Supernova to be visible for 2 nights

David Perlman, SF Chronicle Science Editor
Thursday, September 8, 2011

A dying star that exploded 21 million years ago in a cataclysmic burst of energy called a supernova has sent its light streaming across the cosmos, leaving a pinpoint of light in the sky that Bay Area residents with a good pair of binoculars should be able to see over the next two nights.

The supernova, brighter than all the stars in the universe combined, blazed from a galaxy near the constellation Big Dipper, according to Peter Nugent, an astronomer and senior scientist at the Lawrence Berkeley National Laboratory who detected its light last week.

Despite its explosive brilliance, the light is dim at this distance. Its faint light will reach its peak tonight and Friday night, and should be visible in the clear night sky through a quality pair of binoculars or with amateur telescopes of 3 inches or larger, Nugent said.

He picked up the supernova soon after the explosion became visible on Aug. 23 in an image sent from an automated telescope at the famed Palomar Observatory near San Diego. Astronomers haven't seen a supernova so close to Earth in 25 years, he said - nor one as bright in more than 40 years.

While the explosion was immense, it involved a star of only modest dimensions - a white dwarf only 1.4 times the mass of our sun, Nugent said.

Supernovas are common, but most are more than a billion light-years away and are too faint to be visible except through the most powerful telescopes. So the opportunity to observe one only 21 million light-years away has astronomers aiming their telescopes at the blast from observatories around the world.

The Hubble Space Telescope has also been assigned to begin studying the physics and chemistry of the explosion, NASA officials said.

This supernova is classed as Type 1a, and is catalogued under the name PTF11kly. The exploding star was one member of a stellar pair, known as a binary system, that had already burned away its hydrogen and helium in thermonuclear explosions, leaving only its carbon and oxygen to fuel the final outburst, Nugent said.

Because the light intensity of supernovas is well known, astronomers use them as "standard candles" to calculate the distances of far-off galaxies, and thus measure the rate at which the entire universe is expanding under the mysterious influence of what is called dark energy, Nugent explained.

Alex Filippenko, leader of a team of supernova observers at the UC Lick Observatory, said this newest one will prove valuable in helping astronomers to refine their distance calculations for those standard candles.

It should also shed new light on the exploding star's companion, Filippenko said. For example, astronomers might be able to determine whether the binary pair were both originally white dwarf stars, and whether the star that exploded might have been "stealing matter from its companion" as it built up toward its final blast, or - perhaps - whether both stars merged to explode in a single blast.

Every explosion of a supernova sends out bursts of all the elements that make up every bit of matter in the universe. "All the calcium in our bones, all the iron in our blood, all the chemicals in our bodies, came originally from supernovas that exploded even before the Earth was formed," Nugent said.

How to see it

Berkeley astronomer Peter Nugent explains how to see the supernova on You Tube: sfgate.com/ZLCS.

Learning more

Free talk on the supernova by Berkeley astronomer Peter Nugent.

Where: Chabot Space and Science Center, 10000 Skyline Blvd., Oakland.

When: Beginning at dusk Saturday as the center's telescopes focus on the Pinwheel Galaxy, where the cosmic explosion's light is visible.

E-mail David Perlman at dperlman@sfchronicle.com.



Read more: http://www.sfgate.com/cgi-bin/article ... K1L0P5I.DTL#ixzz1XNWcVlJE

Supernova to be visible for 2 nights

David Perlman, SF Chronicle Science Editor
Thursday, September 8, 2011

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A dying star that exploded 21 million years ago in a cataclysmic burst of energy called a supernova has sent its light streaming across the cosmos, leaving a pinpoint of light in the sky that Bay Area residents with a good pair of binoculars should be able to see over the next two nights.

The supernova, brighter than all the stars in the universe combined, blazed from a galaxy near the constellation Big Dipper, according to Peter Nugent, an astronomer and senior scientist at the Lawrence Berkeley National Laboratory who detected its light last week.

Despite its explosive brilliance, the light is dim at this distance. Its faint light will reach its peak tonight and Friday night, and should be visible in the clear night sky through a quality pair of binoculars or with amateur telescopes of 3 inches or larger, Nugent said.

He picked up the supernova soon after the explosion became visible on Aug. 23 in an image sent from an automated telescope at the famed Palomar Observatory near San Diego. Astronomers haven't seen a supernova so close to Earth in 25 years, he said - nor one as bright in more than 40 years.

While the explosion was immense, it involved a star of only modest dimensions - a white dwarf only 1.4 times the mass of our sun, Nugent said.

