Rotational Modulation of M/L Dwarfs Due to Magnetic Spots

Abstract

We find periodic I-band variability in two ultracool dwarfs, TVLM 513-46546 and 2MASS J00361617+1821104, on either side of the M/L dwarf boundary. Both of these targets are short-period radio transients, with the detected I-band periods matching those found at radio wavelengths. We attribute the detected I-band periodicities to the periods of rotation of the dwarfs, supported by radius estimates and measured values for the objects. Based on the detected period of rotation in the I band, along with confirmation of strong magnetic fields from recent radio observations, we argue for magnetically induced spots as the cause of this periodic variability. The I-band rotational modulation of the L3.5 dwarf 2MASS J00361617+1821104 appeared to vary in amplitude with time. We conclude that the most likely cause of the I-band variability for this object is magnetic spots, possibly coupled with time-evolving features such as dust clouds.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Oct 20, 2007
Accession Number
ADA477306

Entities

People

  • A. Antonova
  • A. Golden
  • F. J. Vrba
  • G. Hallinan
  • H. Clifford Lane
  • J. G. Doyle
  • R. F. Butler
  • R. P. Boyle
  • Robert T. Zavala
  • S. Bourke

Organizations

  • United States Naval Observatory Flagstaff Station

Tags

Communities of Interest

  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Acquisition
  • Amplitude
  • Data Acquisition
  • Data Sets
  • Magnetic Fields
  • Measurement
  • Modulation
  • Observation
  • Observatories
  • Periodic Variations
  • Photometry
  • Spectra
  • Standards
  • Surveys
  • Temperature Gradients
  • United States
  • Universities

Fields of Study

  • Physics

Readers

  • Astronomy/Astrophysics