No Planet around the K Giant Star 42 Draconis
Artie P. Hatzes, Volker Perdelwitz, Marie Karjalainen, Jana K\"ohler,, Michael Hartmann

TL;DR
Extended radial velocity monitoring of 42 Draconis shows no evidence of a planet, instead revealing stellar oscillations that mimic planetary signals, highlighting the importance of long-term, high-quality data in exoplanet detection around giant stars.
Contribution
This study demonstrates that long-term RV variations previously attributed to a planet are actually caused by stellar oscillations, emphasizing the need for comprehensive data analysis.
Findings
No planet around 42 Dra confirmed by photometry.
Long-term RV variations are due to stellar oscillations.
Stellar oscillations can mimic planetary signals in giant stars.
Abstract
Published radial velocity (RV) measurements of the K giant star 42 Dra reveal variations consistent with a 3.9 M_Jup mass companion in a 479-d orbit. This exoplanet can be confirmed if these variations are long-lived and coherent. Continued monitoring may also reveal other companions. We have acquired additional RV measurements of 42 Dra spanning fifteen years. Periodogram analyses were used to investigate the stability of the planet RV signal. We also investigated variations in the spectral line shapes using the bisector velocity span as well as infrared photometry from the COBE mission. The new RV measurements do not follow the published planet orbit. An orbital solution using the 2004 - 2011 data yields a period and eccentricity consistent with the published values, but the RV amplitude has decreased by a factor of four from the earlier measurements. Including some additional RV…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astronomy and Astrophysical Research · Scientific Research and Discoveries
