A New Extrasolar Planet is Found Inside a Globular Cluster
July 10, 2003
Fascinating details of a new extrasolar planet were announced at a press conference on July 10. Fifteen years ago, a pulsar named PSR B1620-26 was discovered in the central region of the M4 globular cluster, which is 5,600 light years from Earth. The radio waves emanating from the pulsar showed that the star was wobbling, meaning that it was being tugged by the mass of a companion. This companion turned out to be a white dwarf star that was about one-third the mass of the sun, and has since been imaged by the Hubble Space Telescope. Eventually it was discovered that there was a smaller wobble in the pulsar’s movement, which suggested a less massive third companion in the system. A debate continued as to whether the third object was a tiny star, a brown dwarf, or a planet. The team of astronomers recently discovered the mass of the third object to be about 2.5 times as massive as Jupiter, which is consistent only with the idea that this is a planet orbiting a binary star system (see photos below). The current theory is that the planet actually formed around a star similar to our sun, which was then pulled into the core of the globular cluster. The gravitational pull of a larger star captured the smaller star and the planet. When the small star turned into a red giant, the larger star began to take material from the red giant, a process which accelerated the rotation of the pulsar. Eventually the red giant lost most of its material to the pulsar and turned into a white dwarf. The planet is a gas giant orbiting the stars at about the distance that Uranus is from our Sun, and takes a century for one revolution. It is the most distant planet found so far, and is also the oldest. Globular clusters, such as the one this star system is in, are tightly packed groupings of old stars. The M4 globular cluster is comprised of stars about 13 billion years old, almost as old as the universe itself. The astronomers believe that the planet is about the same age, which carries vast implications. So far, about 100 extrasolar planets have been discovered, and all of them are about the same age as the Earth, 4-5 billion years old. This discovery could mean that planets are a lot more common than was previously believed.
The Chandra X-ray Observatory Discovers an X-ray Jet Coming From a Pulsar
July 10, 2003
A wild jet of x-rays is shooting out from the Vela pulsar, located about 1,000 light years away. This is the most erratic stellar jet ever discovered, traveling at half the speed of light and reaching half a light year into space. The jet is also changing rapidly: within the space of two weeks, noticeable changes in shape and intensity can be seen, as pictured below. The bright rings or bubbles seen in the pulsar are now believed to be shockwaves resulting from the jet’s motion.
NASA Launches the Mars Opportunity Rovers
July 7, 2003
There are currently four spacecraft on their way to Mars. The most recent traveler is NASA’s Mars Opportunity rover, which will land near the Martian equator in January 2004. Opportunity’s twin spacecraft, Spirit, was launched on June 10, and will land in a crater on the opposite side of the planet from Opportunity. The main goal of the Opportunity and Spirit missions is to study evidence of water in the rocks and soil of the Martian surface. The European Space Agency launched its first planetary exploration mission on June 2, when Mars Express lifted off. In July 1998, Japan also launched its first planetary satellite, called Nozomi, but it encountered some problems which are making the trip to Mars last a lot longer than was expected.
Discovery of Nine New Extrasolar Planets Announced
July 4, 2003
At the Extrasolar Planets conference in Paris, the discovery of nine newly-identified planets was detailed. All nine planets were discovered with the same method, called the radial velocity method. Astronomers can measure the shifting spectral lines of a star that is being influenced by the mass of a nearby object, and in this way it is possible to infer the existence of a planet orbiting the star. The planets have masses from 0.7 to 7.8 times the mass of Jupiter, and are orbiting their respective stars at distances of between 0.46 and 3.3 astronomical units. One of the planets was discovered by a Japanese team, one by the Anglo-Australian Planet Search Team, one by the Geneva Extrasolar Planet Search Program and TODCOR, and the remaining six were discovered by the Geneva Extrasolar Planet Search Program led by Michel Mayor, one of the discoverers of the very first extrasolar planet.
Mars Odyssey Probe Provides Details on the Frozen Surface of Mars
June 26, 2003
The Odyssey spacecraft has been sending information back to Earth on the composition of Mars’ surface and its changing with the seasons. In the northern polar region of Mars, there are layers of dry ice which build up during the Martian winter and then thaw in the summer, resulting in a surface rich in water ice. The continued exploration of these environmental phenomena will be used in the future when manned missions to Mars are planned.