LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism

Journal Article · Mon Jul 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7A07· OSTI ID:22663398

MacDonald, James; Mullan, D. J. ^[1]

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1. Dept. Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

LSPM J1314+1320 (=NLTT 33370) is a binary star system consisting of two nearly identical pre-main-sequence stars of spectral type M7. The system is remarkable among ultracool dwarfs for being the most luminous radio emitter over the widest frequency range. Masses and luminosities are at first sight consistent with the system being coeval at age ∼80 Myr according to standard (nonmagnetic) evolutionary models. However, these models predict an average effective temperature of ∼2950 K, which is 180 K hotter than the empirical value. Thus, the empirical radii are oversized relative to the standard models by ≈13%. We demonstrate that magnetic stellar models can quantitatively account for the oversizing. As a check on our models, we note that the radio emission limits the surface magnetic field strengths: the limits depend on identifying the radio emission mechanism. We find that the field strengths required by our magnetic models are too strong to be consistent with gyrosynchrotron emission but are consistent with electron cyclotron maser emission.

• OSTI ID: 22663398
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 843; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
COSMIC RADIO SOURCES
DWARF STARS
ELECTRONS
EMISSION
LIMITING VALUES
LUMINOSITY
MAGNETIC FIELDS
MAGNETIC STARS
MAIN SEQUENCE STARS
MASS
MICROWAVE AMPLIFIERS
STANDARD MODEL
SURFACES