Episodic mass loss in binary evolution to the Wolf-Rayet phase: Keck and HST proper motions of RY Scuti's nebula

Nathan Smith, Robert D. Gehrz, Randy Campbell, Marc Kassis, David Le Mignant, Kawailehua Kuluhiwa, Alexei V. Filippenko

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Binary mass transfer via -Roche lobe overflow (RLOF) is a key channel for producing stripped-envelope Wolf-Rayet (WR) stars and may be critical to account for Type Ib/c supernova progenitors. RY Scuti is an extremely rare example of a massive binary star caught in this brief but important phase. Its unusual toroidal nebula indicates equatorial mass loss during RLOF, while the mass-gaining star is apparently embedded in an opaque accretion disc. RY Scuti's toroidal nebula has two components: an inner ionized double-ring system, and an outer dust torus that is roughly twice the size of the ionized rings. We present two epochs of L-band Keck natural guide star adaptive optics (NGS-AO) images of the dust torus, plus three epochs of Hubble Space Telescope (HST) images of the ionized gas rings. Proper motions show that the inner ionized rings and the outer dust torus, while having similar geometry, came from two separate ejection events roughly 130 and 250 yr ago. This suggests that WR star formation via RLOF in massive contact binaries can be accompanied by eruptive and episodic bursts of mass loss, reminiscent of luminous blue variables (LBVs). We speculate that the repeating outbursts may arise in the mass gainer from instabilities associated with a high accretion rate. In the case of RY Scuti, we know of no historical evidence that either of its mass-loss events were observed as luminous outbursts, but if discrete mass-loss episodes in other RLOF binaries are accompanied by luminous outbursts, they might contribute to the population of extragalactic optical transients. When RLOF ends for RY Scuti, the overluminous mass gainer, currently surrounded by an accretion disc, will probably become a B[e] supergiant and may outshine the hotter stripped-envelope mass-donor star that should die as a Type Ib/c supernova.

Original languageEnglish (US)
Pages (from-to)1959-1972
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume418
Issue number3
DOIs
StatePublished - Dec 2011

Fingerprint

wolves
proper motion
nebulae
Hubble Space Telescope
lobes
outburst
Wolf-Rayet stars
dust
rings
accretion
stars
accretion disks
supernovae
envelopes
time measurement
loss
binary stars
ionized gases
ultrahigh frequencies
massive stars

Keywords

  • Binaries: eclipsing
  • Binaries: general
  • Circumstellar matter
  • Stars: evolution
  • Stars: mass-loss
  • Supernovae: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Episodic mass loss in binary evolution to the Wolf-Rayet phase : Keck and HST proper motions of RY Scuti's nebula. / Smith, Nathan; Gehrz, Robert D.; Campbell, Randy; Kassis, Marc; Le Mignant, David; Kuluhiwa, Kawailehua; Filippenko, Alexei V.

In: Monthly Notices of the Royal Astronomical Society, Vol. 418, No. 3, 12.2011, p. 1959-1972.

Research output: Contribution to journalArticle

Smith, Nathan ; Gehrz, Robert D. ; Campbell, Randy ; Kassis, Marc ; Le Mignant, David ; Kuluhiwa, Kawailehua ; Filippenko, Alexei V. / Episodic mass loss in binary evolution to the Wolf-Rayet phase : Keck and HST proper motions of RY Scuti's nebula. In: Monthly Notices of the Royal Astronomical Society. 2011 ; Vol. 418, No. 3. pp. 1959-1972.
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