Magnetic field and prominences of the young, solar-like, ultra-rapid rotator V530 Persei

Abstract

Context. Young solar analogs reaching the main sequence experience very strong magnetic activity, generating angular momentum losses through wind and mass ejections. Aims. We investigate signatures of magnetic fields and activity at the surface and in the prominence system of the ultra-rapid rotator V530 Per, a G-type solar-like member of the young open cluster α Persei. This object has a rotation period that is shorter than all stars with available magnetic maps. Methods. With a time-series of spectropolarimetric observations gathered with ESPaDOnS over two nights on the Canada-France-Hawaii Telescope, we reconstructed the surface brightness and large-scale magnetic field of V530 Per using the Zeeman-Doppler imaging method, assuming an oblate stellar surface. We also estimated the short term evolution of the brightness distribution through latitudinal differential rotation. Using the same data set, we finally mapped the spatial distribution of prominences through tomography of the Hα emission. Results. The brightness map is dominated by a large, dark spot near the pole, accompanied by a complex distribution of bright and dark features at lower latitudes. Taking the brightness map into account, the magnetic field map is reconstructed as well. Most of the large-scale magnetic field energy is stored in the toroidal field component. The main radial field structure is a positive region of about 500 G, at the location of the dark polar spot. The brightness map of V530 Per is sheared by solar-like differential rotation, with roughly a solar value for the difference in rotation rate between the pole and equator. It is important to note that Hα is observed in emission and it is mostly modulated by the stellar rotation period over one night. The prominence system is organized in a ring at the approximate location of the corotation radius, and displays significant evolution between the two observing nights. Conclusions. V530 Per is the first example of a solar-type star to have its surface magnetic field and prominences mapped together, which will bring important observational constraints to better understand the role of slingshot prominences in the angular momentum evolution of the most active stars.

The evolution of the solar wind

“…As I will discuss later on, we expect that active stars have hotter winds. These conditions are more easily met in fast and ultrafast rotators, in agreement with extended prominences seen in the ultrafast rotators such as Speedy Mic (Jeffries 1993;Dunstone et al 2006), HQ Lup (Donati et al 2000) and, more recently, in V530 Per (Cang et al 2020), all of which with rotation periods \0:4 d. Slingshot prominences have been predicted to occur in stars that are rotating at less extreme rates as well, such as in the young Sun HIP 12545 (Villarreal D'Angelo et al 2018b), which shows a rotation period of nearly 5 days.…”

The evolution of the solar wind

“…As I will discuss later on, we expect that active stars have hotter winds. These conditions are more easily met in fast and ultrafast rotators, in agreement with extended prominences seen in the ultrafast rotators such as Speedy Mic (Jeffries 1993;Dunstone et al 2006), HQ Lup (Donati et al 2000) and, more recently, in V530 Per (Cang et al 2020), all of which with rotation periods < 0.4 d. Slingshot prominences have been predicted to occur in stars that are rotating at less extreme rates as well, such as in the young Sun HIP 12545 (Villarreal D'Angelo et al 2018b), which shows a rotation period of nearly 5 days.…”

Simultaneous photometric and CARMENES spectroscopic monitoring of fast-rotating M dwarf GJ 3270

“…Slingshot prominences are comprised of trapped, cool, gas and appear as absorption transients in Hα. Slingshot prominences are thought to be most common around zero age main-sequence stars (Jardine et al 2020;Cang et al 2020). If such a prominence was present prior to flare 2, it was likely disrupted or ejected by that flare because no similarly A105, page 13 of 18 A&A 651, A105 (2021) sized absorption transients are seen for the rest of our observational period.…”