In Hollywood, the biggest stars are measured by their box office appeal, the roles they get in movies, or by millions of votes cast by the public on “American Idol.” But in astronomy, how do you know what the hottest stars in the universe are? What makes a star so special it deserves our awe and appreciation?
Some stars capture our imagination because they are the best candidates for planets teeming with life. Others might help us understand the origin of our own solar system, while still others stand out because they host planets that are just plain bizarre.
A number of leading planet hunters were asked to name their most intriguing stars. Here are their top 10 choices for the most interesting stars in the universe.
10. Mr. Spock’s Neighborhood: 40 Eridani A
This is the star identified in “Star Trek” lore as the location of planet Vulcan, Mr. Spock’s home world. So far, no planets have been found around this star, a K dwarf smaller and cooler than our sun. But research conducted by Dr. Angelle Tanner, a scientist with the planned SIM PlanetQuest mission indicates there’s no reason a habitable planet couldn’t have formed around that star. The mission will have the capability to find Vulcan, if it’s there, as part of its search for habitable planets around.
9. A Lab for Origins: HD 69830
This sun-like star, located 40 light-years from Earth, is particularly fascinating to scientists studying the origins of solar systems. It contains a trio of Neptune-size planets – including one in the habitable zone – and NASA’s Spitzer Space Telescope has spotted a dusty asteroid belt surrounding the star, providing astronomers a rare window into the process by which rocky planets form. “This is the premiere laboratory for observing the interactions between asteroid belts, dust, and the planetary system,” said Dr. Charles Beichman, lead author of a paper on Spitzer’s discovery. “We can’t directly see other terrestrial planets, but now we can study their dusty fossils.”
8. A lot like Home: 55 Cancri
Of all the planetary systems discovered out there so far, 55 Cancri generates the most warm, fuzzy feelings. It’s a place that looks a lot like home. This system hosts at least four planets, including one of the smallest detected so far and a gas giant the size of Jupiter and with the same location relative to its sun as Jupiter’s in relation to our sun. Most intriguing of all, however, is 55 Cancri’s potential to harbor smaller, terrestrial planets in the habitable zone – planets that elude detection by current instruments.
7. Light from Far, Far Away: HD 209458 & HD 189733
These two stars represent an astronomical milestone: the first direct detection of spectra or molecular fingerprints, in the atmospheres of faraway worlds beyond out solar system. The landmark achievement by the Spitzer Space Telescope was a significant step toward being able to detect possible life on rocky exoplanets, and came years before astronomers had anticipated. Data from the two gaseous planets, which orbit very close to their suns, indicate they are drier and cloudier than predicted, with no signs of water in their atmospheres.
6. Hot Spot for Life?: Epsilon Indi A
Astronomer Margaret Turnbull of the Carnegie Institution of Washington has complied a list of more than 17,000 potentially “habitable stellar systems” – candidate stars where some form of life might thrive. She named Epsilon Indi A, about 11.8 light-years away, as her top candidate for further investigation by NASA’s planned Terrestrial Planet Finder mission.
5. The First Exoplanet: 51 Pegasi
In 1995, Swiss astronomers reported they had discovered the first planet beyond our solar system, in orbit around the star 51 Pegasi, 48 light-years from Earth, and the field of extrasolar planet research was born. Although the planet was unsuitable for life, the star could also host smaller, terrestrial planets, as yet undetected. Finding out whether smaller, Earth-like planets exist we will have to await the further deployment of more sensitive, space-base instruments.
4. All Puffed Up: HAT-P-1
In September 2006, astronomers announced the discovery of an entirely new class of planet. With a radius about 1.38 times that of Jupiter, this marshmallow-like orb is only about one-fourth the density of water. Like Saturn, HAT-P-1 b would float in a bathtub, if you could fin a tub big enough to hold it, but it would float almost three times higher. As of now, the reason for it’s swollen condition remains a mystery – one that astronomer hope to sove through follow-up observations.
3. Star Light, Star Bright: Pollux
Pollux, also known as Bet Geminroum, is one of the brightest and most familiar stars in the night sky. Recently, scientists have discovered that it harbors a secret: a hidden planet, about three times the size of Jupiter. Next time you wish upon a star, why not make it Pollux?
2. Day and Night World: Upsilon Andromedae
In October 2007, astronomers announced that Nasa’s Spitzer Space Telescope had made the first measurements of the day and night temperatures of a planet outside our solar system. Upsilon Andromedae b is an amazingly exotic world: a gas giant planet circling very close to its sun, always hot as fire on one side, and potentially cold as ice on the other. this was the first time any kind of variation had been seen across the surface of an extrasolar planet.
1. A Habitable World?: Gliese 581
In April, 2007, European astronomers made a historic announcement: They had detected the first potentially habitable planet orbiting a star other than the sun. The planet Gliese 581b orbits a red dwarf, a type of star very different from our sun. Nonetheless, the planet is small enough to be solid, rather than gaseous., and the researchers said it orbits in the sweet spot where liquid water could be present.
Reprinted with permission courtesy NASA/JPL-Caltech. JPL-authored documents are sponsored by NASA under Contract NAS7-030010.