Properties of Galactic B[e] Supergiants: V. 3 Pup -- constraining the orbital parameters and modeling the circumstellar environments

Abstract

We report the results of a long-term spectroscopic monitoring of the A-type supergiant with the B[e] phenomenon 3 Pup = HD 62623. We confirm earlier findings that it is a binary system. The orbital parameters were derived using cross-correlation of the spectra in a range of 4460-4632 A, which contains over 30 absorption lines. The orbit was found circular with a period of $137.4\pm 0.1$ days, radial velocity semi-amplitude $K_1=5.0\pm 0.8$ km s${}^{-1}$, systemic radial velocity $\gamma =+26.4\pm 2.0$ km s${}^{-1}$, and the mass function $f(m)=(1.81_{-0.76}^{+0.97})\times 10^{-3}$ M${}_{\odot }$. The object may have evolved from a pair with initial masses of $\sim$6.0 M${}_{\odot }$ and $\sim$3.6 M${}_{\odot }$ with an initial orbital period of $\sim$5 days. Based on the fundamental parameters of the A-supergiant (luminosity $\log$ L/L${}_{\odot }=4.1\pm$0.1 and effective temperature T${}_{\mathrm{eff}}=8500\pm$500 K) and evolutionary tracks of mass-transferring binaries, we found current masses of the gainer M${}_2=8.8\pm$0.5 M${}_{\odot }$ and donor M${}_1=0.75\pm 0.25$ M${}_{\odot }$. We also modeled the object's IR-excess and derived a dust mass of $\sim 5\times 10^{-5}$ M${}_{\odot }$ in the optically-thin dusty disk. The orbital parameters and properties of the H$\alpha$ line profile suggest that the circumstellar gaseous disk is predominantly circumbinary. The relatively low mass of the gainer led us to a suggestion that 3 Pup should be excluded from the B[e] supergiant group and moved to the FS CMa group. Overall these results further support our original suggestion that FS CMa objects are binary systems, where an earlier mass-transfer caused formation of the circumstellar envelope.

13 pages, 9 figures, 4 tables, accepted in The Astrophysical Journal

References in corpus (4)

• Spin-up and hot spots can drive mass out of a binary
• Discovery of SiO band emission from Galactic B[e] supergiants
• Probing Dust Settling in Proto-planetary Disks with ALMA
• Spectral atlas of A-type supergiants

Cited by in corpus (1)

• First detection of a magnetic field in low-luminosity B[e] stars: New scenarios for the nature and evolutionary stages of FS CMa stars