Jet from the enigmatic high-latitude star BP Psc and evolutionary status of its driving source

Abstract

ABSTRACT BP Psc is an active late-type (sp:G9) star with unclear evolutionary status lying at high-galactic latitude b = −57°. It is also the source of the well collimated bipolar jet. We present results of the proper motion and radial velocity study of BP Psc outflow based on the archival Hα imaging with the GMOS camera at 8.1-m Gemini-North telescope as well as recent imaging and long-slit spectroscopy with the SCORPIO multimode focal reducer at 6-m BTA telescope of SAO RAS. The 3D kinematics of the jet revealed the full spatial velocity up to ∼140 km s−1 and allows us to estimate the distance to BP Psc system as D = 135 ± 40 pc. This distance leads to an estimation of the central source luminosity L* ≈ 1.2 L⊙, indicating that it is the ≈1.3M⊙ T Tauri star with an age t ≲ 7 Myrs. We measured the electron density of order Ne ∼ 102 cm−3 and mean ionization fraction f ≈ 0.04 within the jet knots and estimated upper limit of the mass-loss rate in NE lobe as $\dot{M}_{\rm out}\approx 1.2\cdot 10^{-8}{\rm M}_{\odot }\,{\rm yr}^{-1}$. The physical characteristics of the outflow are typical for the low-excitation YSO jets and consistent with the magnetocentrifugal mechanism of its launching and collimation. Prominent wiggling pattern revealed in Hα images allowed us to suppose the existence of a secondary substellar companion in a non-coplanar orbit and estimate its most plausible mass as Mp ≈ 30MJup. We conclude that BP Psc is one of the closest to the Sun young jet-driving systems and its origin is possibly related to the episode of star formation triggered by expanding supershells in second Galactic quadrant.