Caught in the act: Astronomers find a rare supernova 'impostor' in a nearby galaxy

February 12, 2016 by James Urton, University of Washington
An image obtained by UW astronomer Breanna Binder's group using the Hubble Space Telescope, showing the supernova impostor SN 2010da circled in green and the X-ray emission indicated by a white cross. Reproduced from a Royal Astronomical Society publication: MNRAS (April 01, 2016) 457 (2): 1636-1643.doi: 10.1093/mnras/stw119 Credit: Royal Astronomical Sociey, Breanna Binder, NASA

Breanna Binder, a University of Washington postdoctoral researcher in the Department of Astronomy and lecturer in the School of STEM at UW Bothell, spends her days pondering X-rays.

As she and her colleagues report in a new paper published Feb. 12, 2016 in the Monthly Notices of the Royal Astronomical Society, they recently solved a mystery involving X-rays—a case of X-rays present when they shouldn't have been. This mystery's unusual main character—a star that is pretending to be a —illustrates the importance of being in the right place at the right time.

Such was the case in May 2010 when an amateur South African astronomer pointed his telescope toward NGC300, a nearby galaxy. He discovered what appeared to be a supernova—a massive star ending its life in a blaze of glory.

"Most supernovae are visible for a short time and then—over a matter of weeks—fade from view," said Binder.

After a star explodes as a supernova, it usually leaves behind either a black hole or what's called a neutron star—the collapsed, high-density core of the former star. Neither should be visible to Earth after a few weeks. But this supernova—SN 2010da—still was.

"SN 2010da is what we call a 'supernova impostor'—something initially thought to be a supernova based on a bright emission of light, but later to be shown as a massive star that for some reason is showing this enormous flare of activity," said Binder.

The galaxy NGC 300, home to the unusual system Binder and her colleagues studied. The spiral galaxy is over 6 million light years away. Credit: NASA/JPL-Caltech/OCIW

Many supernova impostors appear to be in a binary system—two in orbit of one another. Stellar astrophysicists think that the impostor's occasional flare-ups might be due to perturbations from its neighbor.

For SN 2010da, the story appeared to be over until September 2010—four months after it was confirmed as an impostor—when Binder pointed NASA's Chandra X-ray Observatory toward NGC300 and found something unexpected.

"There was just this massive amount of X-rays coming from SN 2010da, which you should not see coming from a supernova impostor," she said.

Binder considered a variety of explanations. For example, material from the star's corona could be hitting a nearby dust cloud. But that would not produce the level of X-rays she had observed. Instead, the intensity of the X-rays coming from SN 2010da were consistent with a neutron star—the dense, collapsed core remnant of a supernovae.

"A neutron star at this location would be surprising," said Binder, "since we already knew that this star was a supernova impostor—not an actual supernova."

In 2014, Binder and her colleagues looked at this system again with Chandra and, for the first time, the Hubble Space Telescope. They found the impostor star and those puzzling X-ray emissions. Based on these new data, they concluded that, like many other supernovae impostors, SN 2010da likely has a companion. But, unlike any other supernovae impostor binary reported to date, SN 2010da is probably paired with a neutron star.

"If this star's companion truly is a neutron star, that would mean that the neutron star was once a giant, massive star that underwent its own supernova explosion in the past," said Binder. "The fact that this supernova event didn't expel the other star, which is 20 to 25 times the mass of our sun, makes this an incredibly rare type of binary system."

To understand how this unusual binary system could form, Binder and her colleagues considered the age of the stars in this region of space. Looking at stellar size and luminosity, they discovered that most nearby stars were created in two bursts—one 30 million years ago and the other less than 5 million years ago. But neither SN 2010da nor its presumed neutron star companion could've been created in the older burst of starbirth.

"Most stars that are as massive as these usually live 10 to 20 million years, not 30 million," said Binder. "The most massive, hottest stars can form, grow, swell, explode and leave a neutron star emitting X-rays in about 5 million years."

Surveys of the galaxy as recently as 2007 and 2008 detected no X-ray emissions from the location of SN 2010da. Instead, Binder believes that the X-rays they first found in 2010 represent the neutron star "turning on" for the first time after its formation. The X-rays are likely produced when material from the impostor star is transferred to the neutron star companion.

"That would mean that this is a really rare system at an early stage of formation," said Binder, "and we could learn a lot about how massive stars form and die by continuing to study this unique pairing."

One mystery solved, Binder would like to keep looking at SN 2010da, seeing what else she can learn about its formation and evolution. Its home galaxy, which has yielded unique pairings previously, is sure to keep her busy. She is also planning a follow-up study of other recent supernova impostors with the help of an undergraduate research assistant at UW Bothell.

