Dec 17 2007

‘Death Star’ Galaxy Black Hole Fires at Neighboring Galaxy

‘Death Star’ Galaxy Black Hole Fires at Neighboring Galaxy: Image Credit: NASAWASHINGTON — Dec 17, `07 — A powerful jet from a super massive black hole is blasting a nearby galaxy, according to new findings from NASA observatories. This never-before witnessed galactic violence may have a profound effect on planets in the jet’s path and trigger a burst of star formation in its destructive wake.

Known as 3C321, the system contains two galaxies in orbit around each other. Data from NASA’s Chandra X-ray Observatory show both galaxies contain super massive black holes at their centers, but the larger galaxy has a jet emanating from the vicinity of its black hole. The smaller galaxy apparently has swung into the path of this jet.

This “death star” galaxy was discovered through the combined efforts of both space and ground-based telescopes. NASA’s Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope were part of the effort. The Very Large Array telescope, Socorro, N.M., and the Multi-Element Radio Linked Interferometer Network (MERLIN) telescopes in the United Kingdom also were needed for the finding.

“We’ve seen