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1. AAVSO Photometric All Sky Survey (APASS) DR9
ID:
ivo://CDS.VizieR/II/336
Title:
AAVSO Photometric All Sky Survey (APASS) DR9
Short Name:
II/336
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AAVSO Photometric All Sky Survey (APASS) project is designed to bridge the gap between the shallow Tycho2 two-bandpass photometric catalog that is complete to V=11 and the deeper, but less spatially-complete catalogs like SDSS or PanSTARRS. It can be used for calibration of a specific field; for obtaining spectral information about single sources, determining reddening in a small area of the sky; or even obtaining current-epoch astrometry for rapidly moving objects. The survey is being performed at two locations: near Weed, New Mexico in the Northern Hemisphere; and at CTIO in the Southern Hemisphere. Each site consists of dual bore-sighted 20cm telescopes on a single mount, designed to obtain two bandpasses of information simultaneously. Each telescope covers 9 square degrees of sky with 2.5arcsec pixels, with the main survey taken with B,V,g',r',i' filters and covering the magnitude range 10<V<17. A bright extension is underway, saturating at V=7 and extending the wavelength coverage from u' to Y. The current catalog is Data Release 9 and contains approximately 62 million stars. The American Association of Variable Star Observers is responsible for the overall management of the survey; a team of professional astronomers participate in the data analysis. The project was initially funded by the Robert Martin Ayers Sciences Fund, with a follow-on grant from the National Science Foundation.
2. ACS VI photometry of M31 halo RR Lyrea
ID:
ivo://CDS.VizieR/J/AJ/127/2738
Title:
ACS VI photometry of M31 halo RR Lyrea
Short Name:
J/AJ/127/2738
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a complete census of RR Lyrae stars in a halo field of the Andromeda galaxy. These deep observations, taken as part of a program to measure the star formation history in the halo, spanned a period of 41 days with sampling on a variety of timescales, enabling the identification of short- and long-period variables. Although the long-period variables cannot be fully characterized within the time span of this program, the enormous advance in sensitivity provided by the Advanced Camera for Surveys on the Hubble Space Telescope allows accurate characterization of the RR Lyrae population in this field. We find 29 RRab stars with a mean period of 0.594 days, 25 RRc stars with a mean period of 0.316 days, and one RRd star with a fundamental period of 0.473 days and a first-overtone period of 0.353 days. These 55 RR Lyrae stars imply a specific frequency S_RR_~5.6, which is large given the high mean metallicity of the halo, but not surprising given that these stars arise from the old, metal-poor tail of the distribution.
3. Activity cycles in 3203 Kepler stars
ID:
ivo://CDS.VizieR/J/A+A/603/A52
Title:
Activity cycles in 3203 Kepler stars
Short Name:
J/A+A/603/A52
Date:
21 Oct 2021
Publisher:
CDS
Description:
In recent years it has been claimed that the length of stellar activity cycles is determined by the stellar rotation rate. It has been observed that the cycle period increases with rotation period along two distinct sequences, known as the active and inactive sequences. In this picture the Sun occupies a solitary position between the two sequences. Whether the Sun might undergo a transitional evolutionary stage is currently under debate. Our goal is to measure cyclic variations of the stellar light curve amplitude and the rotation period using four years of Kepler data. Periodic changes in the light curve amplitude or the stellar rotation period are associated with an underlying activity cycle. Using a recent sample of active stars we compute the rotation period and the variability amplitude for each individual Kepler quarter and search for periodic variations of both time series. To test for periodicity in each stellar time series we consider Lomb-Scargle periodograms and use a selection based on a false alarm probability (FAP). We detect amplitude periodicities in 3203 stars between 0.5-6 years covering rotation periods between 1-40 days. Given our sample size of 23,601 stars and our selection criteria that the FAP is less than 5%, this number is almost three times higher than that expected from pure noise. We do not detect periodicities in the rotation period beyond those expected from noise. Our measurements reveal that the cycle period shows a weak dependence on rotation rate, slightly increasing for longer rotation periods. We further show that the shape of the variability deviates from a pure sine curve, consistent with observations of the solar cycle. The cycle shape does not show a statistically significant dependence on effective temperature. We detect activity cycles in more than 13% of our final sample with a FAP of 5% (calculated by randomly shuffling the measured 90-day variability measurements for each star). Our measurements do not support the existence of distinct sequences in the Prot-Pcyc plane, although there is some evidence for the inactive sequence for rotation periods between 5-25 days. Unfortunately,the total observing time is too short to draw sound conclusions on activity cycles with similar lengths to that of the solar cycle.