Supernovas are common, but most are more than a billion light-years away and are too faint to be visible except through the most powerful telescopes. So the opportunity to observe one only 21 million light-years away has astronomers aiming their telescopes at the blast from observatories around the world.

The Hubble Space Telescope has also been assigned to begin studying the physics and chemistry of the explosion, NASA officials said.

This supernova is classed as Type 1a, and is catalogued under the name PTF11kly. The exploding star was one member of a stellar pair, known as a binary system, that had already burned away its hydrogen and helium in thermonuclear explosions, leaving only its carbon and oxygen to fuel the final outburst, Nugent said.

Because the light intensity of supernovas is well known, astronomers use them as "standard candles" to calculate the distances of far-off galaxies, and thus measure the rate at which the entire universe is expanding under the mysterious influence of what is called dark energy, Nugent explained.

Alex Filippenko, leader of a team of supernova observers at the UC Lick Observatory, said this newest one will prove valuable in helping astronomers to refine their distance calculations for those standard candles.

It should also shed new light on the exploding star's companion, Filippenko said. For example, astronomers might be able to determine whether the binary pair were both originally white dwarf stars, and whether the star that exploded might have been "stealing matter from its companion" as it built up toward its final blast, or - perhaps - whether both stars merged to explode in a single blast.

Every explosion of a supernova sends out bursts of all the elements that make up every bit of matter in the universe. "All the calcium in our bones, all the iron in our blood, all the chemicals in our bodies, came originally from supernovas that exploded even before the Earth was formed," Nugent said.

How to see it

Berkeley astronomer Peter Nugent explains how to see the supernova on You Tube: sfgate.com/ZLCS.

Learning more

Free talk on the supernova by Berkeley astronomer Peter Nugent.

Where: Chabot Space and Science Center, 10000 Skyline Blvd., Oakland.

When: Beginning at dusk Saturday as the center's telescopes focus on the Pinwheel Galaxy, where the cosmic explosion's light is visible.

E-mail David Perlman at dperlman@sfchronicle.com.



Read more: http://www.sfgate.com/cgi-bin/article ... K1L0P5I.DTL#ixzz1XNWcVlJE

Given that this was posted somewhere (no idea where - you didn't include source/link) early last Saturday, could "this weekend" have meant the one just passed?

A world vanishes, and you can watch

Saturday, September 03, 2011, 7:31 AM
By Michael W. Dominowski

The Pinwheel Galaxy, also known as Messier 101, is about 21 million light years from Earth.

STATEN ISLAND, N.Y. -- Stars come and go. We see them as unchanging, but we have not been here long. Stars are not as permanent as they appear to be.

Oftentimes, when they go, stars exit in a cataclysmic blaze of light, a supernova -- an explosion that engulfs not only the star but everything else in the cosmic vicinity.

Supernovas are mostly too far away for anyone but heavy-duty astronomers to see. But not always. If you have a small telescope or a good pair of binoculars, and if the sky is clear, you can see one from your backyard this weekend.

A white dwarf star in the Pinwheel Galaxy called PTF11kly, a couple of times bigger than our sun, suddenly and catastrophically exploded. The result was an exceptionally brilliant flash of light as most of the hapless star's mass was ejected into space.

If you'd like to have a look, take your best optics out to a dark place. Locate the constellation we call the Big Dipper. The position of the Big Dipper may be different than shown in the accompanying illustration, but that won't make a difference.

Draw an imaginary equilateral triangle, as shown, using the last two stars of the Dipper's handle as the base. The apex of the triangle will point to the Pinwheel Galaxy, where the supernova is occurring.

Supernovas, explosions that they are, tend to be brief events; they quickly peak and typically last no more than 18 days. This one was discovered on Aug. 23, so this is the weekend to go hunting for it.

Here's a factoid to wrap your head around: The supernova actually occurred 21 million years ago! We're seeing it now because the Pinwheel Galaxy, one of our nearest galactic neighbors, is nevertheless 21 million light years away. It took that long for the light from the spectacular demise of PTF11kly to reach us. This is probably as close to time travel as any of us will ever get.

To us, the supernova is just light. It poses no threat to Earth or its inhabitants.

By the way, if you cannot locate PTF11kly, you can always go for the consolation prize: Draw an imaginary line between the stars at the outer end of the bottom of the Big Dipper, from the bottom to the top edge, and extend it out to the nearest bright star. You've found Polaris, the North Star!

If you were to spend some time at this you'd discover that the dipper appears to rotate around the North Star, with the line we just drew always pointing to it. That's why the North Star is so valuable to navigators plying the trackless lands and oceans of the northern hemisphere.