Evidence for an FU orionis-like outburst from a classical T tauri star

Adam A. Miller, Lynne A. Hillenbrand, Kevin R. Covey, Dovi Poznanski, Jeffrey M. Silverman, Io K.W. Kleiser, Brbara Rojas-Ayala, Philip S. Muirhead, S. Bradley Cenko, Joshua S. Bloom, Mansi M. Kasliwal, Alexei V. Filippenko, Nicholas M. Law, Eran O. Ofek, Richard G. Dekany, Gustavo Rahmer, David Hale, Roger Smith, Robert M. Quimby, Peter NugentJanet Jacobsen, Jeff Zolkower, Viswa Velur, Richard Walters, John Henning, Khanh Bui, Dan McKenna, Shrinivas R. Kulkarni, Christopher R. Klein, Michael Kandrashoff, Alekzandir Morton

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

We present pre- and post-outburst observations of the new FU Orionis-like young stellar object PTF 10qpf (also known as LkHα 188-G4 and HBC 722). Prior to this outburst, LkHα 188-G4 was classified as a classical TTauri star (CTTS) on the basis of its optical emission-line spectrum superposed on a K8-type photosphere and its photometric variability. The mid-infrared spectral index of LkHα 188-G4 indicates a Class II-type object. LkHα 188-G4 exhibited a steady rise by 1mag over 11 months starting in August 2009, before a subsequent more abrupt rise of >3mag on a timescale of 2 months. Observations taken during the eruption exhibit the defining characteristics of FU Orionis variables: (1) an increase in brightness by ≳4mag, (2) a bright optical/near-infrared reflection nebula appeared, (3) optical spectra are consistent with a G supergiant and dominated by absorption lines, the only exception being Hα which is characterized by a P Cygni profile, (4) near-infrared spectra resemble those of late K-M giants/supergiants with enhanced absorption seen in the molecular bands of CO and H2O, and (5) outflow signatures in H and He are seen in the form of blueshifted absorption profiles. LkHα 188-G4 is the first member of the FU Orionis-like class with a well-sampled optical to mid-infrared spectral energy distribution in the pre-outburst phase. The association of the PTF 10qpf outburst with the previously identified CTTS LkHα 188-G4 (HBC 722) provides strong evidence that FU Orionis-like eruptions represent periods of enhanced disk accretion and outflow, likely triggered by instabilities in the disk. The early identification of PTF 10qpf as an FU Orionis-like variable will enable detailed photometric and spectroscopic observations during its post-outburst evolution for comparison with other known outbursting objects.

Original languageEnglish
Article number80
JournalAstrophysical Journal
Volume730
Issue number2
DOIs
Publication statusPublished - 1 Apr 2011

Keywords

  • stars: formation
  • stars: individual (LkHa 188-G4, HBC 722)
  • stars: pre-main sequence
  • stars: variables: T Tauri, Herbig Ae/Be
  • stars: winds, outflows

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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