Hubble pinpoints red supergiant that exploded

Jul 29, 2005
Hubble supernova

A series of lucky breaks has allowed two University of California, Berkeley, astronomers to track down the identity of a distant star that lit up the majestic Whirlpool Galaxy a month ago.

While astronomers can predict which stars will end their lives in a fiery explosion, surprisingly only five supernovas before now had been traced back to a known star, according to one of the astronomers, UC Berkeley astronomy professor Alex Filippenko. Most supernovas are too distant, or their progenitor stars too faint or in too crowded fields for astronomers to look back in historical sky photos in order to pinpoint the location and type of star.

The Space Telescope Science Institute (STScI) today (Thursday, July 28) released photos of the beautiful Whirlpool Galaxy, M51, showing the location of the original star and the bright supernova just 12 days after its explosion was discovered.

The supernova, dubbed SN 2005cs, belongs to a class of exploding stars called "Type II-plateau." A supernova of this type results from the collapse and subsequent explosion of a massive star whose light remains at a constant brightness (a "plateau") for a period of time.

This finding is consistent with the idea that the progenitors of supernova explosions are red, supergiant stars with masses eight to 15 times the sun's mass. The progenitor star of SN 2005cs was found to be at the low end of the mass range for supernova explosions. Stars with masses lower than eight solar masses do not explode as supernovae at all, but rather blow off their outer atmospheres to become planetary nebulae before contracting to white dwarfs.

A German amateur astronomer was the first to note the unusually bright star - perhaps a supernova - in M51, and he asked the staff at the Central Bureau for Astronomical Telegrams to post a note to that effect on June 29. Filippenko, who specializes in supernovae and black holes, received the notice late that afternoon and rushed to get one of his former students to request a spectrum of the brightly burning star from a telescope in Arizona. This spectrum confirmed that it was a Type II supernova.

Filippenko, by chance, was at the very end of a year-long observational program using the Hubble Space Telescope, and he worked during an overnight flight and early the next morning to submit a request to observe the supernova before his opportunity ended at 5 p.m. Eastern time June 30. Since Hubble can easily resolve stars in nearby galaxies, such as the Whirlpool, it was the only chance he had to track down the exploding star's identity. The new picture was needed for comparison with archival images in order to accurately determine the position of the supernova.

He got in under the wire, convincing the telescope crew to observe the waning supernova on July 11, amidst the hoopla and frequent observations of the Deep Impact probe's collision with comet Temple I.

"This will be one of Hubble's many legacies," Filippenko said. "No other telescope program could observe the exact location of this Type II supernova, yet it was an opportunity not to be missed."

From the brand new Hubble image and a January 2005 image Hubble had taken of the Whirlpool Galaxy, UC Berkeley research astronomer Weidong Li and Filippenko were able to pinpoint the location of the progenitor star and identify it as a red supergiant whose mass is about seven to 10 times that of the sun.

"This is a great example of the excitement of science, when something happens and you have to jump on it right away," said Filippenko, who is known for the enthusiasm he brings to teaching. "Some nights you just don't sleep."

Filippenko, Li and colleague Schuyler Van Dyk of Caltech's Spitzer Science Center first reported their findings in IAU circulars 8556 and 8565 on July 3 and July 12, respectively. The team submitted a full paper describing their research to The Astrophysical Journal on July 18.

The Space Telescope Science Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., under contract with the Goddard Space Flight Center, Greenbelt, Md. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.

Source: UC Berkeley

Explore further: Image: The colors of sunset over the ISS

add to favorites email to friend print save as pdf

Related Stories

Dwarf galaxy that reveals the history of the universe

Mar 24, 2015

The first galaxies were formed some 13.3 billion years ago, mainly composed of hydrogen and helium, the primary elements that emerged from the Big Bang. Their study to date has been technically very challenging ...

Milky Way's center unveils supernova 'dust factory'

Mar 19, 2015

Sifting through the center of the Milky Way galaxy, astronomers have made the first direct observations - using an infrared telescope aboard a modified Boeing 747 - of cosmic building-block dust resulting ...

"Mini supernova" explosion could have big impact

Mar 16, 2015

In Hollywood blockbusters, explosions are often among the stars of the show. In space, explosions of actual stars are a focus for scientists who hope to better understand their births, lives, and deaths and ...

A grand extravaganza of new stars

Mar 11, 2015

This dramatic landscape in the southern constellation of Ara (The Altar) is a treasure trove of celestial objects. Star clusters, emission nebulae and active star-forming regions are just some of the riches ...

Image: The twisted shockwaves of an exploded star

Mar 09, 2015

Discovered on 5 September 1784 by astronomer William Herschel, the Veil Nebula was once a star. Now it is a twisted mass of shock waves that appears six times larger than the full Moon in the sky.

How far back are we looking in time?

Mar 06, 2015

The Universe is a magic time window, allowing us to peer into the past. The further out we look, the further back in time we see. Despite our brains telling us things we see happen at the instant we view ...

Recommended for you

Russian, American ready for a year in space

9 hours ago

The Russian astronaut heading off for a year in space says he'll miss the natural landscapes on Earth. His American counterpart jokes he won't miss his twin brother.

Galaxy clusters collide—dark matter still a mystery

14 hours ago

When galaxy clusters collide, their dark matters pass through each other, with very little interaction. Deepening the mystery, a study by scientists at EPFL and the University of Edinburgh challenges the ...

Using 19th century technology to time travel to the stars

19 hours ago

In the late 19th century, astronomers developed the technique of capturing telescopic images of stars and galaxies on glass photographic plates. This allowed them to study the night sky in detail. Over 500,000 ...

Image: The colors of sunset over the ISS

21 hours ago

ESA astronaut Samantha Cristoforetti took these images from the International Space Station during her six-month mission. The Progress cargo ship and Soyuz crew spacecraft reflect sunlight as our star sets ...

Feud on Earth but peace in space for US and Russia

Mar 26, 2015

Hundreds of kilometres below on Earth, their governments are locked in a standoff over Ukraine—but up in space, Russian cosmonauts and American astronauts are still working together side by side.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.