HD 1397b: A Transiting Warm Giant Planet Orbiting A v = 7.8 mag Subgiant Star Discovered by TESS

Rafael Brahm, Néstor Espinoza, Andrés Jordán, Thomas Henning, Paula Sarkis, Matias I. Jones, Matias R. Diaz, James S. Jenkins, Leonardo Vanzi, Abner Zapata, Cristobal Petrovich, Diana Kossakowski, Markus Rabus, Felipe Rojas, Pascal Torres

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


We report the discovery of a transiting planet first identified as a candidate in Sector 1 of the Transiting Exoplanet Survey Satellite (TESS), and then confirmed with precision radial velocities. HD 1397b has a mass of , a radius of , and orbits its bright host star (V = 7.8 mag) with an orbital period of d on a moderately eccentric orbit (). With a mass of , a radius of , and an age of Gyr, the solar-metallicity host star has already departed from the main sequence. We find evidence in the radial velocity measurements of a secondary signal with a longer period. We attribute it to the rotational modulation of stellar activity, but a long-term radial velocity monitoring would be necessary to discard if this signal is produced by a second planet in the system. The HD 1397 system is among the brightest ones currently known to host a transiting planet, which will make it possible to perform detailed follow-up observations in order to characterize the properties of giant planets orbiting evolved stars.

Original languageEnglish
Article number45
JournalAstronomical Journal
Issue number1
StatePublished - 2019
Externally publishedYes


  • planetary systems
  • planets and satellites: detection
  • planets and satellites: gaseous planets


Dive into the research topics of 'HD 1397b: A Transiting Warm Giant Planet Orbiting A v = 7.8 mag Subgiant Star Discovered by TESS'. Together they form a unique fingerprint.

Cite this