What Triggers a Type Ia Supernova? Chandra Finds New Evidence

by Nancy Atkinson on April 27, 2011

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This Chandra image of the Tycho supernova remnant contains new evidence for what triggered the original supernova explosion. Credit: NASA/CXC/Chinese Academy of Sciences/F. Lu et al.

What makes a star go boom? A new look at Tycho’s supernova remnant by the Chandra X-ray telescope has supplied astronomers with previously unseen evidence for what could trigger specific type of supernova, a Type Ia supernova explosion. Astronomers have spotted what appears to be material that was blasted off a companion star to a white dwarf when it exploded, creating the supernova seen by Danish astronomer Tycho Brahe in 1572. There is also evidence that this material blocked the explosion debris, creating an “arc” and a “shadow” in the supernova remnant.

There are two main types of supernovae. One is where a massive star – much bigger than our sun — burns all its nuclear fuel and collapses in on itself, which ignites a supernova explosion. Type Ia supernovae, however, are different. Smaller stars eventually turn into white dwarfs at the end of their lives, becoming an ultra-dense ball of carbon and oxygen about the size of the Earth, with the mass of our Sun. In some instances, though, a white dwarf somehow ignites, creating an explosion so bright that it can be seen billions of light years away, across much of the Universe. But astronomers really haven’t understood what causes these explosions to start.

There are a couple of popular theories: one scenario for Type Ia supernovas involves the merger of two white dwarfs. In this case, no companion star or evidence for material blasted off a companion should exist. In the other theory, a white dwarf pulls material from a “normal,” or Sun-like, companion star until a thermonuclear explosion occurs.

Both scenarios may actually occur under different conditions, but the latest Chandra result from Tycho supports the latter one.

This is an artist's impression showing an explanation from scientists for the origin of an X-ray arc in Tycho's supernova remnant. Credit: NASA/CXC/M.Weiss

The new Chandra images show the famous leftovers of Tycho’s supernova, and reveal for the first time an arc of X-ray emission within the supernova remnant. The shape of the arc is different from any other feature seen in the remnant. This supports the conclusion that a shock wave created the arc when a white dwarf exploded and blew material off the surface of a nearby companion star.

In addition, this new study seems to show how resilient some stars can be, as the supernova explosion appears to have blasted very little material off the companion star. Previously, studies with optical telescopes have revealed a star within the remnant that is moving much more quickly than its neighbors, hinting that it could be the missing companion.

“It looks like this companion star was right next to an extremely powerful explosion and it survived relatively unscathed,” said Q. Daniel Wang of the University of Massachusetts in Amherst, a member of the research team whose paper will appear in the May 1st issue of The Astrophysical Journal. “Presumably it was also given a kick when the explosion occurred. Together with the orbital velocity, this kick makes the companion now travel rapidly across space.”

This image shows iron debris in Tycho's supernova remnant. The site of the supernova explosion is shown, as inferred from the motion of the possible companion to the exploded white dwarf. The position of material stripped off the companion star by the explosion, and forming an X-ray arc, is shown by the white dotted line. This structure is most easily seen in an image showing X-rays from the arc's shock wave. Finally, the arc has blocked debris from the explosion creating a "shadow" in the debris between the red dotted lines, extending from the arc to the edge of the remnant. Credit: NASA/CXC/Chinese Academy of Sciences/F. Lu et al.

Using the properties of the X-ray arc and the candidate stellar companion, the team determined the orbital period and separation between the two stars in the binary system before the explosion. The period was estimated to be about 5 days, and the separation was only about a millionth of a light-year, or less than a tenth the distance between the Sun and the Earth. In comparison, the remnant itself is about 20 light-years across.

Other details of the arc support the idea that it was blasted away from the companion star. For example, the X-ray emission of the remnant shows an apparent “shadow” next to the arc, consistent with the blocking of debris from the explosion by the expanding cone of material stripped from the companion.

“This stripped stellar material was the missing piece of the puzzle for arguing that Tycho’s supernova was triggered in a binary with a normal stellar companion,” said Fangjun Lu of the Institute of High Energy Physics, Chinese Academy of Sciences in Beijing. “We now seem to have found this piece.”

Because Type Ia supernova are all of similar brightness, they are used as a standard candle to measure the expansion of the Universe, and this new observation by Chandra has helped to answer at least part of the long-standing – and critical — question of what triggers these bright explosions.

Source: Chandra


Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

SteveZodiac April 27, 2011 at 10:42 AM

I wonder if it’s possible to find any evidence of “super-soft” x-rays from the accretion prior to exceeding the Chandrasekhar limit? I would expect it to be 439 years too late but maybe someone has a clever technique..

Feenixx April 27, 2011 at 11:35 AM

Apart from new scientific insights it provides… I find this one of the most amazing looking evocative images you ever published. I can almost see it animated, with those debris clouds billowing and bulging. What a cool on-stage projection for some kind of a show this would make!

