- ID:
- ivo://CDS.VizieR/J/PAZh/35/199
- Title:
- V,pg light curves of NSV 9159
- Short Name:
- J/PAZh/35/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained 530 photographic magnitude estimates for the long-period classical Cepheid NSV 9159 (P=39d) in the plate collections of the Harvard Observatory and the Sternberg Astronomical Institute. Together with the currently available CCD observations from the ASAS-3 catalog, our data have allowed us to construct an O-C diagram spanning a time interval of 119 years. The O-C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary decrease in the period, 314.4(+/-7.3)s/yr, in agreement with the results of theoretical calculations for the second crossing of the instability strip. The available data reduced by the Eddington-Plakidis method do not reveal any noticeable random fluctuations in the period.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/370/1429
- Title:
- V photometry of bright stars of M33
- Short Name:
- J/MNRAS/370/1429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a long-term V-band photometric monitoring of M33 on 95 nights during four observing seasons (2000-2003). A total number of 6418 light curves of bright objects in the range of 14-21mag have been obtained. All measurements are publicly available. A total of 127 new variables were detected, of which 28 are periodic. 10 previously known non-periodic variables were identified as periodic, three of which are Cepheids, and another previously known periodic variable was identified as an eclipsing binary. Our derived periods range from 2.11 to almost 300d. For 50 variables we have combined our observations with those of the DIRECT project, obtaining light curves of up to 500 measurements, with a time-span of ~7yr. We have detected a few interesting variables, including a 99.3d periodic variable with a 0.04mag amplitude, at the position of supernova remnant (SNR) 19.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A135
- Title:
- V646 Pup TESS and ground photometry and spectrum
- Short Name:
- J/A+A/644/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate small-scale light variations in V646 Pup occurring in the timescales of days, weeks and years. To check if this variability is similar to that observed in FU Ori. We observed V646 Pup on six occasions at the SAAO and CTIO during 2013-2018 in Johnson and Sloan filters, typically with 1 d cadence maintained for 2-4 weeks. We also utilise the public-domain 1512 day long ASAS-SN light curve and TESS photometry obtained in 2019 during 24.1 days with 30 min cadence. New SAAO low-resolution spectra help to update major disc parameters, while the archival high-resolution Keck spectra are used to search for temporal changes in the disc rotational profiles. The ground-based observations confirm the constantly decreasing brightness of V646 Pup at the rate of 0.018mag per year. Precise i-band sensitive TESS data show that the little 0.005-0.01mag light variations imposed on this general trend do consist of a few independent wave trains of apparently time-coherent nature. Assuming that this is typical situation, from analysis of colour-magnitude diagrams obtained on earlier epochs we preliminarily inferred that the bulk of observed light changes could be owing to rotation of disc photosphere inhomogeneities, arising between 10-12 solar radii from the star. It is not excluded that these inhomogeneities could also manifest themselves in rotational profiles of the disc, as obtained from the high-resolution spectra. Assuming Keplerian rotation of these inhomogeneities, we preliminarily determine the stellar mass at 0.7-0.9 solar masses. At least during certain weeks V646 Pup shows time-coherent light variability pattern(s) that could be explained by rotation of an inhomogeneous disc photosphere. These preliminary results are similar to those better established for FU Ori, what suggests a common driving mechanism(s).
- ID:
- ivo://CDS.VizieR/J/AJ/158/51
- Title:
- VR CCD photometry of variable stars in the GC NGC 4147
- Short Name:
- J/AJ/158/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for variable stars in a region of the globular cluster NGC 4147 based on photometric observations with a 4Kx4K CCD imager mounted at the axial port of the recently installed 3.6 m Devasthal optical telescope (DOT) at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, India. We performed time series photometry of NGC 4147 in the V and R bands, and identified 42 periodic variables in the region of NGC 4147, 28 of which have been detected for the first time. Seventeen variable stars are located within the half-light radius ~<0.48', of which 10 stars are newly identified variables. Two of the 10 variables are located within the core radius ~<0.09'. Based on their location in the V/(V-R) color-magnitude diagram and variability characteristics, seven, eight, five, and one newly identified probable member variables are classified as RRc, EA/E, EW, and SX Phe, respectively. The metallicity of NGC 4147 estimated from the light curves of RRab and RRc stars with the help of Fourier decomposition is found to be characteristic of Oosterhoff II. The distance derived using the light curves of RRab stars is consistent with that obtained from the observed V/(V-R) color-magnitude diagram.
- ID:
- ivo://CDS.VizieR/J/MNRAS/330/137
- Title:
- VRc observations of LMC long-period red variables
- Short Name:
- J/MNRAS/330/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 146 long-period red variable stars in the Large Magellanic Cloud (LMC) from the three-year Microlensing Observations in Astrophysics (MOA) project data base were analysed. A careful periodic analysis was performed on these stars and a catalogue of their magnitudes, colours, periods and amplitudes is presented. We convert our blue and red magnitudes to K-band values using 19 oxygen-rich stars. A group of red short-period stars separated from the Mira sequence has been found on a (log P,K) diagram. They are located at the short period side of the Mira sequence consistent with the work of Wood & Sebo (1996MNRAS.282..958W). There are two interpretations for such stars; a difference in pulsation mode or a difference in chemical composition. We investigated the properties of these stars together with their colour, amplitude and periodicity. We conclude that they have small amplitudes and less regular variability. They are likely to be higher-mode pulsators. A large scatter has also been found on the long-period side of the (logP,K) diagram. This is possibly a systematic spread given that the blue band of our photometric system covers both standard B and V bands and affects carbon-rich stars.
