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

Abstract

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.

Authors:
;  [1]
  1. Dept. Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)
Publication Date:
OSTI Identifier:
22663398
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 843; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; 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

Citation Formats

MacDonald, James, and Mullan, D. J.. LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7A07.
MacDonald, James, & Mullan, D. J.. LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism. United States. doi:10.3847/1538-4357/AA7A07.
MacDonald, James, and Mullan, D. J.. Mon . "LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism". United States. doi:10.3847/1538-4357/AA7A07.
@article{osti_22663398,
title = {LSPM J1314+1320: An Oversized Magnetic Star with Constraints on the Radio Emission Mechanism},
author = {MacDonald, James and Mullan, D. J.},
abstractNote = {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.},
doi = {10.3847/1538-4357/AA7A07},
journal = {Astrophysical Journal},
number = 2,
volume = 843,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2017},
month = {Mon Jul 10 00:00:00 EDT 2017}
}