PENELLOPE

II. CVSO 104: A pre-main sequence close binary with an optical companion in Ori OB1^★

¹ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
e-mail: afrasca@oact.inaf.it
² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany
³ INAF – Osservatorio Astronomico di Capodimonte, via Moiariello, 16, 80131 Napoli, Italy
⁴ Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network (ELKH), Konkoly-Thege Miklós út 15-17, 1121 Budapest, Hungary
⁵ ELTE Eötvös Loránd University, Institute of Physics, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
⁶ Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, PR China
⁷ INAF – Osservatorio Astronomico di Roma, via di Frascati 33, 00078 Monte Porzio Catone, Italy
⁸ Kavli Institute for Astronomy and Astrophysics, Peking University, Yiheyuan 5, Haidian Qu, 100871 Beijing, PR China
⁹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
¹⁰ SETI Institute, 189 Bernardo Ave, Suite 200, Mountain View, CA 94043, USA
¹¹ Stony Brook University, Stony Brook, NY 11794, USA
¹² Crimean Astrophysical Observatory, 298409 Nauchny, Crimea
¹³ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁴ Observatoire de Paris, PSL University, Sorbonne Université, CNRS, LERMA, 75014 Paris, France

Received: 30 June 2021
Accepted: 11 September 2021

Abstract

We present the results of our study of the close pre-main sequence spectroscopic binary CVSO 104 in Ori OB1, based on data obtained within the PENELLOPE legacy program. We derive, for the first time, the orbital elements of the system and the stellar parameters of the two components. The system is composed of two early M-type stars and has an orbital period of about five days and a mass ratio of 0.92, but contrary to expectations, it does not appear to have a tertiary companion. Both components have been (quasi-)synchronized, but the orbit is still very eccentric. The spectral energy distribution clearly displays a significant infrared excess that is compatible with a circumbinary disk. The analysis of He I and Balmer line profiles, after the removal of the composite photospheric spectrum, reveals that both components are accreting at a similar level. We also observe excess emission in Hα and Hβ, which appears redshifted or blueshifted by more than 100 km s⁻¹ with respect to the mass center of the system, depending on the orbital phase. This additional emission could be connected with accretion structures, such as funnels of matter from the circumbinary disk. We also analyze the optical companion located at about 2.″4 from the spectroscopic binary. This companion, which we named CVSO 104 B, turns out to be a background Sun-like star that is not physically associated with the PMS system and does not belong to Ori OB1.