928 research outputs found
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 , log ,
[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
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 K0 giant with a = minimum mass companion in
AU (d),
orbit. HD 95127, a log/=,
, K0 giant has a = minimum mass companion in
AU (d), orbit.
Finally, HD 216536, is a K0 giant with a minimum mass companion in
AU (d),
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
Ecospheres around binary stars
Scientific investigations concerning ecospheres of other stars are very important for understanding the posibilities of existence and evolution of extraterrestrial life. In several last years astronomers discovered hundreds of extrasolar planets. Identification of stars with ecospheres is the first step in selecting those planets which could be inhabited. Usually an ecosphere of a single star is considered but it may also exist in planetary systems with two suns. This possibility is very promising in search for life on other planets as more that 60 % of stars reside in binary or multiple systems
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 (, 0.4)
companion with an orbital period of 26.468 days in a circular () orbit
around a giant evolved (, ) star
with . This is the most massive and oldest star
found to be hosting a close-in giant planet. Its proximity to its host
() means that the planet has a 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 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 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
Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. V.: A Massive Jupiter orbiting the very low metallicity giant star BD+03 2562 and a possible planet around HD~103485
We present two evolved stars from the TAPAS (Tracking Advanced PlAnetary
Systems) with HARPS-N project devoted to RV precision measurements of
identified candidates within the PennState - Torun Centre for Astronomy Planet
Search. Evolved stars with planets are crucial to understand the dependency of
the planet formation mechanism on the mass and metallicity of the parent star
and to study star-planet interactions. The paper is based on precise radial
velocity (RV) measurements, for HD 103485 we collected 57 epochs over 3317 days
with the Hobby-Eberly Telescope and its High Resolution Spectrograph and 18
ultra-precise HARPS-N data over 919 days. For BD+03 2562 we collected 46 epochs
of HET data over 3380 days and 19 epochs of HARPS-N data over 919 days. We
present the analysis of the data and the search for correlations between the RV
signal and stellar activity, stellar rotation and photometric variability.
Based on the available data, we interpret the RV variations measured in both
stars as Keplerian motion. Both stars have masses close to Solar (1.11 and
1.14), very low metallicities ([Fe/H]=-0.50 and -0.71), and, both have Jupiter
planetary mass companions (m sin i=7 and 6.4 Mj), in close to terrestrial
orbits (1.4 and 1.3~au), with moderate eccentricities (e=0.34 and 0.2).
However, we cannot totally exclude that the signal in the case of HD~103485 is
due to rotational modulation of active regions. Based on the current data, we
conclude that BD+03 2562 has a bona fide planetary companion while for HD
103485 we cannot totally exclude that the best explanation for the RV signal
modulations is not the existence of a planet but stellar activity. If, the
interpretation remains that both stars have planetary companions they represent
systems orbiting very evolved stars with very low metallicities, a challenge to
the conditions required for the formation of massive giant gas planets.Comment: Acepted A&A 12 pages, 11 figure
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&
Perancangan Expert System Untuk Troubleshooting Mesin Dengan Decision Table(studi Kasus Di PT. Adi Putro Wirasejati)
PT. Adi Putro Wirasejati merupakan salah satu karoseri yang bergerak dalam bidang pembentukan body kendaraan bus dan minibus. Perusahaan memiliki kendala yaitu terhambatnya proses produksi karena beberapa kali mesin produksi tidak dapat berfungsi dan harus dilakukan kegiatan perawatan. Departemen maintenance yang memiliki 11 karyawan menangani semua mesin dalam lini produksi yang berjumlah cukup besar. Hal ini menyebabkan terjadinya beberapa kesalahan diagnosa kerusakan yang menimbulkan kesalahan dalam pengambilan keputusan, sehingga menyebabkan adanya perhentian lini produksi akibat dari bottleneck mesin yang rusak. Dalam perawatan mesin, diperlukan tenaga ahli di bidang mesin yang harus siap sedia bila terjadi masalah atau kerusakan. Akan tetapi, pakar atau orang ahli di bidang mesin tidak selalu siap sedia 24 jam sehari. Oleh karena itu dibutuhkan prototype yang dapat menyimpan pengetahuan pakar dan melakukan konsultasi perbaikan mesin. Penelitian ini menggunakan metode Expert System sebagai penalaran untuk mencari rekomendasi perbaikan, dan Decision Table sebagai tools untuk menyimpan pengetahuan kerusakan mesin yang digunakan oleh expert system dalam mencari rekomendasi perbaikan. Tahap pertama yang dilakukan adalah melihat sistem troubleshooting yang bekerja pada departemen maintenance. Dilanjutkan identifikasi permasalahan lambatnya penanganan kerusakan mesin, selanjutnya merancang desain sistem baru yaitu expert system untuk membantu mencari rekomendasi perbaikan kerusakan mesin. Setelah merancang sistem maka dibuat program expert system sesuai yang dirancang.Setelah pembuatan program maka dapat disimpulkan konsultasi pada sistem expert system, kerusakan mesin mampu mempercepat performansi kinerja departemen maintenance dalam melaksanakan perbaikan kerusakan mesin. Bila sistem lama dalam mencari rekomendasi kerusakan mesin membutuhkan waktu antara 15-45 menit bahkan lebih, pada sistem baru akan memberikan rekomendasi dalam waktu kurang lebih 5 menit dengan rekomendasi kerusakan yang tepat sehingga tidak terjadi salah pendugaan. Pengetahuan pakar sudah tersimpan dalam sistem sehingga mempermudah kapan saja berkonsultasi, sistem dapat beroperasi selama 7 hari dalam seminggu dan 365 hari dalam setahun. Selain itu, prototype expert system kerusakan mesin mampu memberikan informasi basis pengetahuan tentang kerusakan mesin juga dapat digunakan sebagai pelatihan untuk menangani kerusakan mesin
Yield improvement through female homosexual hybrids and sex genetics of sweet gourd (Momordica cochinchinensis Spreng.)
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