First pulsating carbon white dwarf.  Image Credit:  Sloan Digital Sky Survey

New Type of White Dwarf Stars Discovered

1 May , 2008 by

Most of the stars in the universe will end their lives as white dwarfs, the class of star that’s just a remnant of the star’s former self when all the nuclear fuel in the star’s core has burned. Studying these white dwarfs gives astronomers an important view of the endpoint of most stars. Recently, researchers from the University of Texas have confirmed the existence of a new type of dwarf star, a “pulsating carbon white dwarf.” Since pulsating stars can reveal the inner workings of these stars, astronomers are hoping now to be able to learn more about what goes on inside white dwarf stars.

Until recently, astronomers knew of only two types of white dwarf stars: those that have an outer layer of hydrogen (about 80 percent), and about those with an outer layer of helium (about 20 percent), whose hydrogen shells have somehow been stripped away. Then in 2007, a third type was discovered, a very rare “hot carbon white dwarf.” These stars have had both their hydrogen and helium shells stripped off, leaving their carbon layer exposed.

After these new carbon white dwarfs were announced, Michael H. Montgomery from the University of Texas calculated that pulsations in these stars were possible. Similar to how geologists study seismic waves from earthquakes to understand what goes on in Earth’s interior astronomers can study the changes in light from a pulsating star to “look” into the star’s interior. In fact, this type of star-study is called “asteroseismology.”

Montgomery and his team began a systematic study of carbon white dwarfs with the Struve Telescope at McDonald Observatory, looking for pulsators. They discovered a pulsating star about 800 light-years away in the constellation Ursa Major, (called SDSS J142625.71+575218.3) fits the into this category. Its light intensity varies regularly by nearly two percent about every eight minutes.

“The discovery that one of these stars is pulsating is remarkably important,” said National Science Foundation astronomer Michael Briley. “This will allow us to probe the white dwarf’s interior, which in turn should help us solve the riddle of where the carbon white dwarfs come from and what happens to their hydrogen and helium.”

The star lies about ten degrees east northeast of Mizar, the middle star in the handle of the Big Dipper. This white dwarf has about the same mass as our Sun, but its diameter is smaller than Earth’s. The star has a temperature of 35,000 degrees Fahrenheit (19,500 C), and is only 1/600th as bright as the Sun.

Original News Source: McDonald Observatory Press Release


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pete
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pete
May 1, 2008 3:09 PM

Interesting. Now, somebody ought to develop an observing program like…Long Undulating Carbon Yield. Then we can have LUCY in the Sky….with Diamonds. pete

br0g
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br0g
May 1, 2008 5:07 PM

pete: that was terrible.

Mav
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Mav
May 1, 2008 5:45 PM

Pete:

+1 for beatles reference
-10 for over-used beatles reference

/hello fark

Hai
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Hai
May 1, 2008 6:57 PM

Does Oxygen White Dwarf exist?

leafguy
Member
May 1, 2008 7:31 PM

*Shakes head at Lucy joke*

Bunnyman
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May 1, 2008 7:40 PM

Throw in seven of the hydrogen/helium remnants and you’ve got Carbon White and the Seven Dwarfs.

Jozef
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Jozef
May 1, 2008 7:52 PM

Best Beatles reference ever

Terragen
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Terragen
May 1, 2008 8:21 PM

All over-wrought and under-whelming references aside, this article made me think “like a diamond in the sky” and I wonder if these carbon starts are just pumping out diamonds?
And are there advanced races that harvest star-forged diamonds, not to mention the diamonds supposedly raining down on Neptune!?

These things I wonder…

Andrew James
Member
May 2, 2008 2:22 AM

To understand the nature of white dwarfs and something about the nature of their evolution, I would recommend reader look at Icko Iben Jr, 1985 article “The Life and Times of an Intermediate Mass Star – in Isolation/in a Binary”; QJRAS, 26, 1, (1985)
You can download the article from the ADS;
http://adsabs.harvard.edu/abs/1985QJRAS..26….1I

or directly download the article in pdf at;
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1985QJRAS..26….1I&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf

Although this is a technical article, reader here should easily understand it. Perhaps the best section is Figure 19, which shows the mass of the white dwarf against the initial star mass, and shows the typical composition of the white dwarf as mass increases.-including the Carbon-Oxygen White Dwarfs (CO White Dwarfs).

venki
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May 2, 2008 1:32 AM

Posted this link in http://www.surfurls.com

Vanamonde
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Vanamonde
May 2, 2008 1:38 AM

If this is a white dwarf, why does it look so blue? About the bluest star I have ever seen.

Andrew James
Member
May 2, 2008 9:19 AM
Those interested might like to read the “Life and Times of an Intermediate Mass Star – in Isolation/in a Binary”; QJRAS, 26, 1, (1985) You can download the article from the ADS; Although this is a technical article, reader here should easily understand it. Perhaps the best section is Figure 19, which shows the mass of the white dwarf against the initial star mass, and shows the typical composition of the white dwarf as mass increases.-including the Carbon-Oxygen White Dwarfs (CO White Dwarfs) . Furthermore, this article confuses me, as the three types of white dwarfs, at least there ashes, Helium, Carbon-Oxygen, Oxygen-Neon White Dwarfs. Also Carbon-Oxygen white dwarfs have been established for ages, though hot ones are… Read more »
RUF
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RUF
May 2, 2008 6:25 PM

Would these be DQ class white dwarfs?

Ricky Diaz
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Ricky Diaz
May 3, 2008 2:18 AM
This discovery took place over a year ago. Interested in pulsating neutron stars or pulsars, I searched “pulsating white dwarfs” at google.com just to check in case it was true, because there, I have good luck sometimes searching for something I didn’t know about. Like a pulsar spinning over 1000 times per second, a white dwarf completing a rotation in minutes, a neutron star spinning only once every 12 seconds, a planet around a quadruple star system, or a planet that orbits it’s star in less than 2 days, the Sun possibly having a red dwarf star or brown dwarf companion, a new mini-solar system forming around a brown dwarf only 12 times Jupiter’s mass, and a mass… Read more »
bob
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bob
May 3, 2008 9:25 AM
As for what causes it, better equipment will reveal more data that we cannot see now. It is likely that the pulsing may be caused by material drawn toward the WD gravitationally while the strong magnetic field interacts with it periodically or funnels it down to the surface which then radiates it outward. Degenerate matter has the habit of shrinking when more matter is added and there is unlikely any symmetrical infall of matter onto the WD. The shrinking is a change in position of matter in the magetic field and that should induce a pulse. The degenerate electrons cannot be the source of the magnetic field pulses but this does not mean that the nuclei are degenerate.… Read more »
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