Space Weather & Heliophysics

On The Radio Emission From ε Eridani

By Keith Cowing
Status Report
September 7, 2023
Filed under , , , ,
On The Radio Emission From ε Eridani
10.0 GHz image of ϵ Eridani for the epoch 2020 Apr 15. Contours are -4, -3, 3, 4, 5, 6, 8, 10, 12 and 15 times 4.0 µJy beam−1, the rms noise in this region of the image. The synthesized beam (3.′′48 × 2.′′12; PA = 6.7◦ ) is shown in the bottom left corner. The cross marks the position of the optical star from the Gaia Early Data Release 3 (Gaia EDR3), corrected for the proper motions of the source (Gaia Collaboration 2020). — astro-ph.SR

Some solar-type stars are known to present faint, time-variable radio continuum emission whose nature is not clearly established.

We report on Jansky Very Large Array observations of the nearby star ϵ Eridani at 10.0 and 33.0 GHz. We find that this star has flux density variations on scales down to days, hours and minutes. On 2020 Apr 15 it exhibited a radio pulse at 10.0 GHz with a total duration of about 20 minutes and a peak four times larger than the plateau of 40 μJy present in that epoch.

We were able to model the time behavior of this radio pulse in terms of the radiation from shocks ramming into the stellar wind. Such shocks can be produced by the wind interaction of violently expanding gas heated suddenly by energetic electrons from a stellar flare, similar to the observed solar flares. Because of the large temperature needed in the working surface to produce the observed emission, this has to be non thermal.

It could be gyrosynchrotron or synchrotron emission. Unfortunately, the spectral index or polarization measurements from the radio pulse do not have enough signal-to-noise ratio to determine its nature.

Luis F. Rodriguez, Susana Lizano, Jorge Canto, Ricardo F. Gonzalez

Comments: 7 pages, 4 figures. To appear in Astronomy & Astrophysics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2309.03862 [astro-ph.SR] (or arXiv:2309.03862v1 [astro-ph.SR] for this version)
Submission history
From: Luis F. Rodriguez
[v1] Thu, 7 Sep 2023 17:24:53 UTC (88 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