Physics Photo of the Week
May 6, 2011
April 28, 2011 the American Association of Variable Star Observers sent
out an alert notice of a new type Ia supernova in the distant galaxy
NGC 2972. The weather had just cleared after a week of clouds and
rain and students were anxious* to observe with the WWC telescope and
CCD camera. The supernova is seen as the bright star in the
elongated galaxy in the upper left center of the image. Zhangwei
Jin, Ningbo, Zhejiang, China, and Xing Gao, Urumqi, Xinjiang, China
discovered this supernova on April 26, 2011. At their website, http://www.xjltp.com/XOSS/XM20ZJ/XM20ZJ.htm,
can view this galaxy about 2 weeks earlier before the supernova
erupted as well as the discovery image.
Supernovae are rather rare events. It is estimated that in a
typical galaxy consisting of 1012 stars there is about one
supernova event per century, where a star blows up becoming more than 4
x 109 times (that's 4 billion times) the luminosity of the
Supernovae, especially type Ia supernovae, are important in astronomy
because every type Ia supernova is the same brightness (4 x
109 times the luminosity of the Sun). That is because
such a supernova explosion occurs when a white dwarf star (in a close
binary association with an ordinary star) pulls enough material from
the companion star that it reaches the Chandrasekhar limit of 1.4 solar
masses upon which it blows up. Because of the standard
brightness, we can use these events to easily calculate the distance to
the supernova - hence the distance to the host galaxy. This
supernova is still brightening and expected to reach its maximum
brightness in about 2 to 3 weeks. Estimating the brightness from
data available from the AAVSO it is estimated that this galaxy is about
60 million light years distant. This event happened about the
same time that the dinosaurs became extinct on the Earth.
*Students Rashad Ali, Josiah Blocker,
Joshua Jenkinson, Kathryn Kipfer, Taylor Moore, and Cristal Stevens
helped with the telescope to obtain this image of the supernova on
April 28 and April 29, 2011. I will continue to observe this
object through May and June to measure its brightness and to send the
data to AAVSO. On clear nights, people may visit the Spidel
Observatory - the yard outside the physics lab.
Photo of the
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature interesting phenomena in
the world around us. Students, faculty, and others are invited to
submit digital (or film) photographs for publication and
explanation. Atmospheric phenomena are especially welcome.
Please send any photos to email@example.com.
All photos and discussions are copyright by Donald
Collins or by the person credited for the photo and/or
discussion. These photos and discussions may be used for private
individual use or educational use. Any commercial use without
written permission of the photoprovider is forbidden.
see the Physics Photo
the Week Archive.
Observers are invited to submit
digital photos to: