Credit: ESO/IRAP-CNRS-UPS/A.Klotz
An unusual new video
sequence shows the rapid brightening and slower fading of a supernova
explosion in the galaxy NGC 1365. The supernova, which has been named SN
2012fr, was discovered by French astronomer Alain Klotz on the 27
October 2012. The images captured by the small TAROT robotic telescope,
located at ESO’s La Silla Observatory in Chile, have been compiled to
create this unique movie.
Supernovae are the results of the explosive and cataclysmic deaths of
certain types of stars. They are so brilliant that they can outshine
their entire parent galaxy for many weeks before slowly fading from
sight.
The supernova 2012fr [1]
was discovered by Alain Klotz on the afternoon of 27 October 2012. He
was busy measuring the brightness of a faint variable star in an image
from the TAROT
(Télescope à Action Rapide pour les Objets Transitoires) robotic
telescope at ESO’s La Silla Observatory, when he noticed a new object
that was not present in an image taken three days earlier. After
checking with telescopes and astronomers all across the world the bright
object was confirmed to be a Type Ia supernova.
Some stars co-habit with a second star, both orbiting around a common
centre of gravity. In some cases one of them might be a very old white
dwarf that is stealing material from its companion. At some point the
white dwarf has siphoned off so much matter from its companion that it
becomes unstable and explodes. This is known as a Type Ia supernova.
This kind of supernova has become very important as they are the most
reliable way of measuring distances to very remote galaxies in the
early Universe. Beyond the local group of galaxies, astronomers needed
to find very bright objects with predictable properties that could act
as signposts to help them map out the expansion history of the Universe.
Type Ia supernovae are ideal as their brightnesses peak and fade in
almost the same way for each explosion. Measurements of the distances to
Type Ia supernovae led to the discovery of the accelerating expansion
of the Universe, work that was awarded the Nobel Prize for Physics in 2011.
The host galaxy of this supernova is NGC 1365 (see also potw1037a), an elegant barred spiral galaxy, located 60 million light-years away towards the constellation of Fornax (The Furnace). With its diameter of about 200 000 light-years,
it stands out among the other galaxies in the Fornax cluster. A
colossal straight bar runs through the galaxy, containing the nucleus at
the centre. The new supernova can be easily spotted just above the
core, in the middle of the image.
Astronomers discovered more than 200 new supernovae in 2012, of which
SN 2012fr is among the brightest. The supernova was first spotted when
it was very faint on the 27 October 2012, and it reached its peak
brightness on 11 November 2012 [2].
It was then easily seen as a faint star through a medium-sized amateur
telescope. The video was compiled from a series of images taken of the
galaxy over a period of three months, from the discovery in October
until mid-January 2013.
TAROT
is a 25-centimetre optical robotic telescope, able to move very fast,
and to start an observation within a second. It was installed at La
Silla Observatory in 2006 with the purpose of detecting cosmic gamma-ray
bursts. The images that revealed SN 2012fr were captured using blue,
green and red filters.
Notes
[1] Supernovae are designated by the year in which
they are discovered, and the order in which they are discovered during
that year, by using letters of the alphabet. The fact that the the
supernova was discovered by a French team and it has been designated by
the letters “fr” is pure coincidence.
[2] At this time it was magnitude 11.9. This is about
200 times too faint to see with the unaided eye even on a clear and
dark night. But if the supernova at its peak brightness and our star the
Sun were seen together at the same distance from the observer the
supernova would appear about 3000 million times brighter than the Sun.
Links
- Video: TAROT discovers a bright supernova in NGC 1365
- Video: TAROT discovers a bright supernova in NGC 1365 (excerpt)
Contacts
Alain KlotzInstitut de Recherche en Astrophysique et Planetologie
Toulouse, France
Tel: +33 05 61 55 66 66
Email: alain.klotz@irap.omp.eu
Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
