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T Pyxidis potential near supernova?


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T Pyxidis, estimated 3000 lightyears from us, is being presented in science media as a potential supernova.


I'm not sure this is right, or that it will be confirmed. But I respect Steinn Sigurdsson. He's a reputable astrophysicist. In my opinion reliable and hardhead, not a speculator. Judge for yourself from his other blog posting. Here's what he says about the T Pyxidis news:



The reports come from a group at Villanova University led by Prof. Edward Sion. What I get from this is that T Pyxidis is extremely interesting but most likely far enough away not to pose a threat to Earth, although this remains to be confirmed. And in any case I do not see how the data imply the possibility that the star will go supernova.


The explosion they think T Pyxidis is preparing for for is type Ia. It is especially important to improve our understanding of the mechanism of type Ia supernova explosions because they are used as a standard candle in establishing distances in cosmology. From Sigurdsson's post I get the impression that although much is known about type Ia, from hundreds of observations, still the mechanism that causes them is imperfectly understood.



Here's something from the media:



Wikipedia authors seem to think the star could present some hazard:



The star has recurrently gone nova. Flareups have been recorded in 1890, 1902, 1920, 1944 and 1966 (or 1967), but not since then. The increasing interval suggests to me that the star is actually losing mass, because it takes progressively more build up on the surface in order for a nova flash to happen.

Edited by Martin
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Wow, that would really be something. Has there ever even been one that close in recorded history?


If it actually did happen, it would be an amazing sight. Personally I never heard of anything like that happening in recorded history. Novas are fairly common, but supernovas are rare---I don't recall how rare they are estimated to be. Maybe you know.


Hopefully we'll hear some more about this. Chance to pick up information.


With core-collapse SNe, like type Ib, or II, the SN leaves a remnant, like a neutron star. But did you know that with type Ia it is different? Apparently there is no remnant left after the explosion.


With type Ia it is a modest-size star that is not massive enough to do any more fusion----so after a while fusion stops with elements like Oxygen. But the star is gradually accreting material from a binary partner. And it gradually builds up to the critical mass of 1.4 solar. And then the whole thing goes, by abrupt nuclear fusion, leaving no remnant. Think of it as an "oxygen bomb" analogous to a hydrogen bomb----powered by fusion rather than by collapse.


At least I think so, haven't checked. Maybe you can confirm. More usual SNe are powered by the sudden collapse, releasing gravitational energy, and the resulting rebound shock. So its really different.

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Just going by Wikipedia, it looks like there have been about a dozen supernovae visible to the naked eye, although only five have actually been confirmed by identifying the predicted remnants. The earliest was in 185AD, and the most recent was in 1604. Kepler wrote a book about it. The one in 185 would have been only about 3000ly away, and there is one claimed remnant only about 700ly away, although it should have been visible from Earth around 1250AD, and there are no records of it. The others are all farther.


So yeah, it would be a rare and amazing event.

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