ترغب بنشر مسار تعليمي؟ اضغط هنا

The catalog of short periods stars from the Pi of the Sky data

109   0   0.0 ( 0 )
 نشر من قبل Agnieszka Majczyna
 تاريخ النشر 2008
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

Based on the data from the Pi of the Sky project we made a catalog of the variable stars with periods from 0.1 to 10 days. We used data collected during a period of two years (2004 and 2005) and classified 725 variable stars. Most of the stars in our catalog are eclipsing binaries - 464 (about 64%), while the number of pulsating stars is 125 (about 17%). Our classification is based on the shape of the light curve, as in the GCVS catalog. However, some stars in our catalog were classified as of different type than in the GCVS catalog. We have found periods for 15 stars present in the GCVS catalog with previously unknown period.


قيم البحث

اقرأ أيضاً

Most of the sky has been imaged with NOAOs telescopes from both hemispheres. While the large majority of these data were obtained for PI-led projects and almost all of the images are publicly available, only a small fraction have been released to the community via well-calibrated and easily accessible catalogs. We are remedying this by creating a catalog of sources from most of the public data taken on the CTIO-4m+DECam and the KPNO-4m+Mosaic3. This catalog, called the NOAO Source Catalog (NSC), contains over 2.9 billion unique objects, 34 billion individual source measurements, covers ~30,000 square degrees of the sky, has depths of ~23rd magnitude in most broadband filters with ~1-2% photometric precision, and astrometric accuracy of ~7 mas. In addition, ~2 billion objects and ~21,000 square degrees of sky have photometry in three or more bands. The NSC will be useful for exploring stellar streams, dwarf satellite galaxies, QSOs, high-proper motion stars, variable stars and other transients. The NSC catalog is publicly available via the NOAO Data Lab service.
We announce the second data release (DR2) of the NOIRLab Source Catalog (NSC), using 412,116 public images from CTIO-4m+DECam, the KPNO-4m+Mosaic3 and the Bok-2.3m+90Prime. NSC DR2 contains over 3.9 billion unique objects, 68 billion individual sourc e measurements, covers $approx$35,000 square degrees of the sky, has depths of $approx$23rd magnitude in most broadband filters with $approx$1-2% photometric precision, and astrometric accuracy of $approx$7 mas. Approximately 1.9 billion objects within $approx$30,000 square degrees of sky have photometry in three or more bands. There are several improvements over NSC DR1. DR2 includes 156,662 (61%) more exposures extending over 2 more years than in DR1. The southern photometric zeropoints in $griz$ are more accurate by using the Skymapper DR1 and ATLAS-Ref2 catalogs, and improved extinction corrections were used for high-extinction regions. In addition, the astrometric accuracy is improved by taking advantage of Gaia DR2 proper motions when calibrating the WCS of individual images. This improves the NSC proper motions to $sim$2.5 mas/yr (precision) and $sim$0.2 mas/yr (accuracy). The combination of sources into unique objects is performed using a DBSCAN algorithm and mean parameters per object (such as mean magnitudes, proper motion, etc.) are calculated more robustly with outlier rejection. Finally, eight multi-band photometric variability indices are calculated for each object and variable objects are flagged (23 million objects). NSC DR2 will be useful for exploring solar system objects, stellar streams, dwarf satellite galaxies, QSOs, variable stars, high-proper motion stars, and transients. Several examples of these science use cases are presented. The NSC DR2 catalog is publicly available via the NOIRLabs Astro Data Lab science platform.
We present measurements of the spectral properties for a total of 526,265 quasars, out of which 63% have continuum S/N$>3$ pixel$^{-1}$, selected from the fourteenth data release of the Sloan Digital Sky Survey (SDSS-DR14) quasar catalog. We performe d a careful and homogeneous analysis of the SDSS spectra of these sources, to estimate the continuum and line properties of several emission lines such as H${alpha}$, H${beta}$, H${gamma}$, Mg textsc{ii}, C textsc{iii]}, C textsc{iv} and Ly${alpha}$. From the derived emission line parameters, we estimated single-epoch virial black hole masses ($M_{mathrm{BH}}$) for the sample using H${beta}$, Mg textsc{ii} and C textsc{iv} emission lines. The sample covers a wide range in bolometric luminosity ($log L_{mathrm{bol}}$; erg s$^{-1}$) between 44.4 and 47.3 and $log M_{mathrm{BH}}$ between 7.1 and 9.9 $M_{odot}$. Using the ratio of $L_{mathrm{bol}}$ to the Eddington luminosity as a measure of the accretion rate, the logarithm of the accretion rate is found to be in the range between $-$2.06 and 0.43. We performed several correlation analyses between different emission line parameters and found them to match with that known earlier using smaller samples. We noticed that strong Fe textsc{ii} sources with large Balmer line width, and highly accreting sources with large $M_{mathrm{BH}}$ are rare in our sample. We make available online an extended and complete catalog that contains various spectral properties of 526,265 quasars derived in this work along with other properties culled from the SDSS-DR14 quasar catalog.
We present the full spectroscopic white dwarf and hot subdwarf sample from the SDSS first data release, DR1. We find 2551 white dwarf stars of various types, 240 hot subdwarf stars, and an additional 144 objects we have identified as uncertain white dwarf stars. Of the white dwarf stars, 1888 are non-magnetic DA types and 171, non-magnetic DBs. The remaining (492) objects consist of all different types of white dwarf stars: DO, DQ, DC, DH, DZ, hybrid stars like DAB, etc., and those with non-degenerate companions. We fit the DA and DB spectra with a grid of models to determine the Teff and log(g) for each object. For all objects, we provide coordinates, proper motions, SDSS photometric magnitudes, and enough information to retrieve the spectrum/image from the SDSS public database. This catalog nearly doubles the known sample of spectroscopically-identified white dwarf stars. In the DR1 imaged area of the sky, we increase the known sample of white dwarf stars by a factor of 8.5. We also comment on several particularly interesting objects in this sample.
We measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5-M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the South, producing two-minu te cadence light curves since 2016. Long-term, high-cadence observations of rotating flare stars probe the complex relationship between stellar rotation, starspots, and superflares. We detect periods from 0.3487 to 104 d, and observe amplitudes from 0.008 to 0.216 g mag. We find the Evryscope amplitudes are larger than those in TESS with the effect correlated to stellar mass (p-value=0.01). We compute the Rossby number (Ro), and find our sample selected for flaring has twice as many intermediate rotators (0.04<Ro<0.4) as fast (Ro<0.04) or slow (Ro>0.44) rotators; this may be astrophysical or a result of period-detection sensitivity. We discover 30 fast, 59 intermediate, and 33 slow rotators. We measure a median starspot coverage of 13% of the stellar hemisphere and constrain the minimum magnetic field strength consistent with our flare energies and spot coverage to be 500 G, with later-type stars exhibiting lower values than earlier-types. We observe a possible change in superflare rates at intermediate periods. However, we do not conclusively confirm the increased activity of intermediate rotators seen in previous studies. We split all rotators at Ro~0.2 into Prot<10 d and Prot>10 d bins to confirm short-period rotators exhibit higher superflare rates, larger flare energies, and higher starspot coverage than do long-period rotators, at p-values of 3.2 X 10^-5, 1.0 X 10^-5, and 0.01, respectively.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا