Study discards possibility that type Ia supernovae might stem from
explosions of white dwarfs nourished by normal stars. Were these
conclusions to become generalized, type Ia supernovae might no longer
serve as “standard candles” to measure astronomical distances
Type Ia supernovae happen when a white dwarf, the “corpse” of a star similar to the Sun, absorbs material from a twin star until it reaches a critical mass--1.4 times that of the Sun—and explodes. Because of their origin, all these explosions share a very similar luminosity. This uniformity made type Ia supernovae ideal objects to measure distances in the universe, but the study of supernova 2014J suggests a scenario that would invalidate them as “standard candles".
"Type Ia supernovae are considered standard candles because their constitution is very homogeneous and practically all of them reach the same maximum luminosity. They even allowed us to discover that the universe was expanding at an accelerating rate. However, we still don’t know what stellar systems give rise to this type of supernovae,” says Miguel Ángel Pérez Torres, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) in charge of the study.
Type Ia supernovae happen when a white dwarf, the “corpse” of a star similar to the Sun, absorbs material from a twin star until it reaches a critical mass--1.4 times that of the Sun—and explodes. Because of their origin, all these explosions share a very similar luminosity. This uniformity made type Ia supernovae ideal objects to measure distances in the universe, but the study of supernova 2014J suggests a scenario that would invalidate them as “standard candles".
"Type Ia supernovae are considered standard candles because their constitution is very homogeneous and practically all of them reach the same maximum luminosity. They even allowed us to discover that the universe was expanding at an accelerating rate. However, we still don’t know what stellar systems give rise to this type of supernovae,” says Miguel Ángel Pérez Torres, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) in charge of the study.
A new model postulating the fusion of two white dwarfs is now
challenging the predominant one, consisting of a white dwarf and a
normal star. The new scenario does not imply the existence of a maximum
mass limit and will not, therefore, necessarily produce explosions of
similar luminosity. Credit: NASA/CXC/M Weiss
Credit: NASA/CXC/M Weiss
SN 2014J, A SUPERNOVA VERY NEAR BY
SN 2014J, A SUPERNOVA VERY NEAR BY
The results mentioned above were obtained from the study of supernova
2014J, situated 11.4 million light years away from our planet, using the
EVN and eMERLIN networks of radio telescopes. “It is a phenomenon that
very seldom occurs in our immediate universe. 2014J has been the Ia type
supernova closest to us since 1986, when the telescopes were much less
sensitive, and it may well be the only one we’ll be able to observe in
such vicinity in the next one hundred and fifty years,” says Pérez
Torres (IAA-CSIC).
Radio observation makes it possible to reveal what stellar systems lie
behind type Ia supernovae. If the explosion proceeds from a white dwarf
being nourished by a twin star, for example, a great amount of gas
should be present in the environment; after the explosion, the material
ejected by the supernova will collide with this gas and produce an
intense emission of X rays and radio waves. By contrast, a couple of
white dwarfs will not generate this gaseous envelope and, therefore,
there will be no emission of either X rays or radio waves.
"We have not detected radio emissions on SN 2014J, which favours the
second scenario", says Pérez Torres. "If these results were to gain
general acceptance, the cosmological consequences would be weighty,
because the use of type Ia supernovae to measure distances would come
into question,” the researcher concludes.
Reference
M. A. Perez-Torres, P. Lundqvist, R. J. Beswick, C. I. Bjornsson, T. W. B. Muxlow, Z. Paragi, S. Ryder, A. Alberdi, C. Fransson, J. M. Marcaide, I. Marti-Vidal, E. Ros, M. K. Argo, J. C. Guirado. Constraints on the progenitor system and the environs of SN 2014J from deep radio observations. The Astrophysical Journal. ApJ, vol. 792, pág. 38.Contact:
Instituto de Astrofísica de Andalucía (IAA-CSIC)Unidad de Divulgación y Comunicación
Silbia López de Lacalle - sll@iaa.es - 958230532
http://www.iaa.es
http://www-divulgacion.iaa.es
