- ID:
- ivo://CDS.VizieR/J/A+A/424/1101
- Title:
- Variable Stars in the field of {omega} Cen
- Short Name:
- J/A+A/424/1101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a photometric survey for variable stars in the field of the globular cluster Omega Centauri. The observed region was centered roughly on the cluster core and covered 644arcmin^2^. The cluster was monitored on 59 nights in 1999 and 2000. A total of 117 new variables were identified. Among them there are 16 RR Lyr-type stars, 35 SX Phe variables and 26 eclipsing binaries. A comprehensive catalog including all variable stars so far reported from the cluster field is presented. We list basic photometric properties and provide finding charts for a total of 392 objects. For 313 of them new BV light curves were obtained. The presented sample includes several interesting variables, such as SX Phe stars with extremely short periods of pulsation and several candidates for pulsating K giants. Optical counterparts to 9 X-ray sources detected by XMM and Chandra telescopes were identified: all of them are likely to be foreground variables not related to the cluster.
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Search Results
- ID:
- ivo://CDS.VizieR/II/247
- Title:
- Variable Stars in the Large Magellanic Clouds
- Short Name:
- II/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The MACHO Project is a collaboration between scientists at the Mt. Stromlo & Siding Spring Observatories, the Center for Particle Astrophysics at the Santa Barbara, San Diego, & Berkeley campuses of the University of California, and the Lawrence Livermore National Laboratory. The primary aim of the project is a search for dark matter in the halo of the Milky Way in the form of objects like brown dwarfs or planets also named MACHOs, for MAssive Compact Halo Objects. The signature of these MACHOs is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it is necessary to monitor photometrically several million stars for a period of years in order to obtain a useful detection rate. The MACHO project is described by Alcock et al. (1992, in "Robotic Telescopes in the 1990s", A.V. Fillippenko Ed., ASP Conf. Series 34, p.193). A dedicated 1.27-m telescope at Mount Stromlo, Australia is used to obtain observations of the LMC year-round, using a camera imaging a field of view of 0.5 square degrees at prime focus. Photometric observations of the LMC fields are obtained in two bandpasses simultaneously, using a dichroic beamsplitter to direct the blue (440-590nm) and red (590-780nm) light onto 2x2 mosaics of 2048x2048 Loral CCDs; the 15um pixels map to 0.63arcsec on the sky. The photometric reduction methods are detailed in Alcock et al. (1996ApJ...461...84A).
- ID:
- ivo://CDS.VizieR/J/AJ/108/932
- Title:
- Variable stars in the SMC cluster NGC 330
- Short Name:
- J/AJ/108/932
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V and I band CCD images of the SMC cluster NGC 330 have been obtained over an interval of 4 years with the aim of identifying variable stars in and around this rich, young cluster. The search has revealed 22 Cepheid variables, of which 14 are newly discovered. All of these appear to belong to the SMC field population rather than being cluster members. Twenty long-period variables, and nine other variables were identified including two eclipsing variables (one newly discovered), and four close binary stars, two of which show emission lines. The Cepheids indicate that only small to moderate amounts of convective core overshoot (f_ov_<~0.25) occur during the main-sequence phases for stars of mass 2-3M_{sun}_. The Cepheid period-luminosity-color relation obtained from VI photometry, when compared to the theoretical relation of Chiosi, et al. (1993ApJS...86..541C), yields a distance modulus for the short-period Cepheids observed during this study of 18.92 if no overshoot is assumed, or 18.72 if moderate overshoot (f_ov=0.25) is adopted. Only two modes of pulsation are present in this group of Cepheids, most likely they are the fundamental and first overtone.
- ID:
- ivo://CDS.VizieR/J/A+AS/128/19
- Title:
- Variable stars in 47 Tuc fields 104A-E
- Short Name:
- J/A+AS/128/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry for 42 variables from the field of 47 Tuc = NGC 104 is presented. VI photometry for a large set of stars from the surveyed fields is also given.
