A magnetic snapshot survey of F-type stars

J. M. Seach , S. C. Marsden , B. D. Carter , C. Neiner (1) , C. P. Folsom (2) , M. W. Mengel , M. E. Oksala (1) , B. Buysschaert (1)

1 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics
2 IRAP - Institut de recherche en astrophysique et planétologie

We present a spectropolarimetric magnetic snapshot survey of 55 stars which includes 53 F-type stars ranging from spectral types F0 to F9 plus 2 chemically peculiar stars β CrB, and δ Cap. We look for magnetic fields in stars spanning a range of effective temperatures where the transition from fossil to dynamo magnetic fields is believed to occur. High-resolution spectropolarimetry using circularly polarized spectra is used to look for a magnetic detection in the Stokes V profile, determine the mean longitudinal magnetic field (B_l), and to look for correlations with stellar parameters. Surface magnetic fields are detected on 14 F-stars, and present in every spectral class from F3V-F9V ranging in strength from 0.3 ± 0.1 G (36 UMa, F8V) to 8.3 ± 0.9 G (h Dra, F8V). Thus we find photospheric magnetic fields are present in stars as early as spectral type F3V with an outer convection zone thickness less than a few per cent of the stellar radius.

Mots clés: stars: early-type; stars: late-type; stars: magnetic field

Domaines: Planète et Univers [physics]

J. M. Seach, S. C. Marsden, B. D. Carter, C. Neiner, C. P. Folsom, et al.. A magnetic snapshot survey of F-type stars. Monthly Notices of the Royal Astronomical Society, 2020, 494, pp.5682-5703. ⟨10.1093/mnras/staa1107⟩. ⟨insu-03673144⟩