Starship Asterisk*

Ann wrote:Adam's picture shows that there is a lot of dust where the supernova is located, which explains its reddish color.

BDanielMayfield wrote:Since it is expected to brighten for another two weeks, and since a supernova can breifly out-shine an entire galaxy, how bright can we expect this to become? Will this become a naked eye object?

TimJewell wrote:If a star with sufficient mass near our solar system were to supernova, what would that mean for us on Earth? Would it appear as bright as our sun? Is there a danger that the blast would be so great it would rip the atmosphere from our planet?

Nitpicker wrote:

TimJewell wrote:
If a star with sufficient mass near our solar system were to supernova, what would that mean for us on Earth? Would it appear as bright as our sun? Is there a danger that the blast would be so great it would rip the atmosphere from our planet?

It depends how near you mean.

The Sun has an apparent magnitude of -26.7. The next nearest star is about four light years from us. If a Normal Type Ia supernova happened at that distance from us, it would shine with an apparent magnitude of about -24 [sums unchecked], so not quite as bright as the Sun from our perspective. I'm not sure, but I reckon we might be in a spot of radioactive bother, if such a supernova happened so close.

http://en.wikipedia.org/wiki/Near-Earth_supernova wrote:
<<Adrian L. Melott et al. estimated that gamma ray bursts from "dangerously close" supernova explosions occur two or more times per billion years, and this has been proposed as the cause of the end Ordovician extinction, which resulted in the death of nearly 60% of the oceanic life on Earth.>>

http://en.wikipedia.org/wiki/Near-Earth_supernova wrote:
<<A near-Earth supernova is an explosion resulting from the death of a star that occurs close enough to the Earth to have noticeable effects on its biosphere.

On average, a supernova explosion occurs within 10 parsecs (33 light-years) of the Earth every 240 million years. Gamma rays are responsible for most of the adverse effects a supernova can have on a living terrestrial planet. In Earth's case, gamma rays induce a chemical reaction in the upper atmosphere, converting molecular nitrogen into nitrogen oxides, depleting the ozone layer enough to expose the surface to harmful solar and cosmic radiation. Phytoplankton and reef communities would be particularly affected, which could severely deplete the base of the marine food chain.

Speculation as to the effects of a nearby supernova on Earth often focuses on large stars as Type II supernova candidates. Several prominent stars within a few hundred light years from the Sun are candidates for becoming supernovae in as little as a millennium. One example is Betelgeuse, a red supergiant about 640 light-years from Earth. Though spectacular, these "predictable" supernovae are thought to have little potential to affect Earth.

Recent estimates predict that a Type II supernova would have to be closer than eight parsecs (26 light-years) to destroy half of the Earth's ozone layer. Such estimates are mostly concerned with atmospheric modeling and considered only the known radiation flux from SN 1987A, a Type II supernova in the Large Magellanic Cloud. Estimates of the rate of supernova occurrence within 10 parsecs of the Earth vary from 0.05-0.5 per Ga to 10 per Ga. Several authors have based their estimates on the idea that supernovae are concentrated in the spiral arms of the galaxy, and that supernova explosions near the Sun usually occur during the ~10 million years that the Sun takes to pass through one of these regions (we are now in or entering the Orion arm). The relatively recent paper by Gehrels et al. uses a value of 3 supernovae less than 10 parsecs away per Ga. The frequency within a distance D is proportional to D3 for small values of D, but for larger values is proportional to D2 because of the finite thickness of the galactic disk (at intergalactic distances D3 is again appropriate). Examples of relatively near supernovae are the Vela Supernova Remnant (~800 ly, ~12,000 years ago) and Geminga (~550 ly, ~300,000 years ago).

Type Ia supernovae 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 10 parsecs (33 light-years) to affect the Earth. The closest known candidate is IK Pegasi. It is currently estimated, however, that by the time it could become a threat, its velocity in relation to the Solar System would have carried IK Pegasi to a safe distance.

Evidence from daughter products of short-lived radioactive isotopes shows that a nearby supernova helped determine the composition of the Solar System 4.5 billion years ago, and may even have triggered the formation of this system. Supernova production of heavy elements over astronomic periods of time ultimately made the chemistry of life on Earth possible.