4. A first catalog of variable stars measured by ATLAS
ID:
ivo://CDS.VizieR/J/AJ/156/241
Title:
A first catalog of variable stars measured by ATLAS
Short Name:
J/AJ/156/241
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Asteroid Terrestrial-impact Last Alert System (ATLAS) carries out its primary planetary defense mission by surveying about 13000 deg^2^ at least four times per night. The resulting data set is useful for the discovery of variable stars to a magnitude limit fainter than r~18, with amplitudes down to 0.02 mag for bright objects. Here, we present a Data Release One catalog of variable stars based on analyzing the light curves of 142 million stars that were measured at least 100 times in the first two years of ATLAS operations. Using a Lomb-Scargle periodogram and other variability metrics, we identify 4.7 million candidate variables. Through the Space Telescope Science Institute, we publicly release light curves for all of them, together with a vector of 169 classification features for each star. We do this at the level of unconfirmed candidate variables in order to provide the community with a large set of homogeneously analyzed photometry and to avoid pre-judging which types of objects others may find most interesting. We use machine learning to classify the candidates into 15 different broad categories based on light-curve morphology. About 10% (427000 stars) pass extensive tests designed to screen out spurious variability detections: we label these as "probable" variables. Of these, 214000 receive specific classifications as eclipsing binaries, pulsating, Mira-type, or sinusoidal variables: these are the "classified" variables. New discoveries among the probable variables number 315000, while 141000 of the classified variables are new, including about 10400 pulsating variables, 2060 Mira stars, and 74700 eclipsing binaries.
5. AGAPE catalogue of M31 variables
ID:
ivo://CDS.VizieR/J/A+A/421/509
Title:
AGAPE catalogue of M31 variables
Short Name:
J/A+A/421/509
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the AGAPE astrometric and photometric catalogue of 1579 variable stars in a 14' x 10' field centred on M31. Each variable star in the catalogue is identified as AGPVm, m running from 1 to 1579. Then are given: Fn(x,y) (F being the letter of identification of AGAPE field and n the variable star number in this field; x and y being the pixel coordinates in the reference frame), right ascension and declination for 2000.0, R_max_ magnitude at observed maximum, and L the likelihood function. When the variable star is a nova discovered by eye, no L value is given.
6. AGAPEROS: variable stars in the LMC Bar
ID:
ivo://CDS.VizieR/J/A+AS/145/11
Title:
AGAPEROS: variable stars in the LMC Bar
Short Name:
J/A+AS/145/11
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 91-92 EROS-1 data set has been used to select Long Timescale and Long Period Variables (LT&LPV). We choose to perform a selection of variable objects as comprehensive as possible, independent of periodicity and of their position on the colour magnitude diagram, and produce a catalogue of 632 variable objects. Table 2 provides the parameters of the variable objects detected in this paper. They are sorted in order of increasing right ascension. The columns contains the name of the variable including the RA,DEC (J2000.0) coordinates, the number of the chip and (x,y) position, the blending flags (PhiC/Phi0)_B_, (PhiC/Phi0)_R_ in both colours, the B_EROS_ and R_EROS_ magnitude, the number of star N_star_B, N_star_R found in the superpixel, the magnitude B_EROS_DAO and R_EROS_DAO estimated with DAOPHOT, and when available the cross-identifications with previous catalogue.
7. AH Cam
ID:
ivo://CDS.VizieR/J/AJ/107/679
Title:
AH Cam
Short Name:
J/AJ/107/679
Date:
21 Oct 2021
Publisher:
CDS
Description:
Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989-1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686d and an apparent secondary period of 0.2628d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with {DELTA}S<=2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental mode vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.
