- ID:
- ivo://CDS.VizieR/J/ApJS/240/16
- Title:
- Exoplanets in the Antarctic sky. I. AST3-II DR1
- Short Name:
- J/ApJS/240/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Located at Dome A, the highest point of the Antarctic plateau, the Chinese Kunlun station is considered to be one of the best ground-based photometric sites because of its extremely cold, dry, and stable atmosphere. A target can be monitored from there for over 40 days without diurnal interruption during a polar winter. This makes Kunlun station a perfect site to search for short- period transiting exoplanets. Since 2008, an observatory has existed at Kunlun station, and three telescopes are working there. Using these telescopes, the AST3 project has been carried out over the last 6yr with a search for transiting exoplanets as one of its key programs (CHinese Exoplanet Searching Program from Antarctica --CHESPA). In the austral winters of 2016 and 2017, a set of target fields in the southern continuous viewing zone (CVZ) of TESS were monitored by the AST3-II telescope. In this paper, we introduce the CHESPA and present the first data release containing photometry of 26,578 bright stars (m_i_<=15). The best photometric precision at the optimum magnitude for the survey is around 2 mmag. To demonstrate the data quality, we also present a catalog of 221 variables with a brightness variation greater than 5mmag from the 2016 data. Among these variables, 179 are newly identified periodic variables not listed in the AAVSO database (https://www.aavso.org/), and 67 are listed in the Candidate Target List. These variables will require careful attention to avoid false-positive signals when searching for transiting exoplanets.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/490/3806
- Title:
- Exoplanets & variable stars in 47 Tuc field
- Short Name:
- J/MNRAS/490/3806
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The TESS mission will survey ~85 per cent of the sky, giving us the opportunity of extracting high-precision light curves of millions of stars, including stellar cluster members. In this work, we present our project 'A PSF-based Approach to TESS High quality data Of Stellar clusters' (PATHOS), aimed at searching and characterize candidate exoplanets and variable stars in stellar clusters using our innovative method for the extraction of high-precision light curves of stars located in crowded environments. Our technique of light-curve extraction involves the use of empirical point spread functions (PSFs), an input catalogue and neighbour-subtraction. The PSF-based approach allows us to minimize the dilution effects in crowded environments and to extract high-precision photometry for stars in the faint regime (G>13). For this pilot project, we extracted, corrected, and analysed the light curves of 16641 stars located in a dense region centred on the globular cluster 47 Tuc. We were able to reach the TESS magnitude T~16.5 with a photometric precision of ~1 per cent on the 6.5-h time-scale; in the bright regime we were able to detect transits with depth of ~34 parts per million. We searched for variables and candidate transiting exoplanets. Our pipeline detected one planetary candidate orbiting a main-sequence star in the Galactic field. We analysed the period-luminosity distribution for red-giant stars of 47 Tuc and the eclipsing binaries in the field. Light curves are uploaded on the Mikulski Archive for Space Telescopes under the project PATHOS.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/32
- Title:
- Extended Aperture Photometry of K2 RR Lyrae stars
- Short Name:
- J/ApJS/244/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler Space Telescope observed thousands of RR Lyrae stars in the K2 mission. In this paper, we present our photometric solutions using extended apertures in order to conserve the flux of the stars to the highest possible extent. With this method, we are able to avoid most of the problems that RR Lyrae light curves produced by other pipelines suffer from. For post-processing, we apply the K2SC pipeline to our light curves. We provide the EAP (Extended Aperture Photometry) of 432 RR Lyrae stars observed in campaigns 3, 4, 5, and 6. We also provide subclass classifications based on Fourier parameters. We investigated in particular the presence of the Blazhko effect in the stars and found it to be 44.7% among the RRab stars, in agreement with results from independent samples. We found that the amplitude and phase modulation in the Blazhko stars may behave rather differently, at least over the length of a K2 Campaign. We also identified four anomalous Cepheid candidates in the sample, one of which is potentially the first Blazhko-modulated member of its class.
- ID:
- ivo://CDS.VizieR/J/other/OEJV/87
- Title:
- Extended catalog of NSVS red AGB variable stars
- Short Name:
- J/other/OEJV/87
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In this paper we present the catalog of new Mira-type and SR+L variable stars in the Northern Sky Variability Survey (NSVS) database, found after complementing the original NSVS object tables with a number of additional parameters. By extending the amount of criteria search queries can take advantage of and filtering known objects out, it became convenient to apply better constrained filters to search new variable star candidates. As an example of presented approach, the quest for red variables has resulted in 78 Mira-type and 717 SR+L stars found that have no identification in General Catalogue of Variable Stars, SIMBAD and VSX databases. Most likely the stars presented are new discoveries. The classification of these stars is based on the near-infrared colors from Two Micron All Sky Survey (2MASS) photometry, amplitude and period with the accuracy of the classification given ~90%, estimated basing on the current GCVS classification scheme.
