Presentation Title

Tuning Into Brown Dwarfs: Long-Term Radio Monitoring of Two Very Low Mass Dwarfs

Faculty Mentor

Adam Burgasser, Carl Melis

Start Date

18-11-2017 2:15 PM

End Date

18-11-2017 2:30 PM

Location

9-279

Session

Physical Sciences 1

Type of Presentation

Oral Talk

Subject Area

physical_mathematical_sciences

Abstract

The very lowest-mass (VLM) stars and brown dwarfs, with effective temperatures T < 3000 K, exhibit mixed magnetic activity trends, with H-alpha and X-ray emission that declines rapidly beyond type M7/M8, but persistent radio emission in roughly 10-20% of sources. The dozen or so VLM radio emitters known show a broad range of emission characteristics and time-dependent behavior, including steady persistent emission, periodic oscillations, periodic polarized bursts, and aperiodic flares. Understanding the evolution of these variability patterns, and in particular, whether they undergo solar-like cycles, requires long-term monitoring. We report the results of a long-term JVLA monitoring program of two magnetically-active VLM dwarf binaries, the young M7 2MASS 1314+1320AB and older L5 2MASS 1315-2649AB. On long timescales, 2MASS 1314 shows repeated flaring while 2MASS 1315 appears to be a quiescent emitter slowly declining in brightness from a peak at the start of our observations. On shorter timescales, both sources show significant variability over just a few days. These results suggest long-term radio behavior in radio-emitting VLM dwarfs is just as diverse and complex as short-term behavior.

Summary of research results to be presented

On long-term timescales, 2MASS 1314 shows repeated flaring while 2MASS 1315 appears to be a quiescent emitter slowly declining in brightness. When including data from previous observations of 2MASS 1315, its brightness has dropped over 200 muJy since its first detection in 2011, which hints towards a long-term (>8 years) cycle. On shorter timescales, both sources show significant variability over just a few days and even within the observation times. These results suggest long-term radio behavior in radio-emitting VLM dwarfs is just as diverse and complex as short-term behavior.

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Nov 18th, 2:15 PM Nov 18th, 2:30 PM

Tuning Into Brown Dwarfs: Long-Term Radio Monitoring of Two Very Low Mass Dwarfs

9-279

The very lowest-mass (VLM) stars and brown dwarfs, with effective temperatures T < 3000 K, exhibit mixed magnetic activity trends, with H-alpha and X-ray emission that declines rapidly beyond type M7/M8, but persistent radio emission in roughly 10-20% of sources. The dozen or so VLM radio emitters known show a broad range of emission characteristics and time-dependent behavior, including steady persistent emission, periodic oscillations, periodic polarized bursts, and aperiodic flares. Understanding the evolution of these variability patterns, and in particular, whether they undergo solar-like cycles, requires long-term monitoring. We report the results of a long-term JVLA monitoring program of two magnetically-active VLM dwarf binaries, the young M7 2MASS 1314+1320AB and older L5 2MASS 1315-2649AB. On long timescales, 2MASS 1314 shows repeated flaring while 2MASS 1315 appears to be a quiescent emitter slowly declining in brightness from a peak at the start of our observations. On shorter timescales, both sources show significant variability over just a few days. These results suggest long-term radio behavior in radio-emitting VLM dwarfs is just as diverse and complex as short-term behavior.