- 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.
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- ID:
- ivo://CDS.VizieR/J/ApJ/848/68
- Title:
- Abundances & RVs of stable and Blazhko RRc stars
- Short Name:
- J/ApJ/848/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed series of spectra obtained for 12 stable RRc stars observed with the echelle spectrograph of the du Pont telescope at Las Campanas Observatory and we analyzed the spectra of RRc Blazhko stars discussed by Govea+ (2014, J/ApJ/782/59). We derived model atmosphere parameters, [Fe/H] metallicities, and [X/Fe] abundance ratios for 12 species of 9 elements. We co-added all spectra obtained during the pulsation cycles to increase signal to noise and demonstrate that these spectra give results superior to those obtained by co-addition in small phase intervals. The RRc abundances are in good agreement with those derived for the RRab stars of Chadid+ (2017ApJ...835..187C). We used radial velocity (RV) measurements of metal lines and H{alpha} to construct variations of velocity with phase, and center-of-mass velocities. We used these to construct RV templates for use in low- to medium-resolution RV surveys of RRc stars. Additionally, we calculated primary accelerations, radius variations, and metal and H{alpha} velocity amplitudes, which we display as regressions against primary acceleration. We employ these results to compare the atmosphere structures of metal-poor RRc stars with their RRab counterparts. Finally, we use the RV data for our Blazhko stars and the Blazhko periods of Szczygiel & Fabrycky (2007, J/MNRAS/377/1263) to falsify the Blazhko oblique rotator hypothesis.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/I/280B
- Title:
- All-Sky Compiled Catalogue of 2.5 million stars
- Short Name:
- I/280B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The All-Sky Compiled Catalogue of 2501313 stars (ASCC-2.5) with the limiting magnitude V=12-14 is a result of a merging of star lists from present day large high-precision catalogues from space (Hipparcos- Tycho family catalogues: Hipparcos main catalogue including Multiple System Annex [I/239], Tycho-1 [I/239], Tycho-2 [I/259], ACT-RC [I/246], TRC [I/250]) and ground-based (PPM-N [I/146], PPM-S [I/193], PPM-add [I/208], CMC11 [I/256]) observations and reduction to standard systems of corresponding stellar data. The data from the Tycho-2 Spectral Type Catalog [III/231], and the 2MASS All-Sky Catalog of Point Sources [II/246] are added. The basic stellar data presented in the ASCC-2.5 are the equatorial coordinates (J2000, epoch 1991.25), proper motions in the Hipparcos system, B and/or V stellar magnitudes in the Johnson system. Additionally, for some stars we give trigonometric parallaxes, spectral classes in the MK or HD system, multiplicity and variability flags, Hipparcos, Tycho-2, HD, DM designations. Equatorial coordinates and their standard errors were taken from the source catalogues in accordance with the priority: Hipparcos [I/239/hip_main], Tycho-2 [I/259], Tycho-1 [I/239/tyc_main], CMC11 [I/256], PPM [I/146,I/193,I/208]. Proper motions from the source catalogues were compared with Hipparcos data.The compiled proper motions in the Hipparcos system and their standard errors were computed as the weighted means. The weights were set in accordance with the proper motion errors listed for individual stars in the source catalogues. Trigonometric parallaxes are taken from the Hipparcos and Tycho-1 catalogues. Stellar B, V magnitudes were determined on the basis of the ground- based photometric data taken from CMC11, Hipparcos, as well as space BT, VT from Tycho-1, Tycho-2. Magnitudes from the PPM catalogue were used if no other photometric data were available. Tycho data were transformed to the Johnson system via: V = VT - 0.09 (B-V)T + dV, (B-V) = 0.850 (B-V)T + d(B-V), i.e. using the recommendations from the Introduction to the Tycho catalogue and including additional corrections dV and d(B-V). These additional corrections were determined by comparison with ground-based data in the Johnson system. These corrections depend non-linearly on colour and reach 0.02 and 0.04 mag, respectively. Infrared stellar magnitudes J, H, K_s_ and their errors were copied from the 2MASS catalogue. Spectral classes in the MK or HD systems were taken from Hipparcos, CMC11, PPM, and Tycho-2 Spectral Type catalogues. Multiplicity and variability flags were taken from Tycho-1, Tycho-2, Hipparcos, CMC11, and PPM catalogues. The 1st version of the ASCC-2.5 contained some errors in the zones -1 to +1 degree which have been corrected (see details in the "History" section below). The 2nd version included a new file (ccadd.dat) containing the previously missing stars (including components of multiple systems). Note that the ASCC numbers did not change between the two versions, but additional numbers (2600001 to 2603318) were assigned. In the present 3rd version of the ASCC-2.5 the stars from file ccadd.dat are inserted in the basic files in accordance with their coordinates. Stars in the ASCC-2.5 are divided into 30 files ordered by declination (North and South polar caps and 28 bands of 5 degrees width), then sorted in order of right ascension within each file.