- ID:
- ivo://CDS.VizieR/J/other/IBVS/5296
- Title:
- Extrema of pulsating stars
- Short Name:
- J/other/IBVS/529
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this 46th compilation of BAV results, photoelectric observations obtained in the years 2000 till 2002 are presented on 428 variable stars giving 843 minima and maxima. All moments of minima and maxima are heliocentric. The values in column 'O-C' are determined without incorporation of nonlinear terms. The references are given in the section 'Remarks'. All information about photometers and filters are specified in the column 'Rem'. The observations were made at private observatories. The photoelectric measurements and all the lightcurves with evaluations can be obtained from the office of the BAV for inspection.
- ID:
- ivo://archive.stsci.edu/euve
- Title:
- Extreme Ultraviolet Explorer
- Short Name:
- EUVE
- Date:
- 22 Jul 2020 21:28:51
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- Launched in June, 1992, The Extreme Ultraviolet Explorer (EUVE) conducted the first extreme ultraviolet (70-760 Angstroms) survey of the sky and subsequently began a Guest Observer Program of pointed
- ID:
- ivo://CDS.VizieR/J/A+A/642/A225
- Title:
- Faculae-Spot dominance & rotation periods
- Short Name:
- J/A+A/642/A225
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar rotation periods can be determined by observing brightness variations caused by active magnetic regions transiting visible stellar disk as the star rotates. The successful stellar photometric surveys stemming from the Kepler and TESS observations led to the determination of rotation periods in tens of thousands of young and active stars. However, there is still a lack of information about rotation periods of older and less active stars, like the Sun. The irregular temporal profiles of light curves caused by the decay times of active regions, which are comparable to or even shorter than stellar rotation periods, combine with the random emergence of active regions to make period determination for such stars very difficult. We tested the performance of the new method for the determination of stellar rotation periods against stars with previously determined rotation periods. The method is based on calculating the gradient of the power spectrum (GPS) and identifying the position of the inflection point (i.e. point with the highest gradient). The GPS method is specifically aimed at determining rotation periods of low-activity stars like the Sun. We applied the GPS method to Sun-like stars observed by the Kepler telescope. We separately considered two stellar samples: one with near-solar rotation periods (24-27.4d) and broad range of effective temperatures (5000-6000K), another with near-solar effective temperatures (5700-5900K) and broad range of rotation periods (15-40d). We show that the GPS method returns precise values of stellar rotation periods. Furthermore, it allows us to constrain the ratio between facular and spot areas of active regions at the moment of their emergence. We show that relative facular area decreases with stellar rotation rate. Our results suggest that the GPS method can be successfully applied to retrieve periods of stars with both regular and non-regular light curves.
- ID:
- ivo://archive.stsci.edu/fuse
- Title:
- Far Ultraviolet Spectroscopic Explorer
- Short Name:
- FUSE
- Date:
- 22 Jul 2020 21:29:31
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- The Far Ultraviolet Spectroscopic Explorer (FUSE), launched on June 24, 1999, covers the 905-1187 Å spectral region and will obtain high resolution spectra of hot and cool stars, AGNs, supernova remnants, planetary nebulae, solar system objects as well as perform detailed studies of the interstellar medium. FUSE will be able to observe sources 10 000 times fainter than Copernicus, an early FUV mission, and has superior resolving power than the Hopkins Ultraviolet Telescope (HUT) and the Berkeley Spectrograph (BEFS) and the Tübingen Echelle Spectrograph (TUES) of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometers (ORFEUS). FUSE was planned for a 3 year lifetime with funding for an additional 2 years expected.
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1205
- Title:
- Fast transients in the Fornax cluster
- Short Name:
- J/ApJ/682/1205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity gap between novae (M_R_<=-10) and supernovae (M_R_>=-14) has been well known since the pioneering research of Zwicky and Hubble. Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae. Here we present the results of a B-band survey of 23 member galaxies of the Fornax Cluster, performed at the Las Campanas 2.5m Irenee du Pont telescope. Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of M_B_=-9.3mag. We provide a detailed assessment of the transient detection efficiency and the resulting upper limits on the event rate as function of peak magnitude. Further, we discuss the discoveries of five previously unknown foreground variables which we identified as two flare stars, two W UMa-type eclipsing binaries and a candidate {delta} Scuti/SX Phe star.
- ID:
- ivo://CDS.VizieR/J/A+A/312/111
- Title:
- [Fe/H] from RR Lyrae light curves
- Short Name:
- J/A+A/312/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an accurate and robust method for the calculation of [Fe/H] from the light curves of RRab stars. The method introduces a considerable improvement relative to our previously published formulae. First of all, it uses an improved and extended data base for the light curves and more accurate, very recent iron abundances. Secondly, the new data base makes it possible to show that the basic relation between [Fe/H] and the Fourier parameters is linear and contains only the period and one of the Fourier phases, most importantly {phi}_31_. Last but not least, we derive interrelations among the Fourier parameters which help us to filter out peculiar stars where more caution is needed in accepting the calculated abundance. The applicability of the method is demonstrated on independent samples of globular cluster stars. Peculiarities encountered in Blazhko variables and in some other cases are also discussed. The Fourier decomposition is defined by the formula: V(t) = A0 + A1*sin(2*pi/P*(t-t0)+phi1) + A2*sin(2*pi*2/P*(t-t0)+phi2) +... + A15*sin(2*pi*15/P*(t-t0)+phi15) V(t) -- light curve in Johnson V P -- period t0 -- Epoch = 2400000.0
