- ID:
- ivo://CDS.VizieR/J/ApJ/889/148
- Title:
- V346 Nor IJHKs photometry & IR spectra
- Short Name:
- J/ApJ/889/148
- Date:
- 17 Jan 2022 11:51:03
- Publisher:
- CDS
- Description:
- FU Orionis-type objects (FUors) are young low-mass stars undergoing powerful accretion outbursts. The increased accretion is often accompanied by collimated jets and energetic, large-scale molecular outflows. The extra heating during the outburst may also induce detectable geometrical, chemical, and mineralogical changes in the circumstellar material, affecting possible planet formation around these objects. V346 Nor is a southern FUor with peculiar spectral characteristics. Decades after the beginning of its outburst, it unexpectedly underwent a fading event around 2010 due to a decrease in the mass accretion rate onto the star by at least two orders of magnitude. Here we present optical and near-infrared photometry and spectroscopy obtained after the minimum. Our light curves show a gradual re-brightening of V346 Nor, with its Ks-band brightness only 1.5mag below the outburst brightness level. Our Very Large Telescope (VLT)/XSHOOTER spectroscopic observations display several strong forbidden emission lines toward the source from various metals and molecular hydrogen, suggesting the launch of a new jet. Our N-band spectrum obtained with VLT/VISIR outlines a deeper silicate absorption feature than before, indicating that the geometry of the circumstellar medium has changed in the post-outburst period compared to peak brightness.
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- ID:
- ivo://CDS.VizieR/J/A+A/511/A63
- Title:
- V1118 Ori UBVRIJHK outburst light curves
- Short Name:
- J/A+A/511/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The accretion history of low-mass young stars is not smooth but shows spikes of accretion that can last from months and years to decades and centuries. Observations of young stars in outbursts can help us understand the temporal evolution of accreting stars and the interplay between the accretion disk and the stellar magnetosphere. The young late-type star V1118 Orionis was in outburst from 2005 to 2006. We followed the outburst with optical and near-infrared photometry. The X-ray emission was further probed with observations taken with XMM-Newton and Chandra during and after the outburst. In addition, we obtained mid-infrared photometry and spectroscopy with Spitzer at the peak of the outburst and in the post-outburst phase. The spectral energy distribution of V1118 Ori varied significantly over the course of the outburst. The optical flux showed the largest variations, most likely caused by enhanced emission by a hot spot. The hot spot dominated the optical and near-infrared emission at the peak of the outburst, while the disk emission dominated in the mid-infrared. The emission silicate feature in V1118 Ori is flat and does not vary in shape, but was slightly brighter at the peak of the outburst compared to the post-outburst spectrum. The X-ray flux correlated with the optical and infrared fluxes, indicating that accretion affected the magnetically active corona and the stellar magnetosphere. The thermal structure of the corona was variable with some indication of a cooling of the coronal temperature in the early phase of the outburst with a gradual return to normal values. Color-color diagrams in the optical and infrared showed variations during the outburst, with no obvious signature of reddening caused by circumstellar matter. Using Monte-Carlo realizations of star+disk+hotspot models to fit the spectral energy distributions in "quiescence" and at the peak of the outburst, we determined that the mass accretion rate varied from about 2.5x10^-7^M_{sun}_/yr to 1.0x10^-6^M_{sun}_/yr; in addition, the fractional area of the hotspot increased significantly. The multi-wavelength study of the V1118 Ori outburst helped us to understand the variations in spectral energy distributions and demonstrated the interplay between the disk and the stellar magnetosphere in a young, strongly accreting star.
1633. V1162 Ori variations
- ID:
- ivo://CDS.VizieR/J/A+A/374/1056
- Title:
- V1162 Ori variations
- Short Name:
- J/A+A/374/1056
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V1162 Ori is a delta Scuti star with variable period and amplitude. To analyse data acquired in the years 1998-2000, the data were subdivided in smaller subsets to take the amplitude and period variability into account. Four different ways of subdividing the data discussed in the paper are outlined in this table 2. A database containing the observations of V1162 Ori is in preparation; it will be published in the Journal of Astronomical data (http://www.vub.ac.be/STER/JAD/jad.htm).
- 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.
- 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.
