Category Archives: astronomy

astronomy, exoplanets

Where are Planets the Most Common in Our Galaxy?

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Maybe Everywhere, It Turns Out

This shows where Kepler has aimed its planet-finding instruments (where it says “most known exoplanets”; OGLE is scanning the entire sky, and has found several planets between the Sun and the galactic bulge. Courtesy NASA.

As everybody knows, the Kepler Mission has been finding planets in the little section of the galaxy it has been studying for some years now. More than 4,000 planet candidates are out there, spied out by Kepler’s instruments. But, are those the only planets “out there”? Of course not. Astronomers think that exoplanets are ubiquitous—that is, they’re everywhere. One in five stars has Earth-similar planets orbiting in their habitable zones (the regions where liquid water could exist on their surfaces). Most stars in our galaxy have at least one planet.

That’s pretty reassuring if you’re into the search for other worlds. So, here’s some more good news: Spitzer Space Telescope and a ground-based observatory called the OGLE Warsaw Telescope at Las Campanas Observatory in Chile, spied a gas giant planet about 13,000 light-years away from us toward the central bar of the Milky Way Galaxy. OGLE was built to survey the sky looking for planets, and Spitzer is uniquely positioned to give us an infrared look at planets once they’re found.

This artist’s conception shows a planet half as massive as Jupiter located 13,000 light-years from Earth. It was detected by the Optical Gravitational Lensing Experiment and NASA’s Spitzer Space Telescope using microlensing. Spitzer provided parallax measurements that allowed scientists to determine how far away the planet is. Christine Pulliam (CfA)

Astronomers are interested to find out if planets are more common in the region where this one was found, part of the galaxy’s central bulge. The center of the galaxy is likely to give us a view of more stars, and more stars means more chances for an event called “microlensing” to take place. That happens when one star passes between us and other one; as it does, the nearer star’s gravity acts as a lens to magnify and brighten the more distant star’s light. It can also reveal the presence of a planet circling the foreground star.

Astronomers are using microlensing to find and characterize planets up to 27,000 light-years away in the central bulge of our galaxy, where star crossings are more common. This technique has yielded about 30 planet discoveries so far, and the most distant known planet it has found is about 25,000 light-years away from us.

Astronomers use OGLE to find the planets, and Spitzer to pinpoint their exact locations, which is a long and complex process. The results, however, are expanding the number of known planets and their locations, and giving even more evidence to astronomers that planets are pretty commonplace across the galaxy.

astronomy

Take a Fantastic Flight Through a Stellar Creche

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Celebrating 25 Years with Another Great Image

 

This is what you get when scientists peer into the heart of a starbirth region: lots of hot young stars, radiating ultraviolet light and blasting out strong winds that are eating away at the leftovers of their birth cloud. The still image of this is amazing, but when you let visualization experts loose on it, you get an amazing flythrough of a stellar créche.  The object Hubble Space Telescope observed is called Gum 28, which lies about 20,000 light-years away from us.

As we glide through the remains of the birth clouds, we’re aimed directly at a cluster of about 3,000 stars called Westerlund 2. They are about 2 million years old, which makes them toddlers compared to stars like our Sun, which is about 4.5 billion years old.

Put on some good space music and sail through the stars.