In 1996, astronomers at the University of Illinois at Urbana-Champaign theorized that traces of past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata. Subsequently, iron-60 enrichment has been reported in deep-sea rock of the Pacific Ocean by researchers from the Technical University of Munich. 23 atoms of this iron isotope were found in the top 2 cm of crust, and these date from the last 13 million years or so. It is estimated that the supernova must have occurred in the last 5 million years or else it would have had to have happened very close to the solar system to account for so much iron-60 still being here. A supernova occurring so close would have probably caused a mass extinction, which didn't happen in that time frame. The quantity of iron seems to indicate that the supernova was less than 30 parsecs away. On the other hand, the authors estimate the frequency of supernovae at a distance less than D (for reasonably small D) as around (D/10 pc)3 per Ga, which gives a probability of only around 5% for a supernova within 30 pc in the last 5 million years. They point out that the probability may be higher because we are entering the Orion arm of the Milky Way.

In 2009, researchers have found nitrates in ice cores from Antarctica at depths corresponding to the known supernovae of 1006 and 1054 CE, as well as from around 1060 CE. The nitrates were apparently formed from nitrogen oxides created by gamma rays from the supernovae. This technique should be able to detect supernovae going back several thousand years.

In 1998 a supernova remnant, RX J0852.0-4622, was found in front (apparently) of the larger Vela Supernova Remnant. Gamma rays from the decay of titanium-44 (half-life about 60 years) were independently discovered coming from it, showing that it must have exploded fairly recently (perhaps around 1200 CE), but there is no historical record of it. The flux of gamma rays and x-rays indicates that the supernova was relatively close to us (perhaps 200 parsecs or 660 ly). If so, this is a surprising event because supernovae less than 200 parsecs away are estimated to occur less than once per 100,000 years.>>

Ann wrote:
Oh, what a timely APOD! And I'm so glad that Adam Block's superb image was the one chosen to show this new supernova.

Adam's picture shows that there is a lot of dust where the supernova is located, which explains its reddish color. In any case, it is going to be so interesting to see how this supernova evolves!

Ironwood wrote:
It looks to me as if the arrow is misaligned. The bright structure it points toward looks to be a cloud thousands of light years in diameter rather than a point source new supernova.

neufer wrote:

Ann wrote:
Oh, what a timely APOD! And I'm so glad that Adam Block's superb image was the one chosen to show this new supernova.

Adam's picture shows that there is a lot of dust where the supernova is located, which explains its reddish color. In any case, it is going to be so interesting to see how this supernova evolves!

OTOH...in order to bring out that dust in the picture every point source over 14th magnitude is overexposed and we have little real sense as to the actual brightness of the supernova.

Ironwood wrote:
It looks to me as if the arrow is misaligned. The bright structure it points toward looks to be a cloud thousands of light years in diameter rather than a point source new supernova.

The arrow is slightly misaligned but the large bright structure it (almost) points towards is the overexposed supernova.

Angelino1984 wrote:Nice Pic,how far is M82?

rstevenson wrote:

Angelino1984 wrote:Nice Pic,how far is M82?

As it says under the pic, "M82 is a mere 12 million light-years away".

Perhaps you read that and didn't recognize it as a distance. One light-year is the distance covered by light in one year -- and light travels at 300,000 km/s. So the light from M82 has been travelling towards us for 12 million years, at its usual pace of 300,000 km/s. That puts M82 a long way away!

Chris Peterson wrote:

rstevenson wrote:

Angelino1984 wrote:Nice Pic,how far is M82?

As it says under the pic, "M82 is a mere 12 million light-years away".

Perhaps you read that and didn't recognize it as a distance. One light-year is the distance covered by light in one year -- and light travels at 300,000 km/s. So the light from M82 has been travelling towards us for 12 million years, at its usual pace of 300,000 km/s. That puts M82 a long way away!

I'd say it makes it one of the very closest galaxies we see. Indeed, only an infinitesimal fraction of all we observe in the Universe is closer to us than a mere 12 million light years.

Nitpicker wrote:On the other hand, the vast majority of apparently bright objects we see in the night sky (with just our eyes, binoculars, or a small telescope) are within the Milky Way, more than 100 times closer than M82.

Chris Peterson wrote:

rstevenson wrote:... That puts M82 a long way away!

I'd say it makes it one of the very closest galaxies we see. Indeed, only an infinitesimal fraction of all we observe in the Universe is closer to us than a mere 12 million light years.

rstevenson wrote:It's all relative, as you know.

If we take the fastest launch speed we've ever achieved, that of New Horizons (according to this Scientific American blog), 45 km/s, then our travel time (assuming we could maintain that speed, which we can't, because of the Sun's gravity) would be 300000/45 x 12 million, or about 8 billion years. In my book, that's a long way away, even if almost everything else is even farther away.