- ID:
- ivo://CDS.VizieR/J/PASP/125/126
- Title:
- Light curve of CR Boo over 1990-2012
- Short Name:
- J/PASP/125/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two telescopes are used at the Morgan-Monroe Observatory of Indiana University for autonomous long-term photometric monitoring of stellar sources, mostly cataclysmic variable stars. The instrumentation is designed and implemented to be appropriate for multiyear automated monitoring. The capabilities and limitations of the equipment are described, along with accounts of the software, the reduction procedures, the motivations for the scientific programs, and the execution of the observing campaigns. Data on the AM CVn-type cataclysmic variable CR Boo are presented and discussed as an example of the kinds of light curves generated at this facility. The He-rich disk in CR Boo has SU UMa-type outburst behavior, with both superoutbursts and what appear to be dwarf nova outbursts. However, the light curve is quite irregular and displays a wide variety of unusual features such as switching among several superoutburst recurrence intervals, and having intervals of dwarf nova-like outbursts that seem to come and go. We discuss the likelihood that deterministic chaos is responsible for these irregularities.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/486/891
- Title:
- Light curve of EROS2 J005135-714459
- Short Name:
- J/A+A/486/891
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For seven years, the EROS-2 project obtained a mass of photometric data on variable stars. We present a peculiar Cepheid-like star, in the direction of the Small Magellanic Cloud, which demonstrates unusual photometric behaviour over a short time interval.
3473. Light curve of HD 172189
- ID:
- ivo://CDS.VizieR/J/A+A/468/637
- Title:
- Light curve of HD 172189
- Short Name:
- J/A+A/468/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. We performed a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign. We have identified six pulsation frequencies with a 99% confidence level and a seventh with a 65% confidence level, in the range between 100-300uHz. In addition, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.
- ID:
- ivo://CDS.VizieR/J/AJ/147/105
- Title:
- Light curve of HR Lyr over 1991-2012
- Short Name:
- J/AJ/147/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ~0.6mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012+/-0.005mag/yr is apparent, consistent with the fading of irradiation-induced Mdot following the nova. The equivalent width of H{alpha} is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which H{alpha} was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A114
- Title:
- Light curve of K2-292 (HD 119130)
- Short Name:
- J/A+A/623/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery and characterisation of a new transiting planet from Campaign 17 of the Kepler extended mission K2. The planet K2-292 b is a warm sub-Neptune on a 17-d orbit around a bright (V=9.9mag) solar-like G3 V star with a mass and radius of Ms=1.00+/-0.03M_{sun}_ and Rs=1.09+/-0.03R_{sun}_ respectively. We model simultaneously the K2 photometry and CARMENES spectroscopic data and derive a radius of Rp=2.63_-0.10+^+0.12^R_{earth}_ and mass of Mp=24.5_-4.4_^+4.4^M_{earth}_, yielding a mean density of 7.4_-1.5_^+1.6^g/cm^3^, which makes it one of the densest sub-Neptune planets known to date. We also detect a linear trend in radial velocities of HD 119130 that suggests a long-period companion with a minimum mass on the order of 33M_{earth}_. If confirmed, it would support a formation scenario of K2-292 b by migration caused by Kozai-Lidov oscillations.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/1154
- Title:
- Light curve of 2MASS J05352184-0546085
- Short Name:
- J/ApJ/664/1154
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The newly discovered brown dwarf eclipsing binary 2MASS J05352184-0546085 provides a unique laboratory for testing the predictions of theoretical models of brown dwarf formation and evolution. The finding that the lower mass brown dwarf in this system is hotter than its higher mass companion represents a challenge to brown dwarf evolutionary models, none of which predict this behavior. Here we present updated determinations of the basic physical properties of 2M0535-05, bolstering the surprising reversal of temperatures with mass in this system. We compare these measurements with widely used brown dwarf evolutionary tracks, and find that the temperature reversal can be explained by some models if the components of 2M0535-05 are mildly non-coeval, possibly consistent with dynamical simulations of brown dwarf formation. Alternatively, a strong magnetic field on the higher mass brown dwarf might explain its anomalously low surface temperature, consistent with emerging evidence that convection is suppressed in magnetically active, low-mass stars. Finally, we discuss future observational and theoretical work needed to further characterize and understand this benchmark system.
