When it runs out of fuel that is. One way to get an idea is to study similar stars. Two astronomers did just that using the Chandra X-ray Observatory to discover a shell of superheated gas around a dying star in the Milky Way galaxy.

Joel Kastner, professor of imaging science at the Rochester Institute of Technology, and Rodolpho Montez, a graduate student in physics and astronomy at the University of Rochester, will present their results today at the American Astronomical Society meeting in Minneapolis.

Their discovery shows how material ejected at two million miles per hour during the final, dying stages of sun-like stars can heat previously ejected gas to the point where it will emit X-rays. The study also offers new insight into how long the ejected gas around dying stars can persist in such a superheated state.

According to Kastner, the hot gas shows up in high-resolution Chandra X-ray images of the planetary nebula NGC 40, (see image) which is located about 3,000 light years away from Earth in the direction of the constellation Cepheus.

“Planetary nebulae are shells of gas ejected by dying stars,” Kastner explains. “They offer astronomers a ‘forecast’ of what could happen to our own sun about five billion years from now–when it finally exhausts the reservoir of hydrogen gas at its core that presently provides its source of nuclear power.”

Read the whole story here from the source: SpaceRef/Rochester Institute of Technology

Image Credit: NASA/ RIT (Kastner/ Montez)

A scientist using NASA’s Chandra X-ray Observatory has found evidence to suggest two white dwarf stars are orbiting each other and are destined to merge. The two suns, white dwarfs actually, may have the smallest orbit of any known binary system. The pair are only about one fifth as far away from each other as the moon is from Earth. The system is know as J0806 and shows a periodic variation of 321.5 seconds it is a little unclear whether the variation represents the spin of one of the stars, which would be pretty amazing or whether pair are orbiting each other at rate which would be astounding — that’s only about 5 minutes.

A white dwarf is what is left of some stars (like our sun) after they use up their fuel. The basically shine with residual heat from when it was still producing energy from nuclear reactions. While generally only about the size of the Earth they have the mass of the sun so they are quite dense. A lump of white dwarf sun about the size sugar cube would weigh about as much as a car.

The other interesting thing is the data also suggests that gravitational waves are carrying energy away from the star system. Einstein predicted in his General Theory of Relativity a binary system should emit gravitational waves that travel away from the system and cause the stars to move closer together and the orbital period will decrease. The decrease can be measured by Chandra. The orbital period is apparently decreasing but only by 1.2 milliseconds a year, still, a rate consistent with the theory that predicted loss of energy due to gravitational waves.

From the press release:

If confirmed, J0806 could be one of the brightest sources of gravitational waves in our galaxy,” said Tod Strohmayer of NASA’s Goddard Space Flight Center, Greenbelt, Md.

“It could be among the first to be directly detected with an upcoming space mission called LISA, the Laser Interferometer Space Antenna.”

Strohmayer presented data yesterday at the American Astronomical Society meeting in Minneapolis and further added:

“It’s either the most compact binary known or one of the most unusual systems we’ve ever seen. Either way it’s got a great story to tell.”

Source: Marshal Space Flight Center

More on the binary system

Photo: ESO (from 2002)

Check out this abstract from the 206th Meeting of the American Astronomical Society now being held in Minneapolis:

[5.01] The Slacker Astronomy Podcast
A. Price (AAVSO), P. Gay (Harvard University), T. Searle (AAVSO)

The Slacker Astronomy podcast is a weekly audio show about astronomy. Available in MP3 format, it is syndicated using RSS and XML feeds that make downloading snap. Each show presents a recent astronomical news item in an entertaining, humorous, and easy-to-understand manner that informs yet respects the intelligence of the listener.

First launched on 05 Feb 14, the show has grown to over 5,000 weekly subscribers as of 05 April 01 without any formal publicity. Response has been over overwhelmingly positive, with strong reviews coming from other popular podcasts and coverage on the front page of the MSNBC.com science section. Our only consistent negative feedback is that the show is too short and too infrequent. This demonstrates a strong need to add content.

We believe podcasting provides a unique mechanism to extend astronomical outreach to the younger generations and to those who lead busy lifestyles. Our formula is proving successful and we are looking for ways to quantify our impact and measure our demographic so that we can serve them better.

Lots of good info coming out of this meeting, I will try to get some of it on here…probably tomorrow.

There is more and more evidence that Phoebe came from elsewhere in the solar system and was captured by Saturn’s gravitational pull.

One source of evidence comes by using Cassini’s Visible and Infrared Mapping Spectrometer (VIMS), developed by a team of US (JPL), French and Italian (ASI) scientists and engineers. The science team is made by a large international group of US, Italian, French and German scientists led by the University of Arizona.

Recent results from VIMS suggest that Phoebe was gravitationally ‘captured’ by Saturn, having formed from ice and rocks ‘accreting’, or joining together, outside the region of the ‘solar nebula’ gas and dust in which Saturn formed.

Another interesting thing about Phoebe is its orbit is in the opposite direction and inclined at different angle to Saturn’s other moons.

If Phoebe originated in the region of the main asteroid belt, it should consist largely of silicate rocks and magmas with relatively high amounts of heavier elements. Instead the presence of highly volatile substances (i.e. lots of water and carbon dioxide ice or other carbon-based compounds) seems to indicate otherwise in fact it could have formed where the Kuiper belt objects originated in the ‘volatile-rich’ outer solar nebula. This would mean of course it came from the “other” direction.

The image at the top left is a mosaic of two images the Cassini-Huygens spacecraft took on a fly-by on June 11, 2004.

Small bright craters in the image of the battered little moon are probably fairly young features. This has been observed on other icy satellites, such as Ganymede around Jupiter.

The image on the bottom shows bright ‘wispy’ streaks thought to be ice revealed by subsidence of crater walls, are leading to the view that Phoebe is an icy-rich body overlain with a thin layer of dark material.

Click for a slightly larger image.

Significant slumping has occurred along the crater wall at top left.
The slumping of material might have been caused by a small projectile punching into the steep slope of the wall of a pre-existing larger crater. Another possibility is that the material collapsed when triggered by another impact elsewhere on Phoebe.

Click for a much larger image (143k). Expand the picture to full size and take a good look, really good detail.

A much more detailed story is available from the source of this post: ESA

Image Credit: NASA/JPL/Space Science Institute

Four different wallpapers, one for each week of June. Hubble is the theme.

	SIZE 800 1024	M42 Source: ESA Hubble
	SIZE 800 1024	Tarantula Galaxy Source: ESA Hubble
	SIZE 800 1024	Barred Galaxy Source: ESA Hubble
	SIZE 800 1024	Eagle Nebula Source: ESA Hubble

To use just click on the size you want. Typically 800 for desktops and 1024 for laptops, but check your monitor settings. When the picture loads, right click and click on "Set as Background".

The upper level low pressure system that bothered us for a long spell has left. The sky was nice earlier but it is now getting ready to thunderstorm on us.

But hey “it ain’t snowing”….

Now we are in for another upper level low so they say. However, it looks like the new one isn’t going to be hanging around for weeks. This is good. I want to get outside and see if my improvements were improvements at all. Plus I would like to get some more imaging practice in. The image here of Jupiter was taken the last time I could get out and also the last time we had clear skies –a week ago Thursday. It isn’t great nor is it terrible and while I am getting there, I have a long way to go before I will be satisfied. I cropped out most of the sky, lots of black.

Better shut down so the blog doesn’t get toasted by lightning!