The Penn State - Toru\'n Planet Search: target characteristics and recent results

More than 450 stars hosting planets are known today but only approximately 30 planetary systems were discovered around stars beyond the Main Sequence. The Penn State-Toru\'n Planet Search, putting an emphasis on extending studies of planetary system formation and evolution to intermediate-mass stars, is oriented towards the discoveries of substellar-mass companions to a large sample of evolved stars using high-precision radial velocity technique. We present the recent status of our survey and detailed characteristic for ~350 late type giant stars, i.e. the new results of radial velocity analysis and stellar fundamental parameters obtained with extensive spectroscopic method. Moreover, in the future we will make an attempt to perform the statistical study of our sample and searching the correlations between the existence of substellar objects and stellar atmospheric parameters according to previous works which investigated the planetary companion impact on the evolution of the host stars.Comment: 7 pages, 5 figures, proceeding of the conference "Planetary Systems beyond the Main Sequence" (Bamberg, Germany, August 11-14, 2010) edited by S. Schuh, H. Drechsel and U. Heber, AIP Conference Series, part of PlanetsbeyondMS/2010 proceedings http://arxiv.org/html/1011.660

Planets Around the K-Giants BD+20 274 and HD 219415

We present the discovery of planet-mass companions to two giant stars by the ongoing Penn State- Toru\'n Planet Search (PTPS) conducted with the 9.2 m Hobby-Eberly Telescope. The less massive of these stars, K5-giant BD+20 274, has a 4.2 MJ minimum mass planet orbiting the star at a 578-day period and a more distant, likely stellar-mass companion. The best currently available model of the planet orbiting the K0-giant HD 219415 points to a Jupiter-mass companion in a 5.7-year, eccentric orbit around the star, making it the longest period planet yet detected by our survey. This planet has an amplitude of \sim18 m/s, comparable to the median radial velocity (RV) "jitter", typical of giant stars.Comment: 5 figures, 13 pages, accepted by the Astrophysical Journal. arXiv admin note: substantial text overlap with arXiv:1110.164

A ROSAT Survey of Contact Binary Stars

Contact binary stars are common variable stars which are all believed to emit relatively large fluxes of x-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with x-ray data from the ROSAT All-Sky Survey (RASS) to estimate the x-ray volume emissivity of contact binary stars in the galaxy. We obtained x-ray fluxes for 140 contact binaries from the RASS, as well as 2 additional stars observed by the XMM-Newton observatory. From these data we confirm the emission of x-rays from all contact binary systems, with typical luminosities of approximately 1.0 x 10^30 erg s^-1. Combining calculated luminosities with an estimated contact binary space density, we find that contact binaries do not have strong enough x-ray emission to account for a significant portion of the galactic x-ray background.Comment: 19 pages, 5 figures, accepted by A

A Catalog of 1022 Bright Contact Binary Stars

In this work we describe a large new sample of contact binary stars extracted in a uniform manner from sky patrol data taken by the ROTSE-I telescope. Extensive ROTSE-I light curve data is combined with J, H, and K band near-infrared data taken from the Two Micron All-Sky Survey (2MASS) to add color information. Contact binaries candidates are selected using the observed period-color relation. Candidates are confirmed by visual examination of the light curves. To enhance the utility of this catalog, we derive a new J-H period-color-luminosity relation and use this to estimate distances for the entire catalog. From these distance estimates we derive an estimated contact binary space density of (1.7 +/- 0.6) x 10^-5 pcs^-3.Comment: 26 pages, 12 figures, accepted for publication in A

The potential importance of soil denitrification as a major N loss pathway in intensive greenhouse vegetable production systems

Background About 30 % of vegetables in China are produced in intensively managed greenhouses comprising flood irrigation and extreme rates of nitrogen fertilizers. Little is known about denitrification N losses. Methods Soil denitrification rates were measured by the acetylene inhibition technique applied to anaerobically incubated soil samples. Four different greenhouse management systems were differentiated: Conventional flood irrigation and over-fertilization (CIF, 800 kg N ha$^{-1Zahl}$, 460 mm); CIF plus straw incorporation (CIF+S, 889 kg N ha$^{-1}$, 460 mm); Drip fertigation with reduced fertilizer application rates (DIF, 314 kg N ha$^{-1}$, 190 mm); DIF plus straw incorporation (DIF+S, 403 kg N ha$^{-1}$, 190 mm). Soil denitrification was measured on nine sampling dates during the growing season (Feb 2019-May 2019) for the top-/ subsoil (0 – 20/ 20- 40 cm) and on three sampling dates for deep soils (40-60/ 80-100 cm). Data was used to constrain N-input-output balances of the different vegetable production systems. Results Rates of denitrification were at least one magnitude higher in topsoil than in sub- and deep soils. Total seasonal denitrification N losses for the 0 – 40 cm soil layer ranged from 76 (DIF) to 422 kg N ha$^{-1}$ (CIF+S). Straw addition stimulated soil denitrification in top- and subsoil, but not in deep soil layers. Integrating our denitrification data (0-100 cm) with additional data on N leaching, N2O emissions, plant N uptake, and NH3 volatilization showed, that on average 50 % of added N fertilizers are lost due to denitrification. Conclusions Denitrification is likely the dominant environmental N loss pathway in greenhouse vegetable production systems. Reducing irrigation and fertilizer application rates while incorporating straw in soils allows the reduction of accumulated nitrate

