A&A press release: Magnetic field on bright star Vega (23 June 2009)
- Details
- Published on 22 June 2009
A&A press release
Released on June 23rd, 2009
Magnetic field on bright star Vega |
Based on the article:
“First
evidence of a magnetic field on Vega. Towards a new class of magnetic
A-type stars”, by F. Lignières, P. Petit, T.
Böhm, and M. Aurière
Published in Astronomy & Astrophysics, 2009, vol. 500-3
Astronomy &
Astrophysics publishes the first detection of a magnetic
field on the bright star Vega. Using the NARVAL spectropolarimeter of
the Bernard-Lyot telescope on top of the Pic du Midi (France),
astronomers clearly observe the magnetically-induced effect in the
spectrum of Vega, thereby showing that the star possesses a magnetic
field, something unknown so far.
Astronomy & Astrophysics is publishing the first
detection of a magnetic field on the star Vega, one of the brightest
stars in the sky. Using the high-sensitivity NARVAL spectropolarimeter
installed at the Bernard-Lyot telescope (Pic du Midi Observatory,
France), a team of astronomers [1] detected the effect of a magnetic
field (known as the Zeeman effect) in the light emitted by Vega.

Fig. 1 - Bernard-Lyot Telescope, on top of the Pic du Midi de Bigorre (France). © Pascal Petit
This time, astronomers analyzed the polarization of light emitted by Vega [2] and detected a weak magnetic field at its surface. This is really not a big surprise because one knows that the charged particle motions inside stars can generate magnetic fields, and this is how solar and terrestrial magnetic fields are produced. However, for more massive stars than the Sun, such as Vega, theoretical models cannot predict the intensity and the structure of the magnetic field, so that astronomers had no clue to the strength of the signal they were looking for. After many unsuccessful attempts in past decades, both the high sensitivity of NARVAL and the full dedication of an observing campaign to Vega have made this first detection possible.
The strength of Vega magnetic field is about 50 micro-tesla, which is close to that of the mean field on Earth and on the Sun. This first observational constraint opens the way to in-depth theoretical studies about the origin of magnetic fields in massive stars. This detection also suggests that magnetic fields exist but have not been detected yet on many stars like Vega, but farther and more difficult to observe. Astronomers believe that this discovery will be a key step in understanding stellar magnetic fields and their influence on stellar evolution. As for Vega, it is now the prototype of a new class of magnetic stars and will definitely continue fascinating astronomers for years.
[1] The team includes F. Lignières, P. Petit, T. Böhm, and M. Aurière (Laboratoire d'Astrophysique de Toulouse-Tarbes, CNRS/Université de Toulouse, France).
[2] Radiation is not only characterized by its wavelength and its intensity, but also by its polarization state. The polarization state of waves, including light waves, describes the orientation of their vibrations. A light wave can either be non-polarized, linearly or circularly polarized depending on the orientation of the electric field as the wave travels. In particular, the polarization state of radiation gives information about the presence of a magnetic field in the medium where the radiation was emitted. Hence, polarization data allow astronomers to study stellar magnetic fields.
First evidence of a magnetic field on Vega. Towards a new class of magnetic A-type stars, by F. Lignières, P. Petit, T. Böhm, and M. Aurière.
To be published in Astronomy & Astrophysics,
2009, vol. 500-3
Full article available in PDF
format
A French press release from SRON is available at http://www.insu.cnrs.fr/
Contacts:
- Science:
Dr.
François Lignières
Observatoire Midi-Pyrénées, France
Email: ligniere (at) ast.obs-mip.fr
Phone: +33 (0)5 61 33 28 98
Observatoire Midi-Pyrénées, France
Email: pascal.petit (at) ast.obs-mip.fr
Phone: +33 (0)5 61 33 28 28
Dr. Törsten Böhm
Observatoire Midi-Pyrénées, France
Email: boehm (at) obs-mip.fr
Phone: +33 (0)5 61 33 28 32
- Press office:
Dr.
Jennifer Martin
Astronomy & Astrophysics
61, avenue de l'Observatoire
75014 Paris, France
Email: aanda.paris (at) obspm.fr
Phone: +33 1 43 29 05 41
© Astronomy & Astrophysics 2009