Hot Jupiter planets 'not regularly consumed by their stars'

Washington, June 7 (ANI): Stars have an alluring pull on planets, especially those in a class called hot Jupiters, which are gas giants that form farther from their stars before migrating inward and heating up.

Now, a new study using data from NASA's Kepler Space Telescope shows that hot Jupiters, despite their close-in orbits, are not regularly consumed by their stars.

Instead, the planets remain in fairly stable orbits for billions of years, until the day comes when they may ultimately get eaten.

"Eventually, all hot Jupiters get closer and closer to their stars, but in this study we are showing that this process stops before the stars get too close," said Peter Plavchan of NASA's Exoplanet Science Institute at the California Institute of Technology, Pasadena, Calif.

"The planets mostly stabilize once their orbits become circular, whipping around their stars every few days," he added.

The study is the first to demonstrate how the hot Jupiter planets halt their inward march on stars. Gravitational, or tidal, forces of a star circularize and stabilize a planet's orbit; when its orbit finally become circular, the migration ceases.

Hot Jupiters are giant balls of gas that resemble Jupiter in mass and composition. They don't begin life under the glare of a sun, but form in the chilly outer reaches, as Jupiter did in our solar system. Ultimately, the hot Jupiter planets head in toward their stars, a relatively rare process still poorly understood.

The new study answers questions about the end of the hot Jupiters' travels, revealing what put the brakes on their migration. Previously, there were a handful of theories explaining how this might occur. One theory proposed that the star's magnetic field prevented the planets from going any farther.

When a star is young, a planet-forming disk of material surrounds it. The material falls into the star-a process astronomers call accretion-but when it hits the magnetic bubble around it, called the magnetosphere, the material travels up and around the bubble, landing on the star from the top and bottom. This bubble could be halting migrating planets, so the theory went.

Another theory held that the planets stopped marching forward when they hit the end of the dusty portion of the planet-forming disk.

"This theory basically said that the dust road a planet travels on ends before the planet falls all the way into the star. A gap forms between the star and the inner edge of its dusty disk where the planets are thought to stop their migration," said co-author Chris Bilinski of the University of Arizona, Tucson.

And yet a third theory, the one the researchers found to be correct, proposed that a migrating planet stops once the star's tidal forces have completed their job of circularizing its orbit.

To test these and other scenarios, the scientists looked at 126 confirmed planets and more than 2,300 candidates. The majority of the candidates and some of the known planets were identified via NASA's Kepler mission. Kepler has found planets of all sizes and types, including rocky ones that orbit where temperatures are warm enough for liquid water.

The scientists looked at how the planets' distance from their stars varied depending on the mass of the star. It turns out that the various theories explaining what stops migrating planets differ in their predictions of how the mass of a star affects the orbit of the planet.

The "tidal forces" theory predicted that the hot Jupiters of more massive stars would orbit farther out, on average.

The survey results matched the "tidal forces" theory and even showed more of a correlation between massive stars and farther-out orbits than predicted.

This may be the end of the road for the mystery of what halts migrating planets, but the journey itself still poses many questions. As gas giants voyage inward, it is thought that they sometimes kick smaller, rocky planets out of the way, and with them any chance of life evolving.

The study was published recently in the Astrophysical Journal. (ANI)

Matches

MORE TOP STORIES TODAY

Royal test for Kings

Royal test for Kings

Preview — Clash of philosophies between Australia-centric teams More »

Have nothing to prove to anybody — Sehwag

Have nothing to prove to anybody — Sehwag

The Nawab of Najafgarh says a good run in IPL could help his chances of a comeback on India's tour to England in June. More »

Duminy steals first win for Delhi

Duminy steals first win for Delhi

Furious fifties by Duminy and Dinesh Karthik end a long losing streak for the Daredevils. More »

Five things England must do to bounce back

Five things England must do to bounce back

England have appointed a new head coach in Peter Moores. More »