8. AI CMi UBV light curves
ID:
ivo://CDS.VizieR/J/PAZh/43/460
Title:
AI CMi UBV light curves
Short Name:
J/PAZh/43/460
Date:
21 Oct 2021
Publisher:
CDS
Description:
The U BV photometry and low-resolution spectroscopy for the semiregular variable AI CMi, a candidate for post-AGB objects, performed in 1996-2016 and 2000-2013, respectively, are presented. The star showed multiperiodic brightness variations with an amplitude up to 1.5m in the V band, a significant (up to 0.4m) bluing of the B-V and U-B colors as the star faded, and a change of its spectrum from G5 I to K3-5 I, depending on its brightness. A possible long-term fading of AI CMi below 8.5m in the period from May 2013 to early 2015 is observed in the light curve. The colors in this episode did not change the pattern of their unusual behavior with brightness. The main feature of the spectrum for AI CMi is the appearance and strengthening of TiO absorption bands as its brightness declines, which are atypical in the spectra of ordinary G5-K3 supergiants. The bluing of the B-V and U-B colors is interpreted as the blanketing of stellar radiation predominantly in V (and to a lesser extent in B) by the TiO absorption bands whose intensity increases dramatically with decreasing brightness. Another cause of the bluing can be the scattering of stellar radiation by small dust particles in the gas-dust shell of AI CMi. The star's continuum-normalized spectra over the period from 2000 to 2013 in the wavelength range 4200 to 7700 or 9200{AA} are presented. These were taken at different phases of the pulsation cycle and clearly demonstrate the behavior of the TiO absorption bands depending on the V magnitude and B-V color. The equivalent widths of individual TiO bands were measured, and their correlation with the photometric parameters of the star is shown. AI CMi belongs to the O-rich branch of AGB/post-AGB supergiants and has a luminosity of ~4000L_{sun}_ at a distance of 1500+/-700pc. The mass of AI CMi is most likely small and close to the lower mass limit for post-AGB stars. The connection of the star's pulsational activity and nonstationary wind with the formation of its molecular and dust shells is discussed briefly.
9. AKARI observations of SMC Cepheids
ID:
ivo://CDS.VizieR/J/MNRAS/420/585
Title:
AKARI observations of SMC Cepheids
Short Name:
J/MNRAS/420/585
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work we matched the AKARI archival data to the Optical Gravitational Lensing Experiment III (OGLE-III) catalogue to derive the mid-infrared period-luminosity (PL) relations for Small Magellanic Cloud (SMC) Cepheids. Mismatched AKARI sources were eliminated using random-phase colours obtained from the full I-band light curves from OGLE-III. It was possible to derive PL relations in the N3 and N4 bands only, although the S7-, S11-, L15- and L24-band data were also tested. Random-phase correction was included when deriving the PL relation in the N3 and N4 bands using the available time of observations from AKARI data. The final adopted PL relations were N3=-3.370logP+16.527 and N4=-3.402logP+16.556. However, these PL relations may be biased due to the small number of Cepheids in the sample.
10. Algol-type binaries. IX. V548 Cyg
ID:
ivo://CDS.VizieR/J/AJ/152/49
Title:
Algol-type binaries. IX. V548 Cyg
Short Name:
J/AJ/152/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new UV light curve of the Algol eclipsing binary V548 Cyg obtained with the Lunar Ultraviolet Telescope. We model the UV light curve together with two previously published (B and V) light curves, primary star radial velocities, and eclipse timings in a unified multi-data-type solution and determine orbital parameters and absolute dimensions. Timing residuals hint at the presence of a third star in the system. This star is possibly the source of the third light that is needed to obtain a good fit to each of the light curves simultaneously. The light-time oscillation in the timing residuals has a period of either ~19 or ~46years. The third body orbit inclination would have to be low (23{deg} or 15{deg}, respectively) for the third star to have a mass of ~1.5M_{Sun}_, which would be expected for a main-sequence star of color B-V~0.32, as determined from the light curve solution. In an H-R diagram, the mass-gaining, primary component of V548 Cyg is located between the zero-age and terminal-age main sequence for solar composition stars, and close to the 0.4Gyr isochrone.

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