- ID:
- ivo://CDS.VizieR/J/ApJ/822/81
- Title:
- PTF stellar rotation periods for Pleiades members
- Short Name:
- J/ApJ/822/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar rotation periods (P_rot_) measured in open clusters have proved to be extremely useful for studying stars' angular momentum content and rotationally driven magnetic activity, which are both age- and mass-dependent processes. While P_rot_ measurements have been obtained for hundreds of solar-mass members of the Pleiades, measurements exist for only a few low-mass (<0.5 M_{sun}_) members of this key laboratory for stellar evolution theory. To fill this gap, we report P_rot_ for 132 low-mass Pleiades members (including nearly 100 with M=<0.45 M_{sun}_), measured from photometric monitoring of the cluster conducted by the Palomar Transient Factory in late 2011 and early 2012. These periods extend the portrait of stellar rotation at 125 Myr to the lowest-mass stars and re-establish the Pleiades as a key benchmark for models of the transport and evolution of stellar angular momentum. Combining our new P_rot_ with precise BVIJHK photometry reported by Stauffer et al. (2007, J/ApJS/172/663) and Kamai et al. (2014, J/AJ/148/30), we investigate known anomalies in the photometric properties of K and M Pleiades members. We confirm the correlation detected by Kamai et al. between a star's P_rot_ and position relative to the main sequence in the cluster's color-magnitude diagram. We find that rapid rotators have redder (V-K) colors than slower rotators at the same V, indicating that rapid and slow rotators have different binary frequencies and/or photospheric properties. We find no difference in the photometric amplitudes of rapid and slow rotators, indicating that asymmetries in the longitudinal distribution of starspots do not scale grossly with rotation rate.
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- ID:
- ivo://CDS.VizieR/I/290
- Title:
- Pulkovo catalogue of 58483 stars (Pul-3)
- Short Name:
- I/290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of positions and proper motions of 58483 stars (Pul-3) has been constructed at the Pulkovo observatory. The Pul-3 is based on the results of measurements of the photographic plates ((x,y)-data) with galaxies (Deutsch's plan). The observations were made with Pulkovo Normal Astrograph (F=3467mm, D=330mm) during the periods from 1935 till 1960 (the first epoch) and from 1969 till 1986 (the second epoch). The radius of working field was 50 arcmin for all plates. The exposure times were 1 hour. All plates were taken near the meridian. The measurements of the plates were made at the Pulkovo observatory in 1970-s and in 1980-s with ASCORECORD measuring machine. Photographic magnitudes of these stars have been determined at the Pulkovo observatory. The Pulkovo plates contain stars mainly 12-16.5 magnitudes in 146 field in declination zone from -5 to +85 degrees. The maximal density of stars in the Pulkovo plates is 500 stars per square degree. The Tycho-2 catalogue (Cat. <I/259>) has been used as a reference catalogue for astrometric reductions of the photographic plates. The great stars density of the Tycho-2 provides 40-65 reference stars in working field of the Pulkovo plates. Only approximate equatorial coordinates of the optical centers of all plates had been known in initial stage of construction of the Pul-3 catalogue and thus recalculation of ones has been done. A six-parameter plate model has been used for the astrometric reduction of the plates. The residuals of the tangential coordinates of reference stars have been analysed to investigate residual systematic errors. The coma parameters have been determined and coma-dependent systematic errors have been excluded. The magnitude-dependent systematic errors and color-dependent ones were investigated. The most significant corrections for magnitude equation have been obtained for stars brighter than 9 magnitude and fainter than 14 magnitude. The most significant color corrections have been obtained in equatorial zone for declinations of stars. The corrected coordinates of all stars have been determined. On the whole, recalculation of the plates optical centers and taking into account of all revealed systematic errors provide improvement of the accuracy of coordinates of stars on 64mas and 51mas for right ascension and declination correspondingly. The new proper motions have been determined for all stars. The mean position has been calculated at the mean epoch of observations of each star using it proper motion. The mean epoch of the Pul-3 is 1963.25. The internal positional accuracy of the Pul-3 catalogue at the mean epoch of observations is 80mas. The internal accuracy of the proper motions is 5mas/yr. Comparisons of the Pul-3 with Tycho-2 and ARIHIP have been done. The Pul-3 external positional accuracy relative to Tycho-2 is 150mas at the mean epoch of the Pulovo plates. The Pul-3 catalogue successfully represents the Tycho-2 system for more than 50000 stars which are fainter than 12 magnitude in 146 fields. The stars from the Pul-3 catalogue may be used as reference stars for reductions of the positional CCD-observations of the extragalactic radio sources and small bodies of the Solar system. The 40-years difference between Pul-3 observational epoch and modern epoch will allow to determine high precision proper motions of the faint stars of the Pul-3 catalogue (about 2mas/yr-3mas/yr). Proper motions of stars from Pul-3 catalogue may be used for stellar kinematics investigations. There are two data files for user's convenience: - the file pul3.dat represents the Pul-3 catalogue; - the file centers.dat contains the equatorial coordinates of centers of the Pulkovo fields (RA, DE).