- ID:
- ivo://CDS.VizieR/J/A+A/504/959
- Title:
- Amplitudes of single-mode Cepheids
- Short Name:
- J/A+A/504/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dependence of amplitude on the pulsation period differs from other Cepheid-related relationships. We attempt to revise the period-amplitude (P-A) relationship of Galactic Cepheids based on multi-colour photometric and radial velocity data. Reliable P-A graphs for Galactic Cepheids constructed for the U, B, V, Rc, and Ic photometric bands and pulsational radial velocity variations facilitate investigations of previously poorly studied interrelations between observable amplitudes. The effects of both binarity and metallicity on the observed amplitude, and the dichotomy between short- and long-period Cepheids can both be studied. A homogeneous data set was created that contains basic physical and phenomenological properties of 369 Galactic Cepheids. Pulsation periods were revised and amplitudes were determined by the Fourier method. P-A graphs were constructed and an upper envelope to the data points was determined in each graph. Correlations between various amplitudes and amplitude-related parameters were searched for, using Cepheids without known companions.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1475
- Title:
- ARAUCARIA: NGC 7793 Cepheids
- Short Name:
- J/AJ/140/1475
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For the first time, we have detected Cepheid variables in the Sculptor Group spiral galaxy NGC 7793. From wide-field images obtained in the optical V and I bands on 56 nights in 2003-2005, we have discovered 17 long-period (24-62 days) Cepheids whose periods and mean magnitudes define tight period-luminosity relations. We use the (V-I) Wesenheit index to determine a reddening-free true distance modulus to NGC 7793 of 27.68+/-0.05mag (internal error) +/-0.08mag (systematic error).
- ID:
- ivo://CDS.VizieR/J/AJ/132/2556
- Title:
- ARAUCARIA project: Cepheids in NGC 55
- Short Name:
- J/AJ/132/2556
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have detected, for the first time, Cepheid variables in the Sculptor Group SB(s)m galaxy NGC 55. From wide-field images obtained in the optical V and I bands during 77 nights in 2002-2003, we have found 143 Cepheids with periods ranging from 5.6 to 175.9 days; 133 of these objects have periods longer than 10 days, making NGC 55 to date the galaxy with the largest known number of long-period Cepheids in the Sculptor Group.
- ID:
- ivo://CDS.VizieR/J/AJ/134/594
- Title:
- Araucaria project: Cepheids in WLM galaxy
- Short Name:
- J/AJ/134/594
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted an extensive wide-field imaging survey for Cepheid variables in the Local Group irregular galaxy WLM. From data obtained on 101 nights, we have discovered 60 Cepheids, which include 14 of the 15 Cepheid variables previously detected by Sandage and Carlson. Our Cepheid survey in WLM should be practically complete down to a period of 3-days. Importantly, we have found for the first time a long-period Cepheid (P=54.2-days) in this galaxy, alleviating the problem that WLM with its many blue, massive stars does not contain Cepheids with periods longer than about 10-days.
- ID:
- ivo://CDS.VizieR/J/AJ/123/789
- Title:
- ARAUCARIA project: NGC 300 Cepheid variables
- Short Name:
- J/AJ/123/789
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a survey for Cepheid variables in the Sculptor group spiral NGC 300. Based on observations obtained with the Wide-Field Camera at the 2.2m ESO/MPI telescope at the La Silla observatory in Chile during 29 nights spread over a 5.3 month interval. The telescope was equipped with the ESO mosaic Wide-Field Camera (WFI) consisting of eight 2048x4098 pixel arrays. The CCDs were separated by gaps of 23.8" and 14.3" in right ascension and declination, respectively. The total field of view was about 34'x33' with a scale of 0.238"/pixel. 117 Cepheids and 12 Cepheid candidates were found, which cover the period range from 115 to 5.4 days. We present a catalog that provides equatorial coordinates, period, time of maximum brightness, and intensity mean B and V magnitudes for each variable, and we show phased B and V light curves for all the Cepheids found. We also present the individual B and V observations for each Cepheid in our catalog. During our search we rediscovered all 18 previously known Cepheids and confirmed the Cepheid nature of three Cepheid candidates from the previous photographic survey of Graham (1984AJ.....89.1332G). Star V4 in Graham's list (1984AJ.....89.1332G), classified by him as an eclipsing binary, turns out to be another Cepheid. We find very good agreement between our photometry and that obtained by Freedman et al. (1992ApJ...396...80F) from ground-based CCD data for common stars. Using the earlier data together with our new data, we were able to significantly improve the periods for 15 Cepheids in our sample.