- ID:
- ivo://CDS.VizieR/J/A+A/410/879
- Title:
- VRI CCD photometry of NGC 2126
- Short Name:
- J/A+A/410/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first CCD photometric observations of the northern open cluster NGC 2126. Data were taken on eight nights in February and December 2002 with a total time span of ~57 hours. Almost 1000 individual V-band frames were examined to find short-period variable stars. We discovered six new variable stars, of which one is a promising candidate for an eclipsing binary with a pulsating component. Here we present single-epoch colours and magnitudes for ~800 stars in the field and the light curve data for the six variables. Note that the coordinates in ngc2126.dat are not particularly accurate because of the applied crude astrometry (errors up to +/-1-2arcsec are quite likely close to the edge). For variable star identification, consult table3.dat.
- ID:
- ivo://CDS.VizieR/J/PASP/111/812
- Title:
- V(RI)C Phot of Cepheids in the Magellanic Clouds
- Short Name:
- J/PASP/111/812
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present V(RI)C data for 13 Cepheids in the Large Magellanic Cloud and eight in the Small Magellanic Cloud. The total number of new measures is 55 in each wavelength band. The median uncertainty in the photometry is 0.03 mag. These results supplement a larger photometric program presented in the second paper in this series which contained 1000 measures (0.01 mag) in each wavelength band on 22 variables with periods in the range 8133 days.
- ID:
- ivo://CDS.VizieR/J/A+A/430/1005
- Title:
- VRIH{alpha} photometry of NGC 2264 variables
- Short Name:
- J/A+A/430/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 1 lists 405 periodic variable stars we found in the area of NGC 2264 between. It contains information of the position, brightness, colours, and period of these stars. It also lists the spectral type taken from the literature (if available) as well as the alternative identification numbers of the stars which we used in the analysis process. The results presented here are based on a photometric monitoring program of a 34'x34' field in NGC 2264 carried out with the Wide-Field-Imager (WFI) attached to the ESO/MPG 2.2m telescope on La Silla, Chile. Observations were obtained on 44 nights in the I_C_ band during a period of two months between Dec. 2000 and March 2001. We also obtained several additional images through V, R_C_ and H{alpha} filters.
- ID:
- ivo://CDS.VizieR/J/AJ/159/135
- Title:
- VRIJHK LCs of the binary T Tauri star V582 Mon
- Short Name:
- J/AJ/159/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The binary T Tauri star V582Mon (KH15D) is surrounded by a tilted and nodally precessing ring of dusty material, which has caused periodic occultations of one or both stars over the last 50 years. Here, we present multi-color time-series photometry (VRIJHK) throughout the 2017/2018 observing season, when the ring was covering the entire orbit of star A and gradually exposing the orbit of star B. We calculate the mean apparent magnitude of star B to be I=14.08. Besides the periodic eclipses of star B due to its orbital motion, we observed unexpected dips in brightness indicative of partially transparent stellar-sized clumps within the ring. The wavelength dependence of these events is suggestive of extinction by dust grains significantly larger than typical interstellar dust grains. The photometric variability observed while star B is being uncovered by the trailing edge of the ring is not simply the time reversal of the behavior seen when star A was being covered by the leading edge. Whereas the leading edge appeared to be very sharply defined, the trailing edge is "clumpy" and "fuzzy" (transparent), with a more gradual transition in opacity. The clumpiness and transparency of the occulting material provide a unique opportunity to study the properties of dust grains in a likely planet-forming zone.
- ID:
- ivo://CDS.VizieR/J/AJ/155/47
- Title:
- VRIJHK photometry of the T Tauri binary KH 15D
- Short Name:
- J/AJ/155/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRIJHK photometry of the KH 15D T Tauri binary system for the 2015/2016 and 2016/2017 observing seasons. For the first time in the modern (CCD) era, we are seeing Star B fully emerge from behind the trailing edge of the precessing circumbinary ring during each apastron passage. We are, therefore, able to measure its luminosity and color. Decades of photometry on the system now allow us to infer the effective temperature, radius, mass, and age of each binary component. We find our values to be in good agreement with previous studies, including archival photographic photometry from the era when both stars were fully visible, and they set the stage for a full model of the system that can be constructed once radial velocity measurements are available. We also present the first high-sensitivity radio observations of the system, taken with the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array. The respective 2.0 and 0.88 mm observations provide an upper limit on the circumbinary (gas and dust) disk mass of 1.7 M_Jup_ and reveal an extended CO outflow, which overlaps with the position, systemic velocity, and orientation of the KH 15D system and is certainly associated with it. The low velocity, tight collimation, and extended nature of the emission suggest that the outflow is inclined nearly orthogonal to the line of sight, implying it is also orthogonal to the circumbinary ring. The position angle of the radio outflow also agrees precisely with the direction of polarization of the optical emission during the faint phase. A small offset between the optical image of the binary and the central line of the CO outflow remains a puzzle and possible clue to the jet launching mechanism.
