Aurora found on the ultra cool dwarf LSR J1835+3259

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Aurora found on the ultra cool dwarf LSR J1835+3259

Post by Stalker on 30th July 2015, 3:48 am

Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence
Aurorae are detected from all the magnetized planets in our Solar System, including Earth1. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons2, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere3. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs.

http://www.astronomy.com/news/2015/07/astronomers-discover-powerful-aurora-beyond-solar-system
http://www.space.com/30087-alien-auroras-found-beyond-solar-system.html
http://www.skyandtelescope.com/astronomy-news/aurora-on-a-dwarf-star-0729201523/

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Re: Aurora found on the ultra cool dwarf LSR J1835+3259

Post by Lazarus on 30th July 2015, 12:18 pm

Interesting. I wonder where the particles powering the aurora are coming from. An Io-like planet would be nice, but not sure if that works given the synchrony with the BD rotation.
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Re: Aurora found on the ultra cool dwarf LSR J1835+3259

Post by Stalker on 30th July 2015, 1:38 pm

The Io like planet doest need to be synchronous with BD rotation.

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Re: Aurora found on the ultra cool dwarf LSR J1835+3259

Post by Lazarus on 30th July 2015, 2:52 pm

Thing is, the radio and visible variations seem to exhibit the same period. In the case of Jupiter, the radio emissions show periodicity associated with the orbital phase of Io. I'm not sure that a ~2.84 hour orbit would be outside the Roche limit (haven't done the calculations to check), so unless there's another period in the emissions then I doubt it's a Jupiter-Io analogue system.
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Re: Aurora found on the ultra cool dwarf LSR J1835+3259

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