A Search for Exoplanets around Northern Circumpolar Stars. XI. A Planetary Companion around HD 112987 and a Planetary Companion Candidate around HD 58545
7 affiliations
- 1Korea Astronomy and Space Science Institute
- 2Korea University of Science and Technology
- 3Chinese Academy of Sciences
- 4University of Chinese Academy of Sciences
- 5Kongju National University
- 6Kyungpook National University
- 7Pocheon Art Valley Astronomical Science Museum
Abstract
We present precise radial velocity (RV) measurements of the northern circumpolar giant stars HD 58545 and HD 112987 obtained over 8 yr with the Bohyunsan Observatory Echelle Spectrograph and supplemented during the final 3 yr by the Network of Robotic Echelle Spectrographs. RV variations in giant stars may arise from orbiting companions or intrinsic phenomena, including pulsations, chromospheric activity, and rotational modulation. To distinguish these possibilities, we analyzed line-profile variations, line bisectors, chromospheric activity indicators, and photometric data, and modeled the RV time series with Keplerian orbits using Markov Chain Monte Carlo sampling. For HD 58545, the best-fitting Keplerian model yields an orbital period of 450.44 − 4.63 + 3.35 days and a minimum companion mass of 3.65 − 0.58 + 0.61 M J . For HD 112987, we derive an orbital period of 554.96 − 4.67 + 4.14 days and a minimum companion mass of 8.48 − 0.73 + 0.96 M J . None of the activity diagnostics for HD 112987 exhibits significant variability at the RV period, consistent with a Keplerian interpretation. In contrast, several activity diagnostics of HD 58545 exhibit periodicities comparable to the RV period, which is also consistent within the uncertainties with the projected rotational timescale, P rot / sin i = 462 ± 33 days . Thus, rotationally modulated stellar variability may contribute to the RV signal. Although the signal can be described by a Keplerian model, the current data cannot distinguish unambiguously between a planetary companion and intrinsic stellar variability. We therefore conclude that HD 112987 hosts a planetary companion, whereas further monitoring is required to determine the origin of the RV signal in HD 58545.
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BibTeX
@article{lee2026search,
title = {{A Search for Exoplanets around Northern Circumpolar Stars. XI. A Planetary Companion around HD 112987 and a Planetary Companion Candidate around HD 58545}},
author = {Byeong-Cheol Lee and Shenghong Gu and Beomdu Lim and Yeon-Ho Choi and Jae-Rim Koo and Hyeong-Ill Oh and Tae-Yang Bang and Sang-Hee Kim and Myeong-Gu Park},
journal = {The Astronomical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-3881/aeb262},
url = {https://iopscience.iop.org/article/10.3847/1538-3881/aeb262},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Search for Exoplanets around Northern Circumpolar Stars. XI. A Planetary Companion around HD 112987 and a Planetary Companion Candidate around HD 58545
AU - Byeong-Cheol Lee
AU - Shenghong Gu
AU - Beomdu Lim
AU - Yeon-Ho Choi
AU - Jae-Rim Koo
AU - Hyeong-Ill Oh
AU - Tae-Yang Bang
AU - Sang-Hee Kim
AU - Myeong-Gu Park
PY - 2026
DA - 2026/11/05
JO - The Astronomical Journal
DO - 10.3847/1538-3881/aeb262
UR - https://iopscience.iop.org/article/10.3847/1538-3881/aeb262
AB - We present precise radial velocity (RV) measurements of the northern circumpolar giant stars HD 58545 and HD 112987 obtained over 8 yr with the Bohyunsan Observatory Echelle Spectrograph and supplemented during the final 3 yr by the Network of Robotic Echelle Spectrographs. RV variations in giant stars may arise from orbiting companions or intrinsic phenomena, including pulsations, chromospheric activity, and rotational modulation. To distinguish these possibilities, we analyzed line-profile variations, line bisectors, chromospheric activity indicators, and photometric data, and modeled the RV time series with Keplerian orbits using Markov Chain Monte Carlo sampling. For HD 58545, the best-fitting Keplerian model yields an orbital period of 450.44 − 4.63 + 3.35 days and a minimum companion mass of 3.65 − 0.58 + 0.61 M J . For HD 112987, we derive an orbital period of 554.96 − 4.67 + 4.14 days and a minimum companion mass of 8.48 − 0.73 + 0.96 M J . None of the activity diagnostics for HD 112987 exhibits significant variability at the RV period, consistent with a Keplerian interpretation. In contrast, several activity diagnostics of HD 58545 exhibit periodicities comparable to the RV period, which is also consistent within the uncertainties with the projected rotational timescale, P rot / sin i = 462 ± 33 days . Thus, rotationally modulated stellar variability may contribute to the RV signal. Although the signal can be described by a Keplerian model, the current data cannot distinguish unambiguously between a planetary companion and intrinsic stellar variability. We therefore conclude that HD 112987 hosts a planetary companion, whereas further monitoring is required to determine the origin of the RV signal in HD 58545.
SN - 0004-6256
SN - 1538-3881
ER -