- ID:
- ivo://CDS.VizieR/J/A+A/503/651
- Title:
- Variable stars in a VLT/VIMOS field in Carina
- Short Name:
- J/A+A/503/651
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for variable stars in deep V-band images of a field towards the Galactic plane in Carina. The images were taken with VIMOS instrument at ESO VLT during 4 contiguous nights in April 2005. We detected 348 variables among 50897 stars in the magnitude range between V=15.4 and V=24.5mag. Upon detection, we classified the variables by direct eye inspection of their light curves. All variable objects but 9 OGLE transits in the field are new discoveries. We provide a complete catalog of all variables which includes eclipsing/ellipsoidal binaries, miscellaneous pulsators (mostly delta Scuti-type variables), stars with flares and other (irregular and likely long-period) variables. Only two of the stars in our sample are known to host planets. Our result give some implications for future large variability surveys.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/129/2856
- Title:
- Variable stars in NGC 6791
- Short Name:
- J/AJ/129/2856
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 6791, a very old, populous, metal-rich cluster. We have monitored the cluster for over 300hr, spread over 84 nights. We have not detected any good transiting planet candidates. Given the photometric precision and temporal coverage of our observations and the current best estimates for the frequency and radii of short-period planets, the expected number of detectable transiting planets in our sample is 1.5. We have discovered 14 new variable stars in the cluster, most of which are eclipsing binaries, and present high-precision light curves spanning 2 years for these new variables and also the previously known variables.
- ID:
- ivo://CDS.VizieR/J/PASP/131/H4201
- Title:
- Variable stars in Southern polar region
- Short Name:
- J/PASP/131/H4201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (~=5% or greater) variable objects among 160000 bright stars (m_v_<14.5) near the South Celestial Pole. We developed a machine-learning-based spectral classifier to identify eclipse and transit candidates with M-dwarf or K-dwarf host stars, and potential low-mass secondary stars or gas-giant planets. The large amplitude transit signals from low-mass companions of smaller dwarf host stars lessens the photometric precision and systematics removal requirements necessary for detection, and increases the discoveries from long-term observations with modest light-curve precision among the faintest stars in the survey. The Evryscope is a robotic telescope array that observes the Southern sky continuously at 2-minute cadence, searching for stellar variability, transients, transits around exotic stars and other observationally challenging astrophysical variables. The multi-year photometric stability is better than 1% for bright stars in uncrowded regions, with a 3{sigma} limiting magnitude of g=16 in dark time. In this study, covering all stars 9<m_v_<14.5, in declinations -75{deg} to -90{deg}, and searching for high-amplitude variability, we recover 346 known variables and discover 303 new variables, including 168 eclipsing binaries. We characterize the discoveries and provide the amplitudes, periods, and variability type. A 1.7R_J_ planet candidate with a late K-dwarf primary was found and the transit signal was verified with the PROMPT telescope network. Further follow-up revealed this object to be a likely grazing eclipsing binary system with nearly identical primary and secondary K5 stars. Radial-velocity measurements from the Goodman Spectrograph on the 4.1 meter SOAR telescope of the likely lowest-mass targets reveal that six of the eclipsing binary discoveries are low-mass (0.06-0.37M_{sun}_) secondaries with K-dwarf primaries, strong candidates for precision mass-radius measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/523/248
- Title:
- Variable stars in the Galactic center
- Short Name:
- J/ApJ/523/248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report results of a time series analysis of high-resolution K-band imaging, photometry, and polarimetry of stars in the Galactic center cluster covering 7 consecutive years. In our statistical sample with m_K_<13, about half of the stars show indication of variability consistent with most of them being long-period variable, asymptotic giant branch stars. Some long-period variables already proposed in the literature are confirmed. They are identified with asymptotic giant branch stars. For the first time we show that the bright He I source IRS 16SW is a short-period variable with a period of ~9.72 days. It is most likely an eclipsing binary with a lower mass limit of >=100M_{sun}_. This confirms previous modeling of characteristics of the near-infrared spectra, which also indicated that IRS 16SW is a massive, young hot star. We also present the results of a polarization survey covering the central parsec of the Galaxy. Stars whose polarization vectors differ from the overall polarization, which is parallel to the Galactic plane, are mostly situated in the "minispiral", a region of high thermal flux density at centimeter radio wavelengths. Some of these sources appear extended in the high-resolution images and have featureless red spectra. We interpret these objects as young stars that may have just recently been formed and are still embedded in a dust shell.
- ID:
- ivo://CDS.VizieR/J/other/JAD/15.2
- Title:
- VBLUW photometry of eclipsing binary stars
- Short Name:
- J/other/JAD/15.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VBLUW photometric observations of 13 eclipsing binary stars carried out by C.J. van Houten with the Walraven 5-color photometer between 1965 and 1978 are presented together with a first analysis of the orbital periods.
