Revealing mysteries in our neighbouring system

By Carlos Eiroa of the Universidad Autónoma de Madrid

An international research team headed by Carlos Eiroa, researcher at Universidad Autónoma de Madrid, have measured the 'minimum temperature region' of Alpha Centauri A, the closest star system to Earth.

This measure is essential to understand stellar atmospheres, and it is the first time that it has been calculated for a different star than ours. Observations were taken with the Herschel and APEX space telescopes.

“The minimum temperature region of a star is essential to understand the basic physics of stellar atmospheres”, says Carlos Eiroa, Theoretical Physics professor at the Universidad Autónoma de Madrid (UAM) and one of the authors of the study.

"Stellar atmospheres are characterized by an average temperature, although strictly speaking, they have a temperature gradient. Initially, the temperature decreases through the atmospheric region called 'photosphere', reaching a minimum value. Subsequently the temperature begins to rise again. This temperature inversion can only be directly observed in the far infrared wavelength", adds the researcher.

Alpha Centauri is the closest star system to Earth. It is about 4.3 light years away and it is composed of three stars. An Earth-mass planet was found orbiting one of the stars known as Alpha Centaury B.

Now, scientists were able to characterize the temperature minimum region in the brightest star, the Alpha Centauri A. This is slightly brighter, larger and older than the Sun. The measurement was possible thanks to the Herschel space telescope, an instrument of the European Space Agency (ESA) that can catch the far infrared; and the APEX telescope, an instrument used by the European Southern Observatory (ESO) in Chile to measure millimeter and micrometer wavelengths.

The results were recently published published in the Astronomy and Astrophysics Letters by the DUNES consortium (Dust Around Nearby Stars), an international team of about 50 scientists led by Carlos Eiroa, which aims to find and characterize exozodiacal disks (similar to the Kuiper belt) in different planetary systems than our own. The first author is the Swedish astrophysicist René Liseau, from Chalmers University of Technology (Onsala, Sweden).

Universidad Autónoma de Madrid
www.atomiumculture.eu

 

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Bibliographic Reference: R. Liseau, B. Montesinos, G. Olofsson, G. Bryden, J. P. Marshall, D. Ardila, A. Bayo Aran, W. C. Danchi, C. del Burgo, C. Eiroa, S. Ertel, M. C. W. Fridlund, A. V. Krivov, G. L. Pilbratt, A. Roberge, P. Thébault, J. Wiegert and G. J. White17,18. Centauri A in the far infrared, Astronomy and Astrophysics, Volume 549, January 2013.