Explore further: Image: Hubble checks out a home for old stars

More information: B. Binder et al. Recurring X-ray outbursts in the supernova impostor SN 2010da in NGC 300, Monthly Notices of the Royal Astronomical Society (2016). DOI: 10.1093/mnras/stw119

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1.9 / 5 (9) Feb 12, 2016
When all you have is a hammer (gravity), every problem is a nail (mass). So that's the only way X-rays are generated? Neutron star matter has never been created in a lab, but plasma double layers emitting enormous amounts of X-rays are easily recreated in labs.
2.6 / 5 (5) Feb 13, 2016

"In conclusion, it seems that astrophysics is too important to be left in the hands of theoretical astrophysicists who have gotten their education from the listed textbooks. The multibillion dollar space data from astronomical telescopes should be treated by scientists who are familiar with laboratory and magnetospheric physics, circuit theory, and, of course, modern plasma physics. More than 99 percent of the Universe consists of plasma, and the ratio between electromagnetic and gravitational forces is 10^39."

— Hans Alfvén, his final words in his Noble prize acceptance speech.

Captain Stumpy
3.3 / 5 (7) Feb 13, 2016
Hans Alfvén, his final words in his Noble prize acceptance speech
@old C
are you making an assumption about the abilities of the astrophysicists of today?

that is a tired old (and repeatedly debunked) argument of the electric universe acolytes like cantdrive... and it is not only false, but based upon a blatant lie and continually promoted as factual regardless of the wealth of information that proves it wrong
(See also: for more information)

also note, astrophysics is NOT "left in the hands of theoretical astrophysicists"... this is another blatant lie propagated by the eu for self-serving purposes

i suggest checking into higher education curriculum for more information before accepting a seriously flawed old quote that is not applicable regardless of the credentials of the author of said quote
3 / 5 (4) Feb 14, 2016
I think you refer to Perrat quoting Alfvén in his 1988 book:

Students using astrophysical textbooks remain essentially ignorant of even the existence of plasma concepts, despite the fact that some of them have been known for half a century. The conclusion is that astrophysics is too important to be left in the hands of astrophysicists who have gotten their main knowledge from these textbooks. Earthbound and space telescope data must be treated by scientists who are familiar with laboratory and magnetospheric physics and circuit theory, and of course with modern plasma theory.

Hans Alfvén, as quoted by Anthony Perrat in his 1988 book.

Here's another, as you defend the gravity priests collection plate daily:

Scientists tend to resist interdisciplinary inquiries into their own territory. In many instances, such parochialism is founded on the fear that intrusion from other disciplines would compete unfairly for limited financial resources
3 / 5 (4) Feb 14, 2016
FYI: EU is largely promoting Talbott's concepts of catastrophism by mythological accounts and has no sensible timeline or orbital mechanics to allow such bizarre sky displays.

The Plasma Cosmology concepts IEEE are promoting is not related to EU.
Captain Stumpy
3 / 5 (6) Feb 14, 2016
I think you refer to...
no, i was referring to your post and inferences WRT modern astrophysics, which mimic the eu claims (which are not only debunked, but have been for decades)

there is "some" merit to plasma cosmology, but when you ignore evidence for the sake of a personal belief in something (which is prevalent in a lot of plasma cosmology posters here on PO) then you are ignoring the science

also note: IEEE is a predominantly engineering journal without adequate astrophysical peer for review of astrophysical phenomenon

as i stated before: astrophysicists learn plasma physics, but engineer's do NOT learn astrophysics
See MIT link above for validation of this
if you were to link PPPL or another shared lab (between astro's and engineers) it would be a far cry better than IEEE linked for astrophysics
4.2 / 5 (5) Feb 14, 2016
By using the term "gravity priests" you create the suspicion that you have no arguments.
If you had you would present them instead.
Your quote from Afvén is passive aggressive. Using it will only damage Alfvén's reputation.
2.3 / 5 (3) Feb 16, 2016
FYI: EU is largely promoting Talbott's concepts of catastrophism by mythological accounts and has no sensible timeline or orbital mechanics to allow such bizarre sky displays.

The Plasma Cosmology concepts IEEE are promoting is not related to EU.

That doesn't matter to Stumpid. You disagree with him, thus you will find yourself in endless post wars with someone who knows jack about science and will only wind up making idiotic evaluations of you and your science understanding, coupled with mass appeals to the authorities he does believe in.

Put him on ignore, remove him from that status once every couple of days to rate all of his posts a 1 ( he jerks off to 5's) then back on's all he deserves.
Captain Stumpy
4 / 5 (4) Feb 18, 2016
someone who knows jack about science
you mean your comments are all about science and evidence? like this?
My comments reflect doubt in the face of questionable reporting
no evidence supporting your conclusions- IOW, a false claim

Amazing that with all the tech on earth and in orbit MORE sensitive to motion than LIGO, it was the only thing to react...
untested claim
If you think a system such as this: would be immune to an effect that LIGO could detect, I would steer clear of won't be very good at it
false claim & ignorance
The standard model is wrought with holes and contradictions
false claim
the fact that I doubt most mainstream theories
this means you don't understand the evidence

yet i am the one who "knows jack about science"?

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