A Search for Exoplanets around Northern Circumpolar Stars. VII. Detection of Planetary Companion Orbiting the Largest Host Star HD 18438

Byeong Cheol Lee, Jae Rim Koo, Gwanghui Jeong, Myeong Gu Park, Inwoo Han, Yeon Ho Choi

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

We have been conducting a exoplanet search survey using Bohyunsan Observatory Echelle Spectrograph (BOES) for the last 18 years. We present the detection of exoplanet candidate in orbit around HD 18438 from high-precision radial velocity (RV) mesurements. The target was already reported in 2018 (Bang et al. 2018). They conclude that the RV variations with a period of 719 days are likely to be caused by the pulsations because the Lomb-Scargle periodogram of HIPPARCOS photometric and Hα EW variations for HD 18438 show peaks with periods close to that of RV variations and there were no correlations between bisectors and RV measurements. However, the data were not sufficient to reach a firm conclusion. We obtained more RV data for four years. The longer time baseline yields a more accurate determination with a revised period of 803 ± 5 days and the planetary origin of RV variations with a minimum planetary companion mass of 21 ± 1 MJup. Our current estimate of the stellar parameters for HD 18438 makes it currently the largest star with a planetary companion.

Original languageEnglish
Pages (from-to)35-40
Number of pages6
JournalJournal of the Korean Astronomical Society
Volume56
Issue number1
DOIs
StatePublished - 2023

Keywords

  • star: individual: HD 18438
  • techniques: radial velocities

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