AB, Parthiv seal Bangalore's second win

AB, Parthiv seal Bangalore's second win

Royal Challengers overcame a stutter to cruise to the small target they were set by Mumbai Indians. More »

‘Felt like helpless minority’

‘Felt like helpless minority’

Former BCCI treasurer Ajay Shirke says emotions got the better of the Srinivasan and he tried to oversimplify things by calling Meiyappan an “enthusia… More »

No way back for Pietersen: ECB

No way back for Pietersen: ECB

Kevin Pietersen's hopes of reviving his international career appeared to end Saturday when ECB managing director Paul Downton said there was 'no way back'… More »

The world record that nearly wasn't

The world record that nearly wasn't

Twenty years ago this week, Brian Lara became Test cricket's highest scorer, but he almost didn't make it. More »

Srinivasan can attend BCCI meeting

Srinivasan can attend BCCI meeting

His status as president of TNCA makes him eligible to attend the Working Committee meeting on Sunday. More »

Moores gets second stint as coach

Moores gets second stint as coach

In a two-year spell from 2007 to 2009, the 51-year-old Moores led England in seven Test series. More »

Bangladesh senior players to see shrink

Bangladesh senior players to see shrink

Bangladesh's senior players will have three sessions with a psychological skill development coach later this month More »

Maxwell carves his parallel universe

Maxwell carves his parallel universe

Glenn Maxwell seems to project an icy disdain when at the crease. Match situations rarely faze him and the bubble in which he plays excludes everyone … More »

BCCI is not anybody’s property — Dalmiya

BCCI is not anybody’s property — Dalmiya

Dalmiya feels that Srinivasan’s ‘power hungry’ attitude isn’t helping matters. More »

Tough for bowlers: Saeed Ajmal

Tough for bowlers: Saeed Ajmal

The 36-year-old believes the T20 format and rule changes in 50-over matches have made a real difference. More »

KP ridicules idea of day-night Tests

KP ridicules idea of day-night Tests

Kevin Pietersen has ridiculed the idea of day-night Test cricket, saying the game would be so different to proper Test cricket that we will need a whole… More »

Rajasthan edge low-scoring thriller

Rajasthan edge low-scoring thriller

The bowlers restricted Hyderabad to 133 for 6 before Rahane and Binny took Rajasthan over the line. More »

Maxwell blitz takes Punjab home

Maxwell blitz takes Punjab home

The Kings XI batsman blasted a 43-ball 95 to help his team pull off a massive chase against Chennai Super Kings. More »

BCCI members want independent probe

BCCI members want independent probe

The board members are realising after the Supreme Court's observations that something has to be done — IS Bindra More »

'BCCI lacks leaders to take on Srini'

'BCCI lacks leaders to take on Srini'

Two former BCCI presidents, Shashank Manohar and Jagmohan Dalmiya, have reacted strongly to the news of the BCCI calling an emergent meeting on Sunday… More »

Delhi look for first points against confident Kolkata

Delhi look for first points against confident Kolkata

Preview — The threat of Sunil Narine looms large again. More »

Bangalore vs Mumbai: A battle of the big-hitters

Bangalore vs Mumbai: A battle of the big-hitters

Preview — Given the firepower in both line-ups, Dubai crowd may see another high-scorer More »

Yuvraj tees off to Sharjah's delight

Yuvraj tees off to Sharjah's delight

Yuvraj Singh was hardly convincing to begin with against Delhi, but a big dose of crowd support and a helping of poor bowling meant he had the opportunity… More »

Stressed Trott stands down again

Stressed Trott stands down again

The England and Wales Cricket Board (ECB) on Friday confirmed that batsman Jonathan Trott is to take another break from all cricket with immediate eff… More »

PCB starts another coach hunt

PCB starts another coach hunt

The PCB has decided to not extend the contracts of head coach Moin Khan, fielding coach Shoaib Mohammad and batting consultant Zaheer Abbas, and has invited… More »