FVRBLACKTYGER April 27, 2011 at 12:20 PM

System stars are compatible and like a battery are rechargeable with the correct plama. Might have to be sent a few million light years. System stars do not supply plasma to non compatible stars,and such stars are likely to explode or collapse. The comparison is like a recargeable battery and a non rechargeable one. Like a light bulb. Connect to the wrong supply (as with Star Plasma) and the bulb blows.
Plasma from a Blue white in M 51 Galaxy can be input to M 31 as both are in system.
It is my undestanding that this local star is IN SYSTEM,although currently at POWER LOCK OUT, subject to restricted Protocols.
Stars also collapse when the SYSTEM STARS instruct removal of their star plama. This can cause the polar and anti polar ice sheets to move substantially and suddenly at a Footstool. Removal of Star plasma, particualry from a Footstool, will be seen by the Volcanic eruptions venting star plasma. Volcano names will usually specify the Galaxy removing ( or adding Star Plasma). Thus GRMS FVOTTYEN for Iceland and M 51. Star plasma may need to be added to reposition the Footstool.
Footstool is the technical name where the Star and its Footstool are IN SYSTEM.

Torbjorn Larsson OM April 27, 2011 at 3:22 PM

No. Read again, it is mass that triggers these episodes, not dependent on plasma “type” (degree of ionization?). We can’t speculate without data, but we can reject erroneous theories non-compatible with it. This is one of them.

FVRBLACKTYGER April 28, 2011 at 9:40 AM

Mass in my lug? We were over that in the 1600′s. The photograph is of what is a Blue Black Star. Hots coals is also a reference for this type of Star depending on the level of Understanding. The blue ring is of the Blue and Blue White Star plasma which has variable mass, occasionally NO mass! It is about the size of a pinhead,and is VERY illusive. Now you see it, now you do not. You may seek it here, or there but will not find it in particle accelerators. They simply demonstrate wrong undestanding. If the best you can do is to smash Atoms and look for yet smaller fragments, then the Star Plasma will simply move away. That is what causes stars to collapse,since essentially they are containers for the Hot Star Plasma.

This local star may look like a white dwarf, but as a system star, it has a very substantial defense mechanism, which some have called the divine wind! It also has very powerful friends in its system stars, which are often referred to as Dragons! Blue, White, and Black Dragons! That is also a reference for Galaxies; if you want to talk Dragon Speak.

The most recent Whapp, was off Nypon! I am not speculating. Factual from my point of view, and seriously checked by the local System Fire Disc!

Blue and Blue white Star Plasma is saferly sent instantly over millions of light years on NO mass basis. Footstool is the technical description when the local Star and its Galaxy are in System. System Galaxy references KGC 31, KGC 51, and KGC 1300, KGC 1365. KGC 107 is this Galaxy.

I assess the current weight of this Galaxy on a Syatem Galaxy basis as 22 grams in containers and 11 grams without! AU at 1 and 1/2 sovereign! That is technical. The Footstool weighting is at 3d, but Barred Spiral and Syfert Sculptor System! That means that there is very limited scientific undestanding of the real Galactic Science,and disappointment that there has been no real progress since the 1600′s!

There is plenty in this text for the local population to work with! The Footstool repostion is still necessary, and is instructed. KGC 1365.

tacitus April 28, 2011 at 4:36 PM

Is this a joke?

Olaf April 27, 2011 at 10:41 PM

Star Plasma? Volcanic Eruptions? None compatible stars? Light bulbs?

So Volcanoes are the evil ones triggered by someone that replaced the wrong light-bulb.

Torbjorn Larsson OM April 27, 2011 at 3:19 PM

+1 on the images! Amazing what new observatories can come up with.

FleetFoot April 27, 2011 at 10:46 PM

The shadow effect is even clearer in the high energy x-ray image:


There could even be evidence for shadow of a “hot Jupiter” companion about 5 o’clock on the edge of the companion star shadow.

Does anyone know why there seems to be a double layer on the left hemisphere?

Torbjorn Larsson OM April 28, 2011 at 7:44 AM

To me it looks like the perspective of an uneven expansion: the outlines aren’t exact copies. And there are two similar outlines on the right hs, and one each top/bottom.

FleetFoot April 28, 2011 at 11:24 AM

I’m wondering if it might be a result of an off-centre initiation:


The layers might the material ejected directly from the outer layer above the initiation point versus that from the deeper core material ejected after the reaction had first gone inwards.

An alternative might be the direct shock wave from the initiation point versus one reflected from a deeper layer.

The above is purely speculation of course, just musing on possibilities over lunch.

Lawrence B. Crowell April 28, 2011 at 11:59 AM

This data is good news. This gives support for the hypothesis or theory that SNIa are due to dwarf stars which increase their mass beyond their Chandrasekhar limit and implode to generate a stellar mass hydrogen bomb. The white dwarf increases it mass by siphoning off mass from a companion star that is close enough so the Roche lobe crosses a Lagrange point. The white dwarf star increases it mass to 1.3M_{sol} and the cosmic H-bomb is lit. This means the luminosity of these objects is well calibrated and can be used as a cosmic standard candle. So this evidence is good news.

The other features were discussed here at UT a couple of months ago. These are, as I recall, due to charged particles spiraling around magnetic fields that generate X-rays by Bremsstrahlung radiation process.


Jon Hanford April 28, 2011 at 12:11 PM

In 2008 the 8.2m Subaru telescope obtained spectra of the Tycho supernova near maximum brightness, by observing a light echo of the supernova 436 years after the event: http://arxiv.org/ftp/arxiv/papers/0810/0810.5106.pdf

These observations lent support to the accreting white dwarf scenario and confirmed the supernova was a normal Type Ia SN.

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