- ID:
- ivo://CDS.VizieR/J/AJ/144/50
- Title:
- Light curves of AV Hya and DZ Cas
- Short Name:
- J/AJ/144/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present BVR photometric observations and several eclipsing times for AV Hya and DZ Cas from 2004 to 2011. Using the Wilson-Devinney method, the photometric solutions with hot spots were deduced from their asymmetric light curves. The results indicate that both stars are Algol-type binaries, whose mass ratio, q_ph_, and fill-out factor of the primary, f_1_, are q_ph_=0.255(+/-0.002) and f_1_=81.2(+/-0.2)% for AV Hya, and q_ph_=0.093(+/-0.003) and f_1_=98.7(+/-0.3)% for DZ Cas. Based on all available light minimum times, it is discovered that the O-C curve of each star could be described by a light-time orbit overlying on a downward parabola. Their periods and amplitudes are P_3_=37.2(+/-0.7)yr and A=0.0095'(+/-0.0006') for AV Hya, and P_3_=62.5(+/-1.0)yr and A=0.0183'(+/-0.0007') for DZ Cas. Cyclic variations may result from the light-time effect due to the third body. The secular period decrease rates are dP/dt=-1.47(+/-0.04)x10^-7^days/yr for AV Hya and dP/dt=-0.92(+/-0.04)x10^-7^days/yr for DZ Cas. This may be interpreted using mass and angular momentum loss from the system. With decreasing period, the fill-out factor of the primary increases and it may finally fill its inner Roche lobe. Therefore, AV Hya and DZ Cas with a secular period decrease will evolve from semi-detached configurations into contact ones.
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- ID:
- ivo://CDS.VizieR/J/A+A/456/599
- Title:
- Light curves of 5 cataclysmic variables
- Short Name:
- J/A+A/456/599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-resolved photometry of five relatively poorly-studied cataclysmic variables: V1193 Ori, LQ Peg, LD 317, V795 Her and MCT 2347-3144. The observations were made using four 1m-class telescopes for a total of more than 250h of observation and almost 16,000 data points. For LQ Peg WHT spectroscopic data have been analysed as well. The light curves show a whole range of variability on different time scales, from minutes to months. We detect for the first time a brightness variation of 0.05mag in amplitude in V1193 Ori on the same timescale as the orbital period, that we interpret as the result of the irradiation of the secondary. A 20-min Quasi-Periodic Oscillation is also detected. The mean brightness of the system has changed by 0.5mag on a three month interval, while the flickering was halved. In LQ Peg a 0.05mag modulation was revealed with a period of about 3h. The flickering was much smaller, of the order of 0.025mag. A possible Quasi-Periodic Oscillation could exist near 30min. For this object, the WHT spectra are single peaked and do not show any radial-velocity variations. The data of LD 317 show a decrease in the mean magnitude of the system. No periodic signal was detected but this is certainly attributable to the very large flickering observed: between 0.07 and 0.1mag. For V795 Her, the 2.8-hour modulation, thought to be a superhump arising from the precession of the disc, is present. We show this modulation not to be stable in terms of periodicity, amplitude and phase. Finally, for MCT 2347-3144, a clear modulation is seen in a first dataset obtained in October 2002. This modulation is absent in August 2003, when the system was brighter and showed much more flickering.
- ID:
- ivo://CDS.VizieR/J/A+A/507/495
- Title:
- Light curves of Datura and 2003 CL5 asteroids
- Short Name:
- J/A+A/507/495
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Research of asteroid families has been recently refreshed by the discovery of very young ones. These families are of great interest because they represent the product of their parent body fragmentation before orbital and physical evolutionary processes can change them. A cluster of seven objects around the largest body (1270) Datura is of particular interest because it has enough known members and resides in the inner part of the main asteroid belt, facilitating observations. We carried out photometric observations of the two largest members of the Datura family - asteroids (1270) Datura and (90265) 2003 CL5 - with the goal of inferring their physical parameters. We also used numerous astrometric observations of Datura-family members in the past few years to revisit the age of this cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A2
- Title:
- Light curves of DP CVn and DI Psc
- Short Name:
- J/A+A/551/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first Doppler imaging study of the two rapidly rotating, single K-giants DP CVn and DI Psc in order to study the surface spot configuration and to pinpoint their stellar evolutionary status. Optical spectroscopy and photometry are used to determine the fundamental astrophysical properties. Doppler imaging is applied to recover the surface temperature distribution for both stars, while photometric light-curve inversions are carried out for studying the long-term changes of the surface activity of DP CVn. Surface differential rotation of DP CVn is estimated from cross-correlating the available subsequent Doppler reconstructions separated by roughly one rotation period. Both stars appear to have higher than normal lithium abundance, LTE logn of 2.28 (DP CVn) and 2.20 (DI Psc), and are supposed to be located at the end of the first Li dredge-up on the RGB. Photometric observations reveal rotational modulation with a period of 14.010d (DP CVn) and 18.066d (DI Psc). Doppler reconstructions from the available mapping lines well agree in the revealed spot patterns, recovering rather low latitude spots for both stars with temperature contrasts of {DELTA}T~600-800K below the unspotted photospheric background. Spots at higher latitudes are also found but either with less contrast (DP CVn) or with smaller extent (DI Psc). A preliminary antisolar-type differential rotation with {alpha}=-0.035 is found for DP CVn from cross-correlating the subsequent Doppler images. Long-term photometric analysis supports the existence of active longitudes, as well as the differential rotation.
