Stretching over 300 light-years from the supernova remnant
Space news (astrophysics: supernovae; Cassiopeia A remnant) – 11,000 light-years from Earth toward the northern constellation Cassiopeia the Queen –
On the day in 1667 when a brilliant new star appeared in the sky in Cassiopeia the Queen, no written account is left to tell of the stellar event. The supernova remnant left over is called Cassiopeia A. It consists of a neutron star, with the first carbon atmosphere ever detected, and an expanding shell of material that was ejected from the star as it contracted under its own mass. The progenitor star of this supernova remnant was a supermassive star estimated to be between 15 to 20 times as massive as Sol.
The composite image of the Cassiopeia A supernova remnant seen above was made using six processed images taken over a three year period by NASA’s Spitzer Space Telescope. It shows the largest light echoes ever detected at over 300 light-years in length, which were created as light from the explosion passed through clumps of dust surrounding the supernova remnant. This light illuminated and heated surrounding dust clumps, making them briefly glow in infrared, like a series of colored lights lighting up one after the other. This resulted in an optical illusion in which the dust appears to be traveling away from the remnant at the speed of light. This apparent motion is represented in this image by different dust colors, with dust features unchanged over time appearing gray, and changes in surrounding dust over time represented by blue or orange colors.
Supernova remnant Cassiopeia A is the brightest radio emission source in the night sky above the frequency of 1 Gigahertz. It’s expanding shell of material reaches speeds above 5,000 km/s and temperatures as high as 50 million degrees Fahrenheit. First detected by Martin Ryle and Francis Graham-Smith in 1948, since this time it has become one of the most studied supernova remnants during the human journey to the beginning of space and time.
The startling false-color image above shows the many brilliant, stunning faces of the supernova remnant Cassiopeia A. Composed of images collected by three of the greatest space observatories in history, in three different wavebands of light. This view highlights the beauty hidden within one of the most violent events ever detected close by in the Milky Way.
NASA’s Spitzer Space Telescope infrared images used to create this stunning picture show warm dust in the outer shell of the supernova remnant Cassiopeia A highlighted in red. Hubble Space Telescope images added reveal delicate filaments of hot gas around 10,000 degrees Kelvin (18,000 degrees Fahrenheit) in yellow, while x-ray data collected by NASA’s Chandra X-ray Observatory is shown in green and blue. Look a little closer and deeper at the image and one sees hints of older infrared echoes from after the supernova hundreds of years ago.
Plus nearly a thousand extremely bright, dusty objects nicknamed hot DOGS
Space news (All-sky surveys: infrared; candidate supermassive black holes and dust-obscured galaxies) – The visible universe –
Astronomers working with data provided by an infrared survey of the visible sky conducted by NASA’s Wide-field Infrared Survey Explorer (WISE) have identified millions of new candidates for the quasar section in the Galaxy Zoo. All-sky images taken by WISE revealed around 2.5 million candidate supermassive black holes actively feeding on material, some over 10 billion light-years away. They also pinpointed nearly a 1,000 very bright, extremely dusty objects nicknamed hot DOGS believed to be among the brightest galaxies discovered during the human journey to the beginning of space and time.
“These dusty, cataclysmically forming galaxies are so rare WISE had to scan the entire sky to find them,” said Peter Eisenhardt, lead author of the paper on the first of these bright, dusty galaxies, and project scientist for WISE at JPL. “We are also seeing evidence that these record setters may have formed their black holes before the bulk of their stars. The ‘eggs’ may have come before the ‘chickens.”
“WISE has exposed a menagerie of hidden objects,” said Hashima Hasan, WISE program scientist at NASA Headquarters in Washington. “We’ve found an asteroid dancing ahead of Earth in its orbit, the coldest star-like orbs known and now, supermassive black holes and galaxies hiding behind cloaks of dust.”
Astronomers detected Trojan asteroid TK7 in October 2010 in images of the sky taken by NASA’s WISE, before verifying its existence on optical images taken by the Canada-France-Hawaii Telescope. Additional study and computer modeling indicate Earth’s small dance partner should stay in a safe orbit for the next 10,000 years at least.
In March 2014 astronomers studying infrared images taken by WISE announced the discovery of around 3,500 new stars lying within 500 light-years of Earth. At the same time, they searched the data looking for evidence of Planet X, or Nemesis, the mythical planet some believe to exist somewhere beyond the orbit of Pluto. Scientists analyzed millions of infrared images taken by WISE out to a distance well beyond the orbit of our former ninth planet. They didn’t detect any objects the size of a planet out to a distance of around 25,000 times the distance between the Earth and Sol. Many times beyond the orbit of Pluto. No Planet X was found.
