A Search for Planets with SALT

As the SALT High Resolution Spectrograph completion is nearing we plan to extend the Pennsylvania-Torun Planets Search (PTPS) with HET to the southern hemisphere. Due to overlap of the skies available for both HET and SALT in the declination range (+10, -10) deg some cooperation and immediate follow up is possible. Here we present, as an example, a $\sim$ 1000 star sample of evolved stars for the future SALT Planet Search.Comment: 6 pages, 2 figure

Red giants from the Pennsylvania - Torun Planet Search

The main goal of the Pennsylvania - Torun Planet Search (PTPS) is detection and characterization of planets around evolved stars using the high-accuracy radial velocity (RV) technique. The project is performed with the 9.2 m Hobby-Eberly Telescope. To determine stellar parameters and evolutionary status for targets observed within the survey complete spectral analysis of all objects is required. In this paper we present the atmospheric parameters (effective temperatures, surface gravities, microturbulent velocities and metallicities) of a subsample of Red Giant Clump stars using strictly spectroscopic methods based on analysis of equivalent widths of Fe I and Fe II lines. It is shown that our spectroscopic approach brings reliable and consistent results.Comment: 3 pages, 2 figures, proceeding of the conference "New Technologies for Probing the Diversity of Brown Dwarfs and Exoplanets" (Shangai, China, July 19-24, 2009), to appear in EPJ Web of Conference

The Penn State - Toru\'n Centre for Astronomy Planet Search stars IV. Dwarfs and the complete sample

Our knowledge of the intrinsic parameters of exoplanets is as precise as our determinations of their stellar hosts parameters. In the case of radial velocity searches for planets, stellar masses appear to be crucial. But before estimating stellar masses properly, detailed spectroscopic analysis is essential. With this paper we conclude a general spectroscopic description of the Pennsylvania-Torun Planet Search (PTPS) sample of stars. We aim at a detailed description of basic parameters of stars representing the complete PTPS sample. We present atmospheric and physical parameters for dwarf stars observed within the PTPS along with updated physical parameters for the remaining stars from this sample after the first Gaia data release. We used high resolution (R=60 000) and high signal-to-noise-ratio (S/N=150-250) spectra from the Hobby-Eberly Telescope and its High Resolution Spectrograph. Stellar atmospheric parameters were determined through a strictly spectroscopic local thermodynamic equilibrium analysis (LTE) of the equivalent widths of FeI and FeII lines. Stellar masses, ages, and luminosities were estimated through a Bayesian analysis of theoretical isochrones. We present $T_{eff}$, log$g$ , [Fe/H], micrturbulence velocities, absolute radial velocities, and rotational velocities for 156 stars from the dwarf sample of PTPS. For most of these stars these are the first determinations. We refine the definition of PTPS subsamples of stars (giants, subgiants, and dwarfs) and update the luminosity classes for all PTPS stars. Using available Gaia and Hipparcos parallaxes, we redetermine the stellar parameters (masses, radii, luminosities, and ages) for 451 PTPS stars. The complete PTPS sample of 885 stars is composed of 132 dwarfs, 238 subgiants, and 515 giants, of which the vast majority are of roughly solar mass.Comment: 11 pages, 10 figures, Accepted for publication in Astronomy & Astrophysic

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

Three red giants with substellar-mass companions

We present three giant stars from the ongoing Penn State-Toru\'n Planet Search with the Hobby-Eberly Telescope, which exhibit radial velocity variations that point to a presence of planetary --mass companions around them. BD+49 828 is a $M=1.52 \pm 0.22$ $M_{\odot}$ K0 giant with a $m sini$=$1.6^{+0.4}_{-0.2}$ $M_{J}$ minimum mass companion in $a=4.2^{+0.32}_{-0.2}$ AU ($2590^{+300}_{-180}$d), $e=0.35^{+0.24}_{-0.10}$ orbit. HD 95127, a log$L$/$L_{\odot}$=$2.28 \pm 0.38$, $R = 20\pm 9$ $R_{\odot}$, $M=1.20 \pm 0.22$ $M_{\odot}$ K0 giant has a $m sini$=$5.01^{+0.61}_{-0.44}$ $M_{J}$ minimum mass companion in $a=1.28^{+0.01}_{-0.01}$ AU ($482^{+5}_{-5}$d), $e=0.11^{+0.15}_{-0.06}$ orbit. Finally, HD 216536, is a $M=1.36 \pm 0.38$ $M_{\odot}$ K0 giant with a $m sin i=1.47^{+0.20}_{-0.12}$ $M_{J}$ minimum mass companion in $a=0.609^{+0.002}_{-0.002}$ AU ($148.6^{+0.7}_{-0.7}$d), $e=0.38^{+0.12}_{-0.10}$ orbit. Both, HD 95127 b and HD 216536 b in their compact orbits, are very close to the engulfment zone and hence prone to ingestion in the near future. BD+49 828 b is among the longest period planets detected with the radial velocity technique until now and it will remain unaffected by stellar evolution up to a very late stage of its host. We discuss general properties of planetary systems around evolved stars and planet survivability using existing data on exoplanets in more detail.Comment: 47 pages, 11 figures. Accepted by Ap

