Periodic optical variability of radio-detected ultracool dwarfs

L. K. Harding, G. Hallinan, R. P. Boyle, A. Golden, Navtej Singh, B. Sheehan, R. T. Zavala, R. F. Butler

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A fraction of very low mass stars and brown dwarfs are known to be radio active, in some cases producing periodic pulses. Extensive studies of two such objects have also revealed optical periodic variability, and the nature of this variability remains unclear. Here, we report on multi-epoch optical photometric monitoring of six radio-detected dwarfs, spanning the ∼M8-L3.5 spectral range, conducted to investigate the ubiquity of periodic optical variability in radio-detected ultracool dwarfs. This survey is the most sensitive ground-based study carried out to date in search of periodic optical variability from late-type dwarfs, where we obtained 250 hr of monitoring, delivering photometric precision as low as ∼0.15%. Five of the six targets exhibit clear periodicity, in all cases likely associated with the rotation period of the dwarf, with a marginal detection found for the sixth. Our data points to a likely association between radio and optical periodic variability in late-M/early-L dwarfs, although the underlying physical cause of this correlation remains unclear. In one case, we have multiple epochs of monitoring of the archetype of pulsing radio dwarfs, the M9 TVLM 513-46546, spanning a period of 5 yr, which is sufficiently stable in phase to allow us to establish a period of 1.95958 ± 0.00005 hr. This phase stability may be associated with a large-scale stable magnetic field, further strengthening the correlation between radio activity and periodic optical variability. Finally, we find a tentative spin-orbit alignment of one component of the very low mass binary, LP 349-25.

Original languageEnglish (US)
Article number101
JournalAstrophysical Journal
Volume779
Issue number2
DOIs
StatePublished - Dec 20 2013

Fingerprint

radio
monitoring
time measurement
radioactivity
periodicity
periodic variations
magnetic field
alignment
orbits
stars
causes
pulses
magnetic fields

Keywords

  • binaries: general
  • brown dwarfs
  • instrumentation: photometers
  • stars: low-mass
  • stars: magnetic field
  • stars: rotation

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Harding, L. K., Hallinan, G., Boyle, R. P., Golden, A., Singh, N., Sheehan, B., ... Butler, R. F. (2013). Periodic optical variability of radio-detected ultracool dwarfs. Astrophysical Journal, 779(2), [101]. https://doi.org/10.1088/0004-637X/779/2/101

Periodic optical variability of radio-detected ultracool dwarfs. / Harding, L. K.; Hallinan, G.; Boyle, R. P.; Golden, A.; Singh, Navtej; Sheehan, B.; Zavala, R. T.; Butler, R. F.

In: Astrophysical Journal, Vol. 779, No. 2, 101, 20.12.2013.

Research output: Contribution to journalArticle

Harding, LK, Hallinan, G, Boyle, RP, Golden, A, Singh, N, Sheehan, B, Zavala, RT & Butler, RF 2013, 'Periodic optical variability of radio-detected ultracool dwarfs', Astrophysical Journal, vol. 779, no. 2, 101. https://doi.org/10.1088/0004-637X/779/2/101
Harding LK, Hallinan G, Boyle RP, Golden A, Singh N, Sheehan B et al. Periodic optical variability of radio-detected ultracool dwarfs. Astrophysical Journal. 2013 Dec 20;779(2). 101. https://doi.org/10.1088/0004-637X/779/2/101
Harding, L. K. ; Hallinan, G. ; Boyle, R. P. ; Golden, A. ; Singh, Navtej ; Sheehan, B. ; Zavala, R. T. ; Butler, R. F. / Periodic optical variability of radio-detected ultracool dwarfs. In: Astrophysical Journal. 2013 ; Vol. 779, No. 2.
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