The vast majority of the latest candidates for the Galaxy Zoo are objects previously undetected by astronomers due to dust blocking visible light. Fortunately, the infrared eyes of WISE detected glowing dust around the candidates, which allowed scientists to detect them. These latest findings are clues astronomers use to better understand the processes creating galaxies and the monster black holes residing in their centers.
“We’ve got the black holes cornered,” said Daniel Stern of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., lead author of the WISE black hole study and project scientist for another NASA black-hole mission, the Nuclear Spectroscopic Telescope Array (NuSTAR). “WISE is finding them across the full sky, while NuSTAR is giving us an entirely new look at their high-energy X-ray light and learning what makes them tick.”
Organizing the Monster Zoo
The Monster of the Milky Way, the estimated 4 million solar mass black hole astronomers believe resides at the center, periodically feeds upon material falling too deep into its gravity well, and heats up surrounding disks of dust and gas. Astronomers have even witnessed 1 billion solar mass monster black holes change their surrounding environments enough to shut down star formation processes in their host galaxy. Now, astronomers need to go through the millions of candidates and put them in the correct section of the zoo. We might even need to open a few new sections to accommodate unusual candidates found during a closer examination.
You can learn more about supermassive black holes here.
Hypernova SN 2006gy was over a hundred times brighter than a typical supernova
Space news (astrophysics: hypernovae; one of the brightest ever, SN 2006gy) – 240 million light-years toward the constellation Perseus in galaxy NGC 1260 –
It all started in September of 2006 when a fourth-year University of Texas graduate student astronomer working for the Palomar Transient Factory’s (PTF) luminous supernova program Robert Quimby discovered the brightest celestial event up to this date. An exploding star over 100 times brighter than a normal supernova and shining brighter than the core of its host galaxy NGC 1260.
“This was a truly monstrous explosion, a hundred times more energetic than a typical supernova,” said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas at Austin. “That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We’ve never seen that before.”
Teams of astronomers working with the Katzman Automatic Imaging Telescope at the Lick Observatory on Mt. Hamilton in California and M.W. Keck Observatory near the summit of Mauna Kea on the island of Hawaii immediately began observing the event designated supernova SN 2006gy. Analysis of data showed it occurred over 240 million light-years away in galaxy NGC 1260 and took 70 days to reach maximum brightness. Staying brighter than any previously recorded event for over three months, SN 2006gy was still as bright as a normal supernova eight months later.
“Of all exploding stars ever observed, this was the king,” said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. “We were astonished to see how bright it got, and how long it lasted.”
Astronomers were reasonably sure at this point the progenitor of supernova SN 2006gy was one of the largest, most massive types of stars ever to exist. But they needed to rule out the most likely alternative explanation for the event. The possibility a white dwarf star with a mass slightly higher than Sol went supernova in a dense, hydrogen-rich environment.
Another team of astronomers using the Chandra X-ray Observatory went to work at this point to rule this possibility out of their equations. If this was the case, they knew X-ray emission from the event should be at least 1,000 times more luminous than the readings they were getting.
“This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star,” said Dave Pooley of the University of California at Berkeley, who led the Chandra observations.
The progenitor star for SN 2006gy is thought to have ejected a large volume of mass before the hypernova event occurred. This is similar to events observed by astronomers in the case of Eta Carinae, a nearby supermassive star they’re watching closely for signs of an impending supernova. Only 7,500 light-years toward the constellation Carina, compared to 240 million for galaxy NGC 1260, this star going supernova would be the celestial event of the century on Earth. It would be bright enough to see in the daylight sky.
“We don’t know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case,” said Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research. “Eta Carinae’s explosion could be the best star-show in the history of modern civilization.”
So many questions
Astronomers think in the case of hypernova SN 2006gy things might have taken a slightly different pathway than previously recorded supernovae. Some scientists think the massive star that exploded could be much more like the supermassive stars that existed during the early moments of the cosmos. Supermassive stars that exploded in supernovae and spread the elements of creation across the cosmos, rather than collapsing to a black hole as theorized.
“In terms of the effect on the early universe, there’s a huge difference between these two possibilities,” said Smith. “One [sprinkles] the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole.”
Why would these supermassive stars be different than other huge stars observed in the Milky Way? The human search for answers to these and other mysterious questions before us continues as we journey backward to the beginning of space and time.
We’ll update you with any additional data astronomers come across as the journey continues. Until next time, keep dreaming of the possibilities.
Editor and Chief
The Human Journey to the beginning of space and time.