Astronomers Awaiting 1a Supernova

Aryabhata writes to tell us BBC News is reporting that astronomers have sighted a star on the brink of a "1a" supernova. This opportunity presents the first chance astronomers have ever had to view a supernova of this magnitude up close. From the article: "They are so rare that the last one known in our galaxy was seen in 1572 by the great Danish astronomer Tycho Brahe, who first coined the term nova, for "new star", not realizing he was in fact witnessing the violent end of an unknown star. It has long been believed that type 1a supernovae are the death throes of a white dwarf star. But all modern ones have been so distant that it has not been possible to see what had been there beforehand."

Comments

Actually

[ArchieBunker]

It happened long ago and the light is just now reaching us.

The star is 1,950 light years away?

[Mantrid42]

http://en.wikipedia.org/wiki/Supernova#Impact_of_s upernovae_on_Earth

Speculation as to the effects of a nearby supernova on Earth often focuses on large stars, such as Betelgeuse, a red supergiant 427 light years from Earth which is a type II supernova candidate. Several prominent stars within a few hundred light years from the Sun are candidates for becoming supernovae in as little as 1000 years. Though spectacular, these "predictable" supernovae are thought to have little potential to affect Earth. Type Ia supernovae, though, are thought to be potentially the most dangerous if they occur close enough to the Earth. Because Type Ia supernovae arise from dim, common white dwarf stars, it is likely that a supernova that could affect the Earth will occur unpredictably and take place in a star system that is not well studied. One theory suggests that a Type Ia supernova would have to be closer than 1000 parsecs (3300 light years) to affect the Earth.

Shit.

Re:The star is 1,950 light years away?

[KylePetty]

Before everyone goes nuts saying our goose is cooked. It appears that not all sources agree as to the distance of this star. While some sources claim the star is 1,950 light years away, others claim it is as much as 5,000 light years away. http://www.sciencenews.org/articles/20060722/fob8. asp On referring to RS Ophiuchi, ScienceNews states: "That finding could have two interpretations, suggests the report's coauthor Richard Barry of NASA's Goddard Space Flight Center in Greenbelt, Md. If the star system resides at about 5,000 light-years from Earth, then the emissions reflect a mysterious, dense reservoir of material surrounding the two stars. If the system lies at only about one-third that distance, then the emission may for the first time be revealing a short-lived epoch during which the white dwarf, soon after its outburst, becomes as bloated as its red giant partner." Sites like Space.com claim it is 5,000 light years away, while Wiki has it pegged at 1,950. Meanwhile, the Harvard Gazette reports that: "When do scientists think the Ophiuchi supernova will rock the universe? Of course, no one knows enough about what goes on out there to say. But the best guess is it will take thousands of years for the final bit of gas to accumulate and blow the white dwarf away. Meanwhile, these reports should stimulate many more astronomers to focus their attention on the constellation Ophiuchi." So... I think it's a bit premature to claim we are doomed.

Range of lethality

[Short Circuit]

I'm curious. At what range would a Type 1a supernova be lethal to life on Earth?

As far as the size of the galaxy is concerned, 1,950 light-years is essentially in our back-yard. Keeping with scale, are we talking about a firecracker or a stick of dynamite?