TAPAS - Tracking Advanced Planetary Systems with HARPS-N. II. Super Li-rich giant HD 107028

Lithium rich giant stars are rare objects. For some of them, Li enrichment exceeds abundance of this element found in solar system meteorites, suggesting that these stars have gone through a Li enhancement process. We identified a Li rich giant HD 107028 with A(Li) > 3.3 in a sample of evolved stars observed within the PennState Torun Planet Search. In this work we study different enhancement scenarios and we try to identify the one responsible for Li enrichment for HD 107028. We collected high resolution spectra with three different instruments, covering different spectral ranges. We determine stellar parameters and abundances of selected elements with both equivalent width measurements and analysis, and spectral synthesis. We also collected multi epoch high precision radial velocities in an attempt to detect a companion. Collected data show that HD 107028 is a star at the base of Red Giant Branch. Except for high Li abundance, we have not identified any other anomalies in its chemical composition, and there is no indication of a low mass or stellar companion. We exclude Li production at the Luminosity Function Bump on RGB, as the effective temperature and luminosity suggest that the evolutionary state is much earlier than RGB Bump. We also cannot confirm the Li enhancement by contamination, as we do not observe any anomalies that are associated with this scenario. After evaluating various scenarios of Li enhancement we conclude that the Li-overabundance of HD 107028 originates from Main Sequence evolution, and may be caused by diffusion process.Comment: Accepted for publication in A&

TAPAS IV. TYC 3667-1280-1 b - the most massive red giant star hosting a warm Jupiter

We present the latest result of the TAPAS project that is devoted to intense monitoring of planetary candidates that are identified within the PennState-Toru\'n planet search. We aim to detect planetary systems around evolved stars to be able to build sound statistics on the frequency and intrinsic nature of these systems, and to deliver in-depth studies of selected planetary systems with evidence of star-planet interaction processes. The paper is based on precise radial velocity measurements: 13 epochs collected over 1920 days with the Hobby-Eberly Telescope and its High-Resolution Spectrograph, and 22 epochs of ultra-precise HARPS-N data collected over 961 days. We present a warm-Jupiter ($T_{eq}=1350 K$, $m_{2} sin i=5.4\pm$0.4$M_{J}$) companion with an orbital period of 26.468 days in a circular ($e=0.036$) orbit around a giant evolved ($\log g=3.11\pm0.09$, $R=6.26\pm0.86R_{\odot}$) star with $M_{\star}=1.87\pm0.17M_{\odot}$. This is the most massive and oldest star found to be hosting a close-in giant planet. Its proximity to its host ($a=0.21au$) means that the planet has a $13.9\pm2.0\%$ probability of transits; this calls for photometric follow-up study. This massive warm Jupiter with a near circular orbit around an evolved massive star can help set constraints on general migration mechanisms for warm Jupiters and, given its high equilibrium temperature, can help test energy deposition models in hot Jupiters.Comment: 5 pages, 3 figures, accepted by A&

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. III. HD 5583 and BD+15 2375 - two cool giants with warm companions

Evolved stars are crucial pieces to understand the dependency of the planet formation mechanism on the stellar mass and to explore deeper the mechanism involved in star-planet interactions. Over the past ten years, we have monitored about 1000 evolved stars for radial velocity variations in search for low-mass companions under the Penn State - Torun Centre for Astronomy Planet Search program with the Hobby-Eberly Telescope. Selected prospective candidates that required higher RV precision measurements have been followed with HARPS-N at the 3.6 m Telescopio Nazionale Galileo under the TAPAS project. We aim to detect planetary systems around evolved stars to be able to build sound statistics on the frequency and intrinsic nature of these systems, and to deliver in-depth studies of selected planetary systems with evidence of star-planet interaction processes. For HD 5583 we obtained 14 epochs of precise RV measurements collected over 2313 days with the Hobby-Eberly Telescope (HET), and 22 epochs of ultra-precise HARPS-N data collected over 976 days. For BD+15 2375 we collected 24 epochs of HET data over 3286 days and 25 epochs of HARPS-S data over 902 days. We report the discovery of two planetary mass objects orbiting two evolved Red Giant stars: HD~5583 has a m sin i = 5.78 M$_{J}$ companion at 0.529~AU in a nearly circular orbit (e=0.076), the closest companion to a giant star detected with the RV technique, and BD+15~2735 that with a m sin i= 1.06 M$_{J}$ holds the record of the lightest planet found so far orbiting an evolved star (in a circular e=0.001, 0.576~AU orbit). These are the third and fourth planets found within the TAPAS project, a HARPS-N monitoring of evolved planetary systems identified with the Hobby-Eberly Telescope.Comment: 9 pages, 6 figures. Accepted by Astronomy and Astrophysic