Magnetic nonthermal activity in the T tauri system

Robert B. Phillips, Colin J. Lonsdale, Eric Feigelson

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The pre-main-sequence binary T Tauri was observed in 1991 September using a simultaneous combination of the Very Large Array (VLA) and a four-antenna Very Long Baseline Interferometry (VLBI) array operating at λ = 18 cm. Strong circular polarization (25%-30%) was detected in the VLA measurements, and there was evidence for variations in both circular polarization V and total intensity / on time scales of 1 hr. VLBI measurements of T Tauri taken in parallel failed to detect any compact flux density, despite having sufficient sensitivity to measure fringe visibilities as faint as 15% of the total flux density from the source. If the radiation from T Tau resembles that from other stellar radio sources in circular polarization fraction n, the VLBI measurements imply a lower limit on the size of unpolarized radiation of ∼ 1 AU or 70 stellar radii. The circular polarization and rapid flux variations indicate a significant nonthermal contribution in the radio emission from T Tau, previously thought to be solely thermal free-free radiation from stellar winds or inflows. Reanalysis of high-resolution 1983 VLA data implicates the protostar T Tau(S) as the probable source of the circular polarization. It thus appears to be the first protostar system to show nonthermal radio activity, previously documented to be present around weak-lined T Tauri stars (e.g., Phillips, Lonsdale, & Feigelson 1991).

Original languageEnglish (US)
JournalAstrophysical Journal
Volume403
Issue number1 PART II
DOIs
StatePublished - Jan 1 1993

Fingerprint

circular polarization
polarization
Very Large Array (VLA)
very long baseline interferometry
interferometry
protostars
radiation
flux density
radio
T Tauri stars
stellar winds
radio emission
radioactivity
visibility
antenna
inflow
antennas
timescale
radii
sensitivity

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Phillips, Robert B. ; Lonsdale, Colin J. ; Feigelson, Eric. / Magnetic nonthermal activity in the T tauri system. In: Astrophysical Journal. 1993 ; Vol. 403, No. 1 PART II.
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Magnetic nonthermal activity in the T tauri system. / Phillips, Robert B.; Lonsdale, Colin J.; Feigelson, Eric.

In: Astrophysical Journal, Vol. 403, No. 1 PART II, 01.01.1993.

Research output: Contribution to journalArticle

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