White Dwarf Stars Consume Rocky Bodies

August 16, 2011 by Tammy Plotner, Universe Today
This artist's concept shows a star encircled by a disk of gas and dust, the raw materials from which rocky planets such as Earth are thought to form. Image credit: NASA/JPL-Caltech

“I love rocky road… So won’t you buy another gallon, baby…” Yeah. We all love rocky road ice cream, but what do stars like to snack on? In the case of the white dwarf star it would appear that a rocky body – similar to Earth – could be a preferred blend. At one time astronomers thought the dense, elderly stars were just gathering dust… but apparently it’s the “bones” left-over from a planetary knosh.

Using the Keck I telescope on Mauna Kea in Hawaii, astronomer and study coauthor Ben Zuckerman of UCLA and his team have been studying two helium-dominated white dwarfs – stars PG1225-079 and HS2253+8023. About the size of Earth, but as massive as the Sun, these stars have a zone of “pollution” around them that’s around equal in mass to asteroid Ceres.

“This means that planet-like rocky material is forming at Earth-like distances or temperatures from these stars,” says Zuckerman. He also notes that it’s still unclear whether the material is from a planet, planet-like bodies or an asteroid, but it is clear that there’s a lot of it.

Because looking at a white dwarf star for evidence of solar systems wasn’t really a high priority consideration, these new findings could lend researchers some new clues. It’s not just dust – it’s dust with a signature. Because the white dwarf has a “clean” atmosphere of hydrogen or helium, finding other components in its spectra could point to a one-time presence of Earth-like planets. Zuckerman says that between 25 and 30 percent of have orbital systems that contain both large planets and smaller rocky bodies. After the dwarf forms, larger, Jupiter-mass planets can perturb the orbits of smaller bodies and bounce them toward the star.

“This is the first hint that despite all the oddball planetary systems we see, some of them must be more like our own,” says astronomer John Debes of NASA’s Goddard Space Flight Center in Greenbelt, Md., who was not involved in the study. “We think that most of these systems that show pollution must in some way approximate ours.”

How do they know if they have a candidate? Star PG1225-079 has a mix of elements, including magnesium, iron and nickel (along with others). These were found in ratios very similar in overall content of Earth. Star HS2253+8023 contains more than 85 percent oxygen, magnesium, silicon and iron. Not only are these assessments also similar to our planet, but found in the correct range where this type of rocky body should have formed.

“I’ve never seen so much detail in spectra,” says astronomer Jay Holberg of the University of Arizona in Tucson, who was not involved in the study. “People have seen iron and calcium and other things in these , but [this group has] gone off and found a whole slew of other elements.”

Pass the spoon… Before it melts.

Explore further: Solar systems around dead Suns?

Related Stories

Solar systems around dead Suns?

April 20, 2009

(PhysOrg.com) -- Using NASA’s Spitzer Space Telescope, an international team of astronomers have found that at least 1 in 100 white dwarf stars show evidence of orbiting asteroids and rocky planets, suggesting these objects ...

Coming to a solar system near you… super-Earth!

August 8, 2011

It is our general understanding of solar system composition that planets fall into two categories: gas giants like Jupiter, Saturn, Neptune and Uranus… and rocky bodies that support some type of atmosphere like Earth, ...

Dead Stars Tell Story of Planet Birth

January 5, 2009

(PhysOrg.com) -- Astronomers have turned to an unexpected place to study the evolution of planets -- dead stars. Observations made with NASA's Spitzer Space Telescope reveal six dead "white dwarf" stars littered with the ...

Ovation for a stellar senior

June 16, 2011

Residing in space 6500 light-years away in the constellation of Cepheus, an aged star designated as IRAS 22036+5306 is making its final curtain call. Its stellar play is ending and its making the transition through the protoplanetary, ...

A supernova that's super different

June 3, 2011

A researcher at the Harvard-Smithsonian Center for Astrophysics believes that a new kind of supernova is at work in recent observations of bright but short-lasting stellar explosions that don’t appear to fit known categories.

Exomoons could be excellent incubators

June 20, 2011

With the arrival of the Cassini–Huygens mission in 2004 to Saturn’s satellite Titan, we terrestrials became acutely aware that similar moons could be orbiting similarly large planets in other solar systems besides ...

Recommended for you

Astronomers identify purest, most massive brown dwarf

March 24, 2017

An international team of astronomers has identified a record breaking brown dwarf (a star too small for nuclear fusion) with the 'purest' composition and the highest mass yet known. The object, known as SDSS J0104+1535, is ...

Spacewalk a success for French, US astronauts

March 24, 2017

A French and an American astronaut floated outside the International Space Station Friday on a successful spacewalk to upgrade the orbiting outpost for the arrival of future space crews.

OSIRIS-REx asteroid search tests instruments, science team

March 24, 2017

During an almost two-week search, NASA's OSIRIS-REx mission team activated the spacecraft's MapCam imager and scanned part of the surrounding space for elusive Earth-Trojan asteroids—objects that scientists believe may ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.