Bibcode
Villaver, E.; Niedzielski, A.; Wolszczan, A.; Nowak, G.; Kowalik, K.; Adamów, M.; Maciejewski, G.; Deka-Szymankiewicz, B.; Maldonado, J.
Bibliographical reference
Astronomy and Astrophysics, Volume 606, id.A38, 11 pp.
Advertised on:
10
2017
Journal
Citations
6
Refereed citations
5
Description
Context. Evolved stars with planets are crucial to understanding the
dependency of the planet formation mechanism on the mass and metallicity
of the parent star and to studying star-planet interactions.
Aims: We present two evolved stars (HD 103485 and BD+03 2562) from the
Tracking Advanced PlAnetary Systems (TAPAS) with HARPS-N project devoted
to RV precision measurements of identified candidates within the
PennState - Toruń Centre for Astronomy Planet Search.
Methods: 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 (HET) 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. Results: 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
M⊙ HD 103485 and 1.14 M⊙ BD+03 2562), very
low metallicities ([Fe/H] = - 0.50 and - 0.71 for HD 103485 and BD+03
2562), and both have Jupiter planetary mass companions
(m2sini = 7 and 6.4 MJ for HD 103485 and BD+03
2562 resp.) in close to terrestrial orbits (1.4 au HD 103485 and 1.3 au
BD+03 2562) with moderate eccentricities (e = 0.34 and 0.2 for HD 103485
and BD+03 2562). However, we cannot totally rule-out the possibility
that the signal in the case of HD 103485 is due to rotational modulation
of active regions. Conclusions: 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 the possibility 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.
Based on observations obtained with the Hobby-Eberly Telescope, which is
a joint project of the University of Texas at Austin, the Pennsylvania
State University, Stanford University,
Ludwig-Maximilians-Universität München, and
Georg-August-Universität Göttingen.Based on observations made
with the Italian Telescopio Nazionale Galileo (TNG) operated on the
island of La Palma by the Fundación Galileo Galilei of the INAF
(Istituto Nazionale di Astrofisica) at the Spanish Observatorio del
Roque de los Muchachos of the Instituto de Astrofísica de
Canarias.
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