- ID:
- ivo://CDS.VizieR/I/321
- Title:
- Pulkovo SMP Photographic Catalogue
- Short Name:
- I/321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of new reduction of 1545 photographic observations of 14 selected asteroids' obtained with Normal Astrograph of Pulkovo observatory from 1948 to 1990 years presented. Photographic plates, stored in observatory's archive, was digitized using consumer flatbed scanner with special designed technique. The accuracy of measured photoplates was performed. The UCAC3 was used as reference catalog. The analysis of instrumental systematic effects, revealing in common distortion and magnitude equation, was performed and taken into account. The equatorial coordinates of 1378 single observations of selected asteroids was obtained and was made their comparison with results of reduction of this material obtained earlier. 1475 positions of stars with large proper motions from LSPM catalog was measured among background objects.
- ID:
- ivo://CDS.VizieR/J/ApJS/232/23
- Title:
- 27 pulsating DA WDs follow-up observations
- Short Name:
- J/ApJS/232/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs; a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) and duty cycle (>90%). The space-based photometry reveals pulsation properties previously inaccessible to ground- based observations. We observe a sharp dichotomy in oscillation mode line widths at roughly 800s, such that white dwarf pulsations with periods exceeding 800s have substantially broader mode line widths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: we identify the spherical degree of 87 out of 201 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra, we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low- and intermediate-mass stars. We find that 0.51-0.73M{sun} white dwarfs, which evolved from 1.7-3.0M{sun} ZAMS progenitors, have a mean rotation period of 35hr with a standard deviation of 28hr, with notable exceptions for higher-mass white dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/345
- Title:
- Pulsating pre-main-sequence stars in NGC6383
- Short Name:
- J/MNRAS/357/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search for pulsating pre-main-sequence (PMS) stars was performed in the young open cluster NGC 6383 using CCD time-series photometry in Johnson B and V filters. With an age of only ~1.7Myr all cluster members later than spectral type A0 have not reached the ZAMS yet, hence being ideal candidates for investigating PMS pulsation among A- and F-type stars. In total 286 stars have been analysed using classical Fourier techniques. From about a dozen stars within the boundaries of the classical instability strip, two stars were found to pulsate: NGC 6383 #170, with five frequencies simultaneously, and NGC 6383 #198, with a single frequency. In addition, NGC 6383 #152 is a suspected PMS variable star, but our data remain inconclusive. Linear, non-adiabatic models assuming PMS evolutionary phase and purely radial pulsation were calculated for the two new PMS pulsators. NGC 6383 #170 appears to pulsate radially in third and fifth overtones, while the other three frequencies seem to be of non-radial nature. NGC 6383 #198 pulsates mono-periodically, most probably in the third radial overtone. Magnitudes and BV colours were available in the literature for only one third of all stars and we used them for calibrating the remaining.
