Astronomy Now Online

Top Stories

Brown dwarfs do form like stars

...astronomers have uncovered strong evidence that brown dwarfs – the dividing line between stars and planets – form like stars...

read more

Hubble’s snow globe
of stars a shaken snow globe of sparkling snow flakes frozen in time, Hubble has captured an instantaneous glimpse of the thousands of glittering stars moving about the globular cluster M13...

read more

Mars Science Laboratory delayed for two years

...the launch of NASA's Mars Science Laboratory has slipped to 2011, two years after the original schedule, in order to allow further hardware testing to ensure a maximum science return...

read more

Spaceflight Now +

Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

Become a subscriber
More video

Students discover planet orbiting rapidly rotating

hot star

Posted: 08 December, 2008

Three undergraduate students from Leiden University have discovered the first extrasolar planet orbiting a fast-rotating hot star.

Artist impression of the planet OGLE-TR-L9b circling its host star in about 2.5 days at a distance just three percent of the Earth-Sun distance from its star. The star itself is the hottest star with a planet ever discovered. Image: ESO/H. Zodetp.

As part of an undergraduate research project, Meta de Hoon, Remco van der Burg and Francis Vuijsje were testing an automated method to detect light fluctuations of some 15,700 stars in the OGLE database, compiled from about four years worth of data. One of the stars – OGLE-TR-L9 – was found to exhibit variations in brightness that could be explained by a transit of a planet in front of it, causing the star’s brightness to briefly dip. In this case its brightness was found to decrease by one percent for two hours every 2.5 days. The team used the GROND instrument on the 2.2 metre telescope at ESO's La Silla Observatory to follow up the observations, confirming the presence of a planet.

The discovery came as a complete surprise to project superviser Ignas Snellen. "The project was actually meant to teach the students how to develop search algorithms. But they did so well that there was time to test their algorithm on a so far unexplored database. At some point they came into my office and showed me this light curve. I was completely taken aback!"

In order to confirm the object’s status as a planet and not a brown dwarf or small star, the team made spectroscopic measurements using ESO’s Very Large Telescope,  which also revealed the star to be a hot 7,000 degrees, 1,200 degrees hotter than the Sun. It is also the hottest star with a planet ever discovered, and it is rotating very fast. The radial velocity method – that is used to discover most of the extrasolar planets already known – is less efficient on stars with these characteristics.

Undergraduate students Francis Vuijsje, Meta de Hoon, and Remco van der Burg (left to right) from Leiden University in the Netherlands proudly show off their discovery. Image: Leiden Observatory.

"This makes this discovery even more interesting," comments Snellen. The planet is five times as massive as Jupiter and circles its host star in about 2.5 days. It lies at only three percent of the Earth-Sun distance from its star, making it very hot and much larger than normal planets.

"It is exciting not just to find a planet, but to find one as unusual as this one; it turns out to be the first planet discovered around a fast rotating star, and it's also the hottest star found with a planet," says Meta. Although the planet has officially been assigned the tag OGLE2-TR-L9b, it has been nicknamed ReMeFra-1 by the students, after themselves.