- ID:
- ivo://CDS.VizieR/J/AJ/134/787
- Title:
- Light curves of dwarf plutonian planets
- Short Name:
- J/AJ/134/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I report new time-resolved light curves and determine the rotations and phase functions of several large Kuiper Belt objects, which includes the dwarf planet Eris (2003 UB313). Three of the new sample of 10 trans-Neptunian objects display obvious short-term periodic light curves.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A72
- Title:
- Light curves of Flora region asteroids
- Short Name:
- J/A+A/546/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies have uncovered evidence that the statistical properties of asteroids' physical parameters are a fundamental source of information on the physics of their collisions and evolution. The analysis of the spin rates and spin vector distributions helps us to understand the role of various known and new effects. The alignment of spin vectors and the correlation of spin rates are for the first time observed for ten members of the Koronis family. These unexpected non-random orientations of the spin axes and correlations of the spin rates, now known as Slivan states are interpreted in terms of a YORP effect and spin-orbit resonances. To study non-gravitational-effects, there appears to be a need for new observational campaigns devoted to determining the physical parameters of the asteroid families. We analysed the photometric observations of the asteroids, which are the most efficient method of studying asteroid physical parameters.
- ID:
- ivo://CDS.VizieR/J/AJ/148/126
- Title:
- Light curves of four overcontact binaries
- Short Name:
- J/AJ/148/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze new, high quality multicolor light curves of four overcontact binaries: AK Her, HI Dra, V1128 Tau, and V2612 Oph, and determine their orbital and physical parameters using the modeling program of G. Djurasevic and recently published results of radial velocity studies. The achieved precision in absolute masses is between 10% and 20%, and the precision in absolute radii is between 5% and 10%. All four systems are W UMa-type binaries with bright or dark spots indicative of mass and energy transfer or surface activity. We estimate the distances and the ages of the systems using the luminosities computed through our analysis, and perform an O-C study for V1128 Tau, which reveals a complex period variation that can be interpreted in terms of mass loss/exchange and either the presence of the third body, or the magnetic activity on one of the components. We conclude that further observations of these systems are needed to deepen our understanding of their nature and variability.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/35
- Title:
- Light curves of four transients from PTF & SNLS
- Short Name:
- J/ApJ/819/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observations of four rapidly rising (t_rise_~10days) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M_peak_~-20) --one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey (SNLS). The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma-ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as an SN II due to broad H{alpha} emission, but an unusual absorption feature, which can be interpreted as either high velocity H{alpha} (though deeper than in previously known cases) or SiII (as seen in SNe Ia), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM), and magnetar spin down cannot readily explain the observations. We consider the possibility that a "Type 1.5 SN" scenario could be the origin of our events.
3519. Light curves of GJ3470b
- ID:
- ivo://CDS.VizieR/J/A+A/559/A32
- Title:
- Light curves of GJ3470b
- Short Name:
- J/A+A/559/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a nearby M1.5 dwarf. It is crucial for atmospheric studies because it is one of the most inflated low-mass planets known, bridging the boundary between "super-Earths" and Neptunian planets. We present two new ground-based light curves of GJ3470b gathered by the LBC camera at the Large Binocular Telescope. Simultaneous photometry in the ultraviolet ({lambda}_c_=357.5nm) and optical infrared ({lambda}_c_=963.5nm) allowed us to detect a significant change in the effective radius of GJ3470b as a function of wavelength. This can be interpreted as a signature of scattering processes occurring in the planetary atmosphere, which should be cloud-free and with a low mean molecular weight. The unprecedented accuracy of our measurements demonstrates that the photometric detection of Earth-sized planets around M dwarfs is achievable using 8-10m size ground-based telescopes. We provide updated planetary parameters and a greatly improved orbital ephemeris for any forthcoming study of this planet.
- ID:
- ivo://CDS.VizieR/J/AJ/145/60
- Title:
- Light curves of GN Boo, BL Leo, and V1918 Cyg
- Short Name:
- J/AJ/145/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometry for three short-period contact binaries, GN Boo, BL Leo, and V1918 Cyg, observed from 2008 December to 2012 April using several small telescopes in China. Photometric models were deduced from new observations using the updated Wilson-Devinney Code. The results show that GN Boo and BL Leo are W-type contact binaries, while V1918 Cyg is an A-type one. The mass ratios and fill-out factors are q=0.320(+/-0.002) and f=5.8(+/-0.1)% for GN Boo, q=0.476(+/-0.005) and f=21.3(+/-1.1)% for BL Leo, q=0.264(+/-0.002), and f=49.7(+/-0.7)% for V1918 Cyg, respectively. From the (O-C) curves, it is discovered that the orbital periods of three binaries have varied in a complicated way, i.e., cyclic oscillation for GN Boo, long-term period decrease for BL Leo, and both for V1918 Cyg. The cyclic variations for GN Boo and V1918 Cyg may probably be attributed to the magnetic activity of the primary component or light-time effect due to the third body. Meanwhile, the secular period decreases for BL Leo and V1918 Cyg may result from mass transfer from the primary to the secondary, accompanying the mass and angular momentum loss from the central system. Finally, GN Boo, BL Leo, and V1918 Cyg will evolve into deep contact binaries. Additionally, a statistical study of 37 contact binaries with decreasing periods is given. We obtained the relations of q-f and q-dlnP/dt, and preliminarily determined the mass loss rate of dln M/dt from the binary system.