- ID:
- ivo://CDS.VizieR/J/AJ/159/256
- Title:
- Light curve of OGLE-2018-BLG-0677
- Short Name:
- J/AJ/159/256
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We report the analysis of the microlensing event OGLE-2018-BLG-0677. A small feature in the light curve of the event leads to the discovery that the lens is a star-planet system. Although there are two degenerate solutions that could not be distinguished for this event, both lead to a similar planet-host mass ratio. We perform a Bayesian analysis based on a Galactic model to obtain the properties of the system and find that the planet corresponds to a super- Earth/sub-Neptune with a mass of M_planet_=3.96_-2.66_^+5.88^M_{Earth}_. The host star has a mass of M_host_=0.12_-0.08_^+0.14^M_{odot}_. The projected separation for the inner and outer solutions are 0.63_-0.17_^+0.20^au and 0.72_-0.19_^+0.23^au respectively. At {Delta}{chi}^2^={chi}^2^(1L1S-{chi}^2^(2L1S)=46, this is by far the lowest {Delta}{chi}^2^ for any securely detected microlensing planet to date, a feature that is closely connected to the fact that it is detected primarily via a "dip" rather than a "bump."
3478. Light curve of R Cygni
- ID:
- ivo://CDS.VizieR/J/A+A/390/585
- Title:
- Light curve of R Cygni
- Short Name:
- J/A+A/390/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A detailed analysis of the century long visual light curve of the long-period Mira star R Cygni is presented and discussed. The data were collected from the publicly available databases of the AFOEV, the BAAVSS and the VSOLJ. The full light curve consists of 26655 individual points obtained between 1901 and 2001. The light curve and its periodicity were analysed with help of the O-C diagram, Fourier analysis and time-frequency analysis. The results demonstrate the limitations of these linear methods. The next step was to investigate the possible presence of low-dimensional chaos in the light curve. For this, a smoothed and noise-filtered signal was created from the averaged data and with the help of time delay embedding, we have tried to reconstruct the attractor of the system. The main result is that R Cygni shows such period-doubling events that can be interpreted as being caused by a repetitive bifurcation of the chaotic attractor between a period 2T orbit and chaos. The switch between these two states occurs in a certain compact region of the phase space, where the light curve is characterized by ~1500-day long transients. The Lyapunov spectrum was computed for various embedding parameters confirming the chaotic attractor, although the exponents suffer from quite high uncertainty because of the applied approximation. Finally, the light curve is compared with a simple one zone model generated by a third-order differential equation which exhibits well-expressed period-doubling bifurcation. The strong resemblance is another argument for chaotic behaviour. Further studies should address the problem of global flow reconstruction, including the determination of the accurate Lyapunov exponents and dimension.
- ID:
- ivo://CDS.VizieR/J/AJ/161/15
- Title:
- Light curve of the dwarf nova AT 2020iko
- Short Name:
- J/AJ/161/15
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- The ongoing Zwicky Transient Facility (ZTF) survey is generating a massive alert rate from a variety of optical transients and variable stars, which are being filtered down to subsets meeting user-specified criteria by broker systems such as the Arizona-NOIRLab Temporal Analysis and Response to Events System (ANTARES). In a beta implementation of the algorithm of Soraisam et al. on ANTARES, we flagged AT 2020iko from the ZTF real-time alert stream as an anomalous source. This source is located close to a red extended Sloan Digital Sky Survey source. In the first few epochs of detection, it exhibited a V-shaped brightness profile, preceded by nondetections both in ZTF and in the All-Sky Automated Survey for Supernovae extending to 2014. Its full light curve shows a precursor event, followed by a main superoutburst and at least two rebrightenings. A low-resolution spectrum of this source points to a dwarf nova (DN) nature. Although some of the features of AT 2020iko indicate an SU UMa-type DN, its large amplitude, presence of rebrightenings, and inferred supercycle period of >~6yr are in favor of AT 2020iko being a new WZ Sge- type DN candidate, a subset of rare DNe consisting of extreme mass-ratio (<0.1) binaries with an orbital period around the period minimum. The precusor event of AT 2020iko brightened by 6.5mag, while its decay spanned 3-5mag. We speculate this superoutburst is associated with a less expanded accretion disk than in typical superoutbursts in WZ Sge systems, with the large depth of the precursor decay implying an extremely small mass ratio. To the best of our knowledge, such a precursor event has not been recorded for any DN. This result serves to demonstrate the efficacy of our real-time anomaly search algorithm.
- ID:
- ivo://CDS.VizieR/J/ApJ/718/1353
- Title:
- Light curve of the triple system NLTT 41135
- Short Name:
- J/ApJ/718/1353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of an eclipsing companion to NLTT 41135, a nearby M5 dwarf that was already known to have a wider, slightly more massive common proper motion companion, NLTT 41136, at 2.4" separation. Analysis of combined-light and RV curves of the system indicates that NLTT 41135B is a (31-34)+/-3M_Jup_ brown dwarf (where the range depends on the unknown metallicity of the host star) on a circular orbit. The visual M dwarf pair appears to be physically bound, so the system forms a hierarchical triple, with masses approximately in the ratio 8:6:1. The eclipses are grazing, preventing an unambiguous measurement of the secondary radius, but follow-up observations of the secondary eclipse (e.g., with the James Webb Space Telescope) could permit measurements of the surface brightness ratio between the two objects, and thus place constraints on models of brown dwarfs.