- ID:
- ivo://CDS.VizieR/J/AJ/136/1921
- Title:
- Variable stars of Draco dSph
- Short Name:
- J/AJ/136/1921
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a CCD survey of variable stars in the Draco dwarf spheroidal galaxy. This survey, which has the largest areal coverage since the original variable star survey by Baade & Swope (1961AJ.....66..300B), includes photometry for 270 RR Lyrae (RRL) stars, 9 anomalous Cepheids (ACs), 2 eclipsing binaries, and 12 slow, irregular red variables, as well as 30 background QSOs. Twenty-six probable double-mode RRL stars were identified. Observed parameters, including mean V and I magnitudes, V amplitudes, and periods, have been derived.
- ID:
- ivo://CDS.VizieR/J/AJ/159/121
- Title:
- V-band light curve & RVs of the Cepheid V473Lyr
- Short Name:
- J/AJ/159/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V473Lyr is a classical Cepheid that is unique in having substantial amplitude variations with a period of approximately 3.3yr, thought to be similar to the Blazhko variations in RR Lyrae stars. We obtained an X-ray Multi-Mirror Mission (XMM)-Newton observation of this star to follow up a previous detection in X-rays. Rather than the X-ray burst and rapid decline near maximum radius seen in {delta}Cephei itself, the X-ray flux in V473Lyr remained constant for a third of the pulsation cycle covered by the observation. Thus the X-rays are probably not produced by the changes around the pulsation cycle. The X-ray spectrum is soft (kT=0.6keV), with X-ray properties consistent with a young low-mass companion. Previously there was no evidence of a companion in radial velocities or in Gaia and Hipparcos proper motions. While this rules out companions that are very close or very distant, a binary companion at a separation between 30 and 300au is possible. This is an example of an X-ray observation revealing evidence of a low-mass companion, which is important in completing the mass ratio statistics of binary Cepheids. Furthermore, the detection of a young X-ray bright companion is a further indication that the Cepheid (primary) is a Population I star, even though its pulsation behavior differs from other classical Cepheids.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A48
- Title:
- V-band photometry of asteroids from ASAS-SN
- Short Name:
- J/A+A/654/A48
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present V-band photometry of the 20000 brightest asteroids using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) between 2012 and 2018. We were able to apply the convex inversion method to more than 5000 asteroids with more than 60 good measurements in order to derive their sidereal rotation periods, spin axis orientations, and shape models. We derive unique spin state and shape solutions for 760 asteroids, including 163 new determinations. This corresponds to a success rate of about 15%, which is significantly higher than the success rate previously achieved using photometry from surveys. We derive the first sidereal rotation periods for additional 69 asteroids. We find good agreement in spin periods and pole orientations for objects with prior solutions. We obtain a statistical sample of asteroid physical properties that is sufficient for the detection of several previously known trends, such as the underrepresentation of slow rotators in current databases, and the anisotropic distribution of spin orientations driven by the nongravitational forces. We also investigate the dependence of spin orientations on the rotation period. Since 2018, ASAS-SNhas been observing the sky with higher cadence and a deeper limiting magnitude, which will lead to many more new solutions in just a few years.
- ID:
- ivo://CDS.VizieR/J/A+A/445/617
- Title:
- V823 Cas BV(RI)c differential photometry
- Short Name:
- J/A+A/445/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0+f2=2f1 resonance may act in triple mode pulsators.
- ID:
- ivo://CDS.VizieR/J/A+A/542/A43
- Title:
- V2493 Cyg BVRI long term photometry
- Short Name:
- J/A+A/542/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new results from optical photometric and spectroscopic observations of the eruptive pre-main sequence star V2493 Cyg (HBC 722). The object has continued to undergo significant brightness variations over the past few months and is an ideal target for follow-up observations.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A15
- Title:
- V795 Her differential photometry
- Short Name:
- J/A+A/540/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V-band CCD observations of the cataclysmic variable V795 Her obtained between 2008 and 2010. The observing run on a given night consisted of a dense series of V-band images (exposure time of 20 seconds). Heliocentric Julian Date of each CCD image is given for the center of the exposure. A typical standard deviation of a single measurement of the magnitude of V795 Her on a given CCD frame was about 0.01 mag. GSC 02595-00575 (GSC2.3 N3JJ000148) was used as the comparison star (abbreviated as C) while GSC 02595-00718 served as the check star (abbreviated as C1).
