Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First evidence of a magnetic field on Vega. Towards a new class of
  magnetic A-type stars   We report the detection of a magnetic field on Vega through
spectropolarimetric observations. We acquired 257 Stokes V, high
signal-to-noise and high-resolution echelle spectra during four consecutive
nights with the NARVAL spectropolarimeter at the 2-m Telescope Bernard Lyot of
Observatoire du Pic du Midi (France). A circularly polarized signal in line
profiles is unambiguously detected after combining the contribution of about
1200 spectral lines for each spectrum and summing the signal over the 257
spectra. Due to the low amplitude of the polarized signal, various tests have
been performed to discard the possibility of a spurious polarized signal. They
all point towards a stellar origin of the polarized signal. Interpreting this
polarization as a Zeeman signature leads to a value of $-0.6 \pm 0.3$ G for the
disk-averaged line-of-sight component of the surface magnetic field. This is
the first strong evidence of a magnetic field in an A-type star which is not an
Ap chemically peculiar star. Moreover, this longitudinal magnetic field is
smaller by about two orders of magnitude than the longitudinal magnetic field
(taken at its maximum phase) of the most weakly magnetic Ap stars. Magnetic
fields similar to the Vega magnetic field could be present but still undetected
in many other A-type stars.

29
The categories of this paper are: funct-an
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph