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Verfasst von:Stock, Katja [VerfasserIn]   i
 Reffert, Sabine [VerfasserIn]   i
 Stock, Stephan [VerfasserIn]   i
 Trifonov, Trifon [VerfasserIn]   i
 Quirrenbach, Andreas [VerfasserIn]   i
Titel:Precise radial velocities of giant stars - XII. Evidence against the proposed planet Aldebaran b
Verf.angabe:Katja Reichert, Sabine Reffert, Stephan Stock, Trifon Trifonov, and Andreas Quirrenbach
E-Jahr:2019
Jahr:01 May 2019
Umfang:15 S.
Fussnoten:Gesehen am 17.12.2019
Titel Quelle:Enthalten in: Astronomy and astrophysics
Ort Quelle:Les Ulis : EDP Sciences, 1969
Jahr Quelle:2019
Band/Heft Quelle:625(2019) Artikel-Nummer A22, 15 Seiten
ISSN Quelle:1432-0746
Abstract:Radial-velocity variations of the K giant star Aldebaran (<i>α<i/> Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses.<i>Aims.<i/> We want to further investigate the hypothesis of an extrasolar planet around Aldebaran.<i>Methods.<i/> We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed.<i>Results.<i/> As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (<i>P<i/> = 607 d) and a larger eccentricity (<i>e<i/> = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms<sup>−1<sup/>. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues.<i>Conclusions.<i/> The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.
DOI:doi:10.1051/0004-6361/201834028
URL:Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.

Volltext ; Verlag: https://doi.org/10.1051/0004-6361/201834028
 Volltext: https://www.aanda.org/articles/aa/abs/2019/05/aa34028-18/aa34028-18.html
 DOI: https://doi.org/10.1051/0004-6361/201834028
Datenträger:Online-Ressource
Sprache:eng
K10plus-PPN:1685743420
Verknüpfungen:→ Zeitschrift

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