- ID:
- ivo://CDS.VizieR/J/AJ/162/149
- Title:
- Pulsational changes in classical cepheid X Cygni
- Short Name:
- J/AJ/162/149
- Date:
- 21 Mar 2022 00:19:54
- Publisher:
- CDS
- Description:
- Using an extensive archive for visual observations from the AAVSO, along with published times of maximum light, we determined a new model for the period of X Cygni. The best model is two linear fits for data before and after 1917 (JD2421512). Before that time the period is 16.38438{+/-}0.00036days. After we find a period of 16.386470{+/-}0.000028days. An examination of the O-C values for data after 1917 shows no clear evidence of a constant period change or of sinusoidal variations. The period looks to be constant. From an examination of H-alpha index measurements we find a drop in the value between data before 2013 October and data after 2014 July. This drop is not related to temperature and is likely related to mass loss in the star. Finally, we find that radial-velocity measurements match well with previously published values and show no seasonal variation over the 11yr of data. This again seems to limit the possibility of a companion.
- ID:
- ivo://CDS.VizieR/J/A+AS/77/447
- Title:
- Puppis window UBV photometry
- Short Name:
- J/A+AS/77/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photographic UBV photometry of 1302 stars in a 76 square-arcminute field in the Puppis window to U~16.9, (B, V)~21 is presented. The presence of an OB association at r~6kpc in this direction as reported by Stetson and FitzGerald (1985) is confirmed. No evidence of any more distant early-type stars is indicated.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/2689
- Title:
- PV Cep V(RI)c and IRAC photometry
- Short Name:
- J/MNRAS/413/2689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young Sun-like stars at the beginning of the pre-main-sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the star with the disc. Time-scales and wavelength dependence of the variability carry information on the physical mechanisms behind these interactions. We conducted multi-epoch, multiwavelength study of PV Cep, a strongly variable, accreting PMS star. By combining our own observations from 2004 to 2010 with archival and literature data, we show that PV Cep started a spectacular fading in 2005, reaching an IC-band amplitude of 4mag. Analysis of variation of the optical and infrared fluxes, colour indices and emission line fluxes suggests that the photometric decline in 2005-2009 resulted from an interplay between variable accretion and circumstellar extinction: since the central luminosity of the system is dominated by accretion, a modest drop in the accretion rate could induce the drastic restructuring of the inner disc. Dust condensation in the inner disc region might have resulted in the enhancement of the circumstellar extinction.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A144
- Title:
- QSO candidates catalog with APOP & ALLWISE (QCC)
- Short Name:
- J/A+A/618/A144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasars are spatially stationary, and they are essential objects in astrometry when defining reference frames. However, the census of quasars is far from complete. Mid-infared colors can be used to find quasar candidates because AGNs show a peculiar appearance in mid-infrared color, but these methods are incapable of separating quasars from AGNs.The aim of our study is to use astrometric and mid-infrared methods to select quasars and get a reliable quasar candidates catalog. We used a near-zero proper motion criterion in conjuction with WISE (all-sky Wide-field Infrared Survey Explorer) [W1-W2] color to select quasar candidates. The [W1-W2] color criterion is defined by the linear boundary of two samples: LAMOST DR5 quasars, which serve as the quasar sample, and LAMOST DR5 stars/galaxies, which serve as the non-quasar sample. The contamination and completeness are evaluated. We present a catalog of 662753 quasar candidates, with a completeness of about 75% and a reliability of 77.2%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/223
- Title:
- QSO candidates selection in VO era
- Short Name:
- J/MNRAS/396/223
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a method for the photometric selection of candidate quasars in multiband surveys. The method makes use of a priori knowledge derived from a subsample of spectroscopic confirmed quasi-stellar objects (QSOs) to map the parameter space. The disentanglement of QSOs candidates and stars is performed in the colour space through the combined use of two algorithms, the probabilistic principal surfaces and the negative entropy clustering, which are for the first time used in an astronomical context. Both methods have been implemented in the voneural package on the Astrogrid Virtual Observatory platform. Even though they belong to the class of the unsupervised clustering tools, the performances of the method are optimized by using the available sample of confirmed quasars and it is therefore possible to learn from any improvement in the available 'base of knowledge'. The method has been applied and tested on both optical and optical plus near-infrared data extracted from the visible Sloan Digital Sky Survey (SDSS) and infrared United Kingdom Infrared Deep Sky Survey-Large Area Survey public data bases. In all cases, the experiments lead to high values of both efficiency and completeness, comparable if not better than the methods already known in the literature. A catalogue of optical candidate QSOs extracted from the SDSS Data Release 7 Legacy photometric data set has been produced.
