- ID:
- ivo://CDS.VizieR/J/ApJ/785/15
- Title:
- Transit times for Kepler-79's known planets
- Short Name:
- J/ApJ/785/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-79 (KOI-152) has four planetary candidates ranging in size from 3.5 to 7 times the size of the Earth, in a compact configuration with orbital periods near a 1:2:4:6 chain of commensurability, from 13.5 to 81.1 days. All four planets exhibit transit timing variations with periods that are consistent with the distance of each planet to resonance with its neighbors. We perform a dynamical analysis of the system based on transit timing measurements over 1282 days of Kepler photometry. Stellar parameters are obtained using a combination of spectral classification and the stellar density constraints provided by light curve analysis and orbital eccentricity solutions from our dynamical study. Our models provide tight bounds on the masses of all four transiting bodies, demonstrating that they are planets and that they orbit the same star. All four of Kepler-79's transiting planets have low densities given their sizes, which is consistent with other studies of compact multiplanet transiting systems. The largest of the four, Kepler-79 d (KOI-152.01), has the lowest bulk density yet determined among sub-Saturn mass planets.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/501/4935
- Title:
- TYC 3700-1384-1, V1511 Her, V1179 Her minima
- Short Name:
- J/MNRAS/501/4935
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The first multi-colour light curve models and period studies for the totally eclipsing W UMa stars TYC 3700-1384-1, V1511 Her and V1179 Her are presented. All three stars are A-subtype W UMa stars of spectral type F. The light curve solutions show that TYC 3700-1384-1 has a moderately low mass ratio of q=0.182+/-0.001 and a degree of overcontact of f=49%. For V1179 Her a mass ratio q=0.153+/-0.001 and a degree of overcontact of f=48% is derived. The solution for V1511 Her is inconclusive, however the mass ratio is expected to be between 0.13<q<0.15. The evolutionary status is compared with zero-age main sequence stars taking into account energy transfer from the primary to the secondary component. The primary component of TYC 3700-1384-1 fits well in the main-sequence, while V1179 Her is more evolved. The period study reveals for all three stars a continuously increasing period at a rate of dP/dt=6.1x10^-7^d/yr, dP/dt=5.0x10^-7^d/yr and dP/dt=9.6x10^-7^d/yr for TYC 3700-1384-1, V1511 Her and V1179 Her respectively. The estimated mass transfer rates derived from these period changes are 1.6x10^-7^M_{sun}_/yr for TYC 3700-1384-1 and 1.9x10^-7^M_{sun}_/yr for V1179 Her.
- ID:
- ivo://CDS.VizieR/J/A+A/355/171
- Title:
- TZ Boo & Y Sex orbital periods
- Short Name:
- J/A+A/355/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- TZ Boo and Y Sex are two A-type contact binaries. At the set, times of light minimum of the two stars were collected.
- ID:
- ivo://CDS.VizieR/J/A+A/406/1135
- Title:
- UT1 definitions in IAU 2000
- Short Name:
- J/A+A/406/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper provides expressions to be used to implement the new definition of UT1 corresponding to the IAU 2000 resolutions either in the new (CEO-based) or classical (equinox-based) transformations between the International Terrestrial Reference System (ITRS) and the Geocentric Celestial Reference System (GCRS). The new expression for Greenwich Sidereal Time (GST) has to be in agreement at the micro-arcsecond level, for one century, with the IAU 2000 expressions for the Earth Rotation Angle (ERA) and for the quantity s positioning the Celestial Ephemeris Origin (CEO) on the equator of the CIP. The computations of the new expressions using the IAU 2000 precession-nutation model are performed in such a manner as to ensure that there is no discontinuity in UT1 on 1 January 2003 and that there is equivalence of the classical and new transformations between the ITRS and GCRS relative to the rotation about the axis of the CIP when these expressions are used. The equinox offset that is considered in the computations refers to the dynamical mean equinox of J2000.0. The resulting expressions have been included in the IERS Conventions 2000.
- ID:
- ivo://CDS.VizieR/J/MNRAS/484/3691
- Title:
- UTMOST pulsar timing programme. I.
- Short Name:
- J/MNRAS/484/3691
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview and the first results from a large-scale pulsar timing programme that is part of the UTMOST project at the refurbished Molonglo Observatory Synthesis Radio Telescope (MOST) near Canberra, Australia. We currently observe more than 400 mainly bright southern radio pulsars with up to daily cadences. For 205 (8 in binaries, 4 millisecond pulsars), we publish updated timing models, together with their flux densities, flux density variability, and pulse widths at 843 MHz, derived from observations spanning between 1.4 and 3 yr. In comparison with the ATNF pulsar catalogue, we improve the precision of the rotational and astrometric parameters for 123 pulsars, for 47 by at least an order of magnitude. The time spans between our measurements and those in the literature are up to 48 yr, which allow us to investigate their long-term spin-down history and to estimate proper motions for 60 pulsars, of which 24 are newly determined and most are major improvements. The results are consistent with interferometric measurements from the literature. A model with two Gaussian components centred at 139 and 463km/s fits the transverse velocity distribution best. The pulse duty cycle distributions at 50 and 10 per cent maximum are best described by lognormal distributions with medians of 2.3 and 4.4 per cent, respectively. We discuss two pulsars that exhibit spin-down rate changes and drifting subpulses. Finally, we describe the autonomous observing system and the dynamic scheduler that has increased the observing efficiency by a factor of 2-3 in comparison with static scheduling.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/1525
- Title:
- XMM-Newton and Chandra monitoring of Sgr A*
- Short Name:
- J/MNRAS/454/1525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the X-ray flaring activity of Sgr A* during all the 150 XMM-Newton and Chandra observations pointed at the Milky Way centre over the last 15 years. This includes the latest XMM-Newton and Chandra campaigns devoted to monitoring the closest approach of the very red Br{gamma} emitting object called G2. The entire data set analysed extends from 1999 September through 2014 November. We employed a Bayesian block analysis to investigate any possible variations in the characteristics (frequency, energetics, peak intensity, duration) of the flaring events that Sgr A* has exhibited since their discovery in 2001. We observe that the total bright or very bright flare luminosity of Sgr A* increased between 2013 and 2014 by a factor of 2-3 (~3.5{sigma} significance). We also observe an increase (~99.9 percent significance) from 0.27+/-0.04 to 2.5+/-1.0/d of the bright or very bright flaring rate of Sgr A*, starting in late summer 2014, which happens to be about six months after G2's pericentre passage. This might indicate that clustering is a general property of bright flares and that it is associated with a stationary noise process producing flares not uniformly distributed in time (similar to what is observed in other quiescent black holes). If so, the variation in flaring properties would be revealed only now because of the increased monitoring frequency. Alternatively, this may be the first sign of an excess accretion activity induced by the close passage of G2. More observations are necessary to distinguish between these two hypotheses.
