In early December, an international team of astronomers discovered an incredibly fast rotating star, rotating at a radial velocity of 1.6 million km/h (1 million mph), which is approximately 100 times faster than the sun rotates (roughly four times a day). If the star, dubbed VFTS (short for VLT-FLAMES Tarantula Survey) 102, spun any faster, the centrifugal forces would rip it apart.

Working at the European Southern Observatory’s Very Large Telescope at the Paranel Observatory in Chile, the team located VFTS 102 160,000 light-years away from the Earth in the Tarantula Nebula, which is part of the Large Magellanic Cloud, a satellite galaxy of our Milky Way galaxy. They detected the star because its traveling velocity was 30 km/s (70,000 mph) – much faster than those of other stars in the vicinity.

Philip Dufton, lead author of the paper that presents the team’s findings, stated, “The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had an unusual early life.” Dufton works at the Department of Physics and Astronomy at Queen’s University Belfast, Northern Ireland. “It was suspicious.”

The centrifugal forces of VFTS 102 (which is a blue giant and has twenty-five times the mass and 100,000 times the luminosity of the sun) are so great that the star has an oblate spheroid shape. Furthermore, they cause VFTS 102 to spin out a disk of plasma at its equator.

The team of astronomers speculate that VFTS 102 had a violent past. It may have been part of a binary star system in which it and its companion star closely rotated around each other. VFTS 102′s fast rotation may have come from the two stars being so close together, which could have caused the companion star to stream gas over to VFTS 102.

Another member of the team, Matteo Cantiello, an astrophysicist at the University of California, Santa Barbara, further explains in the university’s press release, “This gas falls onto the companion star, increasing the mass and spinning it up. Similar to a tennis ball spinning fast after being hit by a glancing blow, a star rotates quickly after being hit off-center by the in-falling gas.”

At some point, the companion star went supernova, expelling much of its gas. The intense explosion ejected VFTS 102, which was sent hurdling through space at the current velocity in which it was discovered. Presently, a supernova remnant and pulsar lie near the blue giant. That these two objects are located nearby VFTS 102 serves as evidence that supports the team’s hypothesis, as the supernova remnant and pulsar may belong to the late companion star, which may have collapsed into a neutron star following its exploding.

“This is a compelling story because it explains each of the unusual features that we’ve seen,” Dufton writes. “This star is certainly showing us unexpected sides of the short, but dramatic lives of the heaviest stars.”

The article Fastest Rotating Star Discovered appeared first on The Toonari Post - News, Powered by the People!.

An international research team of astronomers and astrophysicists were originally trying to find and study pulsars with the Kepler space telescope and the Kitt Peak Earth observatory in Arizona. However, the team got more than they bargained for. Later last week, they detected a star with a unusual pulsating rate: intervallic modulations, which occurred every 5.76 and 8.23 hours, caused the star to faintly flicker. Upon further studying, the team found out that these modulations were not produced by the star, and that is when they discovered two earth-sized exoplanets rotating around a red giant star well within its outer envelopes of gas.

“Having migrated so close, they probably plunged deep into the star’s envelope during the red giant phase, but survived,” says Stéphane Charpinet, who is the leader of the team and an astronomer at the University of Toulouse in France.

Before this finding, scientists in general assumed that planets engulfed by a red giant’s outer layers would be incinerated, and it is believed that this is to happen to the Earth since the Sun is fated to become a red giant. Now that these two exoplanets have been discovered, though, it seems that planets are able to endure stars’ transition to a red giant.

The star in question is named KIC 05807616 (also KOI 55, with “KOI” being the acronym for “Kepler Object of Interest”), formerly a main sequence star on the Hertzsprung-Russell Diagram, like our Sun. The two exoplanets, KOI 55-01 and KOI 55-02, revolve around KIC 05807616 less than approximately 900,000 kilometers and approximately one million kilometers, orbiting KIC 05807616 closer than Mercury orbits the Sun. They have the radii of .76 and .87 times the Earth’s respectively, making them the smallest exoplanets detected thus far.

According to another member of the team, Elizabeth ‘Betsy’ Green, an associate astronomer at the University of Arizona’s Steward Observatory, “The friction with the star’s envelope also strips the gaseous and liquid layers off the planet, leaving behind only some part of the solid core, scorched but still there.” This would account for KOI 55-01 and KOI 55-02′s small sizes.

The research team studied KIC 05807616 and found out that it had been transitioning to become a typical red giant, but since the nuclear reactions began occurring in the outer shells rather than in the core, it expanded, shedding its outer layers and jettisoning much of its mass. Due to the fact that KOI 55-01 and KOI 55-02 orbit KIC 05807616 closer than Mercury orbits the Sun, they may have may have helped KIC 05807616 with its transition, causing it to lose mass more rapidly by stripping its outer shells of gas.

The exoplanets ultimately affected KIC 05807616 enough to become a subdwarf B, which, entirely stripped of its outer layers, has the core of a red giant and the luminosity of a main sequence star, but smaller in mass. Upon finishing their research, the team concluded that planets can affect stellar evolution. “We think this is the first documented case of planets influencing a star’s evolution,” Charpinet states.

“We thought we had a pretty good understanding of what solar systems were like as long as we only knew one – ours,” says Green. “Now we are discovering a huge variety of solar systems that are nothing like ours, including, for the first time, remnant planets around a stellar core like this one.”

The article Two Exoplanets Survive Star’s Transition to Red Giant appeared first on The Toonari Post - News, Powered by the People!.