High Fill-Out, Extreme Mass Ratio Overcontact Binary Systems. X. The new discovered binary XY Leonis Minoris

The new discovered short-period close binary star, XY LMi, was monitored photometrically since 2006. It is shown that the light curves are typical EW-type and show complete eclipses with an eclipse duration of about 80 minutes. By analyzing the complete B, V, R, and I light curves with the 2003 version of the W-D code, photometric solutions were determined. It is discovered that XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q=0.148 and a fill-out factor of f=74.1%, suggesting that it is on the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components are given. Based on our 19 epoches of eclipse times, it is found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt=-1.67\times10^{-7}\,days/year, which may be caused by the mass transfer from the primary to the secondary or/and angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaching the outer critical Roche Lobe.Comment: 19 pages, 4 figures, 9 table

The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet

Kepler-10b was the first rocky planet detected by the Kepler satellite and con- firmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was sta- tistically validated, but the radial velocities were only good enough to set an upper limit of 20 Mearth for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In to- tal, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determina- tion for Kepler-10b to 15%. With a mass of 3.33 +/- 0.49 Mearth and an updated radius of 1.47 +0.03 -0.02 Rearth, Kepler-10b has a density of 5.8 +/- 0.8 g cm-3, very close to the value -0.02 predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 +/- 1.9 Mearth and radius of 2.35 +0.09 -0.04 Rearth, -0.04 Kepler-10c has a density of 7.1 +/- 1.0 g cm-3. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.Comment: 44 pages, 8 figures, accepted for publication in Ap

Precision Astrometry of the Exoplanet Host Candidate GD 66

The potential existence of a giant planet orbiting within a few AU of a stellar remnant has profound implications for both the survival and possible regeneration of planets during post-main sequence stellar evolution. This paper reports Hubble Space Telescope Fine Guidance Sensor and U.S. Naval Observatory relative astrometry of GD 66, a white dwarf thought to harbor a giant planet between 2 and 3 AU based on stellar pulsation arrival times. Combined with existing infrared data, the precision measurements here rule out all stellar-mass and brown dwarf companions, implying that only a planet remains plausible, if orbital motion is indeed the cause of the variations in pulsation timing.Comment: 6 pages, 3 figures, 1 table, accepted to MNRA

Solubility of Rock in Steam Atmospheres of Planets

Extensive experimental studies show that all major rock-forming elements (e.g., Si, Mg, Fe, Ca, Al, Na, K) dissolve in steam to a greater or lesser extent. We use these results to compute chemical equilibrium abundances of rocky-element-bearing gases in steam atmospheres equilibrated with silicate magma oceans. Rocky elements partition into steam atmospheres as volatile hydroxide gases (e.g., Si(OH)4, Mg(OH)2, Fe(OH)2, Ni(OH)2, Al(OH)3, Ca(OH)2, NaOH, KOH) and via reaction with HF and HCl as volatile halide gases (e.g., NaCl, KCl, CaFOH, CaClOH, FAl(OH)2) in much larger amounts than expected from their vapor pressures over volatile-free solid or molten rock at high temperatures expected for steam atmospheres on the early Earth and hot rocky exoplanets. We quantitatively compute the extent of fractional vaporization by defining gas/magma distribution coefficients and show that Earth's subsolar Si/Mg ratio may be due to loss of a primordial steam atmosphere. We conclude that hot rocky exoplanets that are undergoing or have undergone escape of steam-bearing atmospheres may experience fractional vaporization and loss of Si, Mg, Fe, Ni, Al, Ca, Na, and K. This loss can modify their bulk composition, density, heat balance, and interior structure

A 1.9 Earth Radius Rocky Planet and the Discovery of a Non-Transiting Planet in the Kepler-20 System*

Kepler-20 is a solar-type star (V = 12.5) hosting a compact system of five transiting planets, all packed within the orbital distance of Mercury in our own Solar System. A transition from rocky to gaseous planets with a planetary transition radius of ∼ 1.6 R⊕ has recently been proposed by several publications in the literature (Rogers 2015; Weiss& Marcy 2014). Kepler-20b (Rp ∼ 1.9 R⊕) has a size beyond this transition radius, however previous mass measurements were not sufficiently precise to allow definite conclusions to be drawn regarding its composition. We present new mass measurements of Kepler-20 three of the planets in the Kepler-20 system facilitated by 104 radial velocity measurements from the HARPS-N spectrograph and 30 archival Keck/HIRES observations, as well as an updated photometric analysis of the Kepler data and an asteroseismic analysis of the host star (M* = 0.948 ± 0.051 M☉ and R* = 0.964 ± 0.018 R☉).Kepler-20b is a 1.868+0.066 −0.034 R⊕ planet in a 3.7 day period with amass of 9.70+1.41 −1.44 M⊕ resulting in a mean density of 8.2 +1.5 −1.3 g cm−3 indicating a rocky composition with an iron to silicate ratio consistent with that of the Earth. This makes Kepler-20b the most massive planet with a rocky composition found to date. Furthermore, we report the discovery of an additional non-transiting planet with a minimum mass of 19.96+3.08 −3.61 M⊕ and an orbital period of ∼ 34 days in the gap between Kepler-20f (P ∼ 11 days) and Kepler-20d (P ∼78 days).PostprintPeer reviewe