for this star. We noticed that the spectroscopic orbital ephemeris of the closer pair in this triple system is inconsistent with eclipse timings and propose a refined value for the orbital period of the closer pair of 5.95189+/-0.00003d. We also argue that the components of the {lambda} Sco system are some 30% more massive than previously thought. The binary light curve solution of {mu}^1^ Sco requires inclusion of the irradiation effect to explain the u light curve, and the system could show additional low amplitude variations on top of the orbital light changes. {zeta}^1^ Sco shows long-term variability on a time scale of at least two weeks that we prefer to interpret in terms of a variable wind or strange mode pulsations.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A111
- Title:
- Brown dwarf atmosphere monitoring (BAM)
- Short Name:
- J/A+A/566/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the SofI instrument on the 3.5m New Technology Telescope, we have conducted an extensive near-infrared monitoring survey of an unbiased sample of 69 brown dwarfs spanning the L0 to T8 spectral range, with at least one example of each spectral type. Each target was observed for a 2-4 hour period in the Js-band, and the median photometric precision of the data is ~0.7%. A total of 14 brown dwarfs were identified as variables with min-to-max amplitudes ranging from 1.7% to 10.8% over the observed duration. All variables satisfy a statistical significance threshold with a p-value <=5% based on comparison with a median reference star light curve. Approximately half of the variables show pure sinusoidal amplitude variations similar to 2MASSJ2139+0220, and the remainder show multi-component variability in their light curves similar to SIMPJ0136+0933.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/L25
- Title:
- Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR)
- Short Name:
- J/ApJ/821/L25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars (RRLs) exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RRLs predate these structures and have metallicities, kinematics, and spatial distribution that are consistent with a "classical" bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal-rich ([Fe/H]~-1dex) halo-bulge population.
- ID:
- ivo://CDS.VizieR/J/other/ApSS/363.127
- Title:
- Bulge RR Lyrae VVVDR4 photometry
- Short Name:
- J/other/ApSS/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study's objective was to exploit infrared VVV (VISTA Variables in the Via Lactea) photometry for high latitude RRab stars to establish an accurate Galactic Centre distance. RRab candidates were discovered and reaffirmed (n=4194) by matching Ks photometry with templates via chisq minimization, and contaminants were reduced by ensuring targets adhered to a strict period-amplitude (Ks) trend and passed the Elorietta et al. (2016A&A...595A..82E) classifier. The distance to the Galactic Centre was determined from a high latitude Bulge subsample (|b|>4, RGC=8.30+/-0.36kpc, random uncertainty is relatively negligible), and importantly, the comparatively low color-excess and uncrowded location mitigated uncertainties tied to the extinction law, the magnitude-limited nature of the analysis, and photometric contamination. Circumventing those problems resulted in a key uncertainty being the MKs relation, which was derived using LMC RRab stars (MKs=-(2.66+/-0.06)logP-(1.03+/-0.06), (J-Ks)0=(0.31+/-0.04)logP +(0.35+/-0.02), assuming mu0LMC=18.43). The Galactic Centre distance was not corrected for the cone-effect. Lastly, a new distance indicator emerged as brighter overdensities in the period-magnitude-amplitude diagrams analyzed, which arise from blended RRab and red clump stars. Blending may thrust faint extragalactic variables into the range of detectability.
- ID:
- ivo://CDS.VizieR/J/A+A/344/263
- Title:
- B-V colour excess of Miras
- Short Name:
- J/A+A/344/263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A study of 73 carbon-rich Miras (see Subsec. 6.1) with suitable solution for 56 stars at one or several phase of their variations. In the second part, preliminary and incomplete results are reported for 17 additional Miras observed at only one phase. Table 5 contains our HC-CV-classification (see text) for the stars and their colour excess E(B-V) as determined by the method described in Subsec. 2.2.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1421
- Title:
- BV differential photometry of 11 gamma Dor stars
- Short Name:
- J/AJ/133/1421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used precise photometric and high-dispersion spectroscopic observations to study 11 gamma Doradus stars, 10 of them newly confirmed. Only five of these 11 gamma Doradus stars appear to be single; two are primaries of double-lined spectroscopic binaries, one is the secondary of a double-lined binary, two are primaries of visual binaries and, in the case of the double-lined binary (HD 86371), either or both components could be a pulsating gamma Doradus star. We have determined a preliminary orbital period of 5.32 days for the double-lined binary HD 41547. Several of the stars show spectroscopic line-profile and low-amplitude radial velocity variability indicative of pulsation. All 11 stars are photometrically variable with amplitudes between 4 and 94 mmag in Johnson B and periods between 0.38 and 1.86 days. The 11 stars have between two and five independent periods.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A36
- Title:
- BV differential photometry of V711 Tau
- Short Name:
- J/A+A/521/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We attempt to establish the real nature of the orbital period variation and its relation to the spot activity of V711 Tau, and determine why the (B-V) colour of the star appears to be nearly independent of its V magnitude. We wish to verify whether existing predictions in the literature for the long-term spot activity of the star are true or not by making extended photometric observations, and whether the broad component of H{alpha} emission originates in more localised active regions, as suggested by some chromospheric models, by searching for any correlation between the base-line width of the emission and the light modulation.
- ID:
- ivo://CDS.VizieR/J/A+A/465/943
- Title:
- BVI and RV curves of 5 eclipsing binaries
- Short Name:
- J/A+A/465/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters. We carried out new photometric and spectroscopic observations of five bright close eclipsing binaries, predominantly in the southern skies. We obtained full Johnson BV light curves, which were modelled with the Wilson-Devinney code. Radial velocities were measured with the cross-correlation method using IAU radial velocity standards as spectral templates. Period changes were studied with the O-C method, utilising published epochs of minimum light (XY Leo) and ASAS photometry (VZ Lib). For three objects (DX Tuc, QY Hya, V870 Ara), absolute parameters have been determined for the first time. We spectroscopically detected the tertiary components in XY Leo and VZ Lib and discovered one in QY Hya. For XY Leo we updated the light-time effect parameters and detected a secondary periodicity of about 5100d in the O-C diagram that may hint at the existence of short-period magnetic cycles. A combination of recent photometric data shows that the orbital period of the tertiary star in VZ Lib is likely to be over 1500d. QY Hya is a semi-detached X-ray active binary in a triple system with K and M-type components, while V870 Ara is a contact binary with the third smallest spectroscopic mass ratio for a W UMa star to date. Being close to the theoretical minimum for contact binaries, this small mass ratio suggests that V870 Ara has the potential of constraining evolutionary scenarios of binary mergers. The inferred distances to these systems are compatible with the Hipparcos parallaxes.