Update on Flare Stars WG activities

Rachel Osten
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. Flare Stars Working Group Update Rachel Osten LOFAR TKP meeting Dec. 14, 2011 Meudon (virtually) Tuesday, December 13, 2011
2. Main Items • Science Goals • Recent Activity • Future Activity VLA full sun image at 330 MHz; image courtesy S. White Tuesday, December 13, 2011
3. Science Goals • study the plasma astrophysics occurring in cool, magnetically active stars - characterize nature of accelerated particle population in stellar flares - constrain rate of coronal mass ejections in high flaring rate stars - apply knowledge to radio transients classification • expect emissions to be coherent in nature, produced either from plasma radiation (ν∝sνp, with νp ∼9000√ne Hz) or cyclotron maser emission (ν∝sνB, with νB ∼2.8 B MHz) Tuesday, December 13, 2011
4. The Sun is the starting point for expectations about low frequency stellar radio emission example type III bursts example type II burst+(type IV also) Tuesday, December 13, 2011
5. Focus on 3 classes of magnetically active stars showing evidence for coherent emission at cm wavelengths Tuesday, December 13, 2011
6. ultracool dwarfs Focus on 3 classes of magnetically active stars showing evidence for coherent emission at cm wavelengths Tuesday, December 13, 2011
7. ultracool dwarfs active binaries Focus on 3 classes of magnetically active stars showing evidence for coherent emission at cm wavelengths Tuesday, December 13, 2011
8. ultracool dwarfs M dwarf flare stars active binaries Focus on 3 classes of magnetically active stars showing evidence for coherent emission at cm wavelengths Tuesday, December 13, 2011
9. Science in Drifting Stellar Radio Bursts • radiating elements with intrinsic drift in the atmosphere, producing plasma radiation locally; dν/dt ∝ν • radiating elements with intrinsic drift, producing cyclotron maser emission locally; dν/dt ∝ν-4/3 • ISM effects dν/dt∝ν3 Tuesday, December 13, 2011
10. Observational Strategy • two phases: - targeted approach to learning about the diversity of behavior in 3 different classes of stars (active binaries, dMe flare stars, ultracool dwarfs) - use results and extend to serendipitous detections in Radio Sky Monitor Tuesday, December 13, 2011
11. Recent Activity • NSF proposal submitted to fund a post-doc in commissioning/science activities (3 yrs) • tied-array beam observations of a nearby M dwarf flare star (d=5 pc) AD Leo done over the summer, being looked at Tuesday, December 13, 2011
12. Future Activity • digest commissioning data • other observations? • simultaneous observations with LWA1? Tuesday, December 13, 2011