Write a comment
Brown dwarfs are known as "failed stars", owing to the lack of central hydrogen burning. They bridge the gap between planets and stars. Some brown dwarfs are found to maintain kilogauss magnetic fields and produce flaring radio emissions, similar to aurora on magnetized planets in solar system, arousing astronomers' curiosities about their field properties and dynamos.
Radio emissions from Brown dwarfs are known as "failed stars", owing to the lack of central hydrogen burning. They bridge the gap between planets and stars. Some brown dwarfs are found to maintain kilogauss magnetic fields and produce flaring radio emissions, similar to aurora on magnetized planets in solar system, arousing astronomers' curiosities about their field properties and dynamos.
Radio emissions from brown dwarfs reflect their magnetic activities. For solar-type stars, radio, optical and X-ray emissions are all used as magnetic indicators, while for brown dwarfs, optical and X-ray decrease dramatically, and radio becomes the most efficient probe.
Dr. TANG Jing and her colleagues from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) carried out a statistical analysis of radio-flaring brown dwarf population, which helped quantify the potential of finding such objects in FAST surveys.
This study was published in Research in Astronomy and Astrophysics, a peer-reviewed international journal in astronomy and astrophysics supported by NAOC and the Chinese Astronomical Society.
The traditional way is to select a number of brown dwarfs and track them for several hours to catch the possible flares, which is very expensive. Till now, the detected flaring brown dwarfs are less than 20. The so-called Commensal Radio Astronomy FAST Survey (CRAFTS) promises to increase the number by almost one order of magnitude, according to the study.
Led by Dr. LI Di, chief scientist of FAST, CRAFTS utilizes a novel and unprecedented mode to realize simultaneous data taking for pulsar and FRB search, Galactic HI mapping, and HI galaxy study. It is designed to cover 60% of the sky in drift-scan mode.
For FAST, the most significant problem for a point source is the severe confusion due to the large beam size. However, the flaring radio emission is highly circularly polarized, suffering little confusion. Circular polarization can be calculated from the orthogonally polarized outputs, independent of system fluctuation, and is a good method to search for flares.
If we find some highly circularly polarized signal in the survey, we can cross match the archival optical/infrared counterpart for identification. FAST is expected to detect flaring brown dwarfs as far as 180 pc.
Most flaring brown dwarfs are detected at high frequencies. Though some efforts have been made on low frequencies, the flaring emission at L band has not been detected yet. FAST may fill in this gap. If successful, it also bodes well for FAST's potential to discovery exoplanets with strong magnetic fields.
Research Report:The Potential of Detecting Radio-flaring Ultracool Dwarfs at L band in the FAST Drift-scan Survey
Related Links
National Astronomical Observatories
Stellar Chemistry, The Universe And All Within It
|
| Tweet |
| Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution. | ||
| SpaceDaily Monthly Supporter
$5+ Billed Monthly |  | SpaceDaily Contributor
$5 Billed Once credit card or paypal |
Chinese, Australian astronomers detect key process of binary evolution
Beijing (XNA) Jul 10, 2022
A joint research team of Chinese and Australian astronomers has detected a binary star system ejecting a common envelope, a key process of the binary star evolution, which could be of great importance to studies of the expansion of the universe and dark energy. This is the first time that scientists have observed direct evidence of the key process of the evolution of the common envelope of binary stars. The study was published online in the Monthly Notices of the Royal Astronomical Society Thursda ... read more