- ID:
- ivo://CDS.VizieR/J/AJ/151/66
- Title:
- Velocities of WOCS 24009 and WOCS 40007 in NGC 6819
- Short Name:
- J/AJ/151/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our study of the old (~2.5Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVR_C_I_C_) and spectroscopic observations of the detached eclipsing binary WOCS 24009 (Auner 665; KIC5023948) with a short orbital period of 3.6 days. WOCS 24009 is a triple-lined system, and we verify that the brightest star is physically orbiting the eclipsing binary using radial velocities and eclipse timing variations. The eclipsing binary components have masses M_B_=1.090+/-0.010M_{sun}_ and M_C_=1.075+/-0.013M_{sun}_, and radii R_B_=1.099+/-0.006+/-0.005R_{sun}_and R_C_=1.069+/-0.006+/-0.013R_{sun}_. The bright non-eclipsing star resides at the cluster turnoff, and ultimately its mass will directly constrain the turnoff mass: our preliminary determination is M_A_=1.251+/-0.057M_{sun}_. A careful examination of the light curves indicates that the fainter star in the eclipsing binary undergoes a very brief period of total eclipse, which enables us to precisely decompose the light of the three stars and place them in the color-magnitude diagram (CMD). We also present improved analysis of two previously discussed detached eclipsing stars in NGC6819 (WOCS40007 and WOCS23009) en route to a combined determination of the cluster's distance modulus (m-M)_V_=12.38+/-0.04. Because this paper significantly increases the number of measured stars in the cluster, we can better constrain the age of the CMD to be 2.21+/-0.10+/-0.20Gyr. Additionally, using all measured eclipsing binary star masses and radii, we constrain the age to 2.38+/-0.05+/-0.22Gyr. The quoted uncertainties are estimates of measurement and systematic uncertainties (due to model physics differences and metal content), respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A117
- Title:
- Velocity curves of SW CMa and HW CMa
- Short Name:
- J/A+A/537/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate physical properties of eclipsing stars provide important constraints on models of stellar structure and evolution, especially when combined with spectroscopic information on their chemical composition. Empirical calibrations of the data also lead to accurate mass and radius estimates for exoplanet host stars. Finally, accurate data for unusual stellar subtypes, such as Am stars, also help to unravel the cause(s) of their peculiarities. We aim to determine the masses, radii, effective temperatures, detailed chemical composition and rotational speeds for the Am-type eclipsing binaries SWCMa (A4-5m) and HWCMa (A6m) and compare them with similar normal stars.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A150
- Title:
- 10 very-low-mass stars photometry
- Short Name:
- J/A+A/625/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements of the physical properties of stars at the lower end of the main sequence are scarce. In this context we report masses, radii and surface gravities of ten very-low-mass stars in eclipsing binary systems, with orbital periods of the order of several days. The objects probe the stellar mass-radius relation in the fully convective regime, M*<0.35M_{sun}_, down to the hydrogen burning mass-limit, M_HB_~0.07M_{sun}_. The stars were detected by the WASP survey for transiting extra-solar planets, as low-mass, eclipsing companions orbiting more massive, F- and G-type host stars. We use eclipse observations of the host stars, performed with the TRAPPIST, Leonhard Euler and SPECULOOS telescopes, and radial velocities of the host stars obtained with the CORALIE spectrograph, to determine the physical properties of the low-mass companions. Surface gravities of the low-mass companions are derived from the eclipse and orbital parameters of each system. Spectroscopic measurements of the host star effective temperature and metallicity are used to infer the host star mass and age from stellar evolution models for solar-type stars. Masses and radii of the low-mass companions are then derived from the eclipse and orbital parameters of the binary systems. The objects are compared to stellar evolution models for low-mass stars, to test for an effect of the stellar metallicity and orbital period on the radius of low-mass stars in close binary systems. Measurements are found to be in good agreement with stellar evolution models; a systematic inflation of the radius of low-mass stars with respect to model predictions is limited to 1.6+/-1.2%, in the fully convective low-mass regime. The sample of ten objects indicates a scaling of the radius of low-mass stars with the host star metallicity. No correlation between stellar radii and the orbital periods of the binary systems is determined. A combined analysis with thirteen comparable objects from the literature is consistent with this result.
- ID:
- ivo://CDS.VizieR/J/AcA/61/103
- Title:
- VI light curves of LMC eclipsing binaries
- Short Name:
- J/AcA/61/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 26121 visually inspected eclipsing binary stars identified in the Large Magellanic cloud during the third phase of the Optical Gravitational Lensing Experiment. the sample is limited to the out-of-eclipse brightness I<20mag. The catalog consist mostly of detached eclipsing binaries - ellipsoidal variables were not included.
- ID:
- ivo://CDS.VizieR/J/AJ/123/279
- Title:
- VI Photometry and Variables in NGC 3201
- Short Name:
- J/AJ/123/279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Globular Cluster NGC 3201 was monitored for the existence of variable stars with 16.5<V<20 and 0.2days<period<5days. The files v*.dat contain time-series photometry data in V and I for the 14 variables detected in the field of NGC 3201. Only V6 (a blue straggler contact binary) is a member of the cluster. Due to its low-latitude position, interstellar extinction is present across the field of the cluster. The file phot.dat contains VI photometry data on the monitored stars. These data are NOT corrected for extinction. The variables V7, V8, and V9 were discovered during a follow-up observing run with a different telescope and therefore do not lie in the field covered by phot.dat. Variables V1-V9 are contact system eclipsing binaries, V10 is an RR Lyrae, V11 a semi-detached Algol type binary, V12 a detached binary system, and V13 and V14 are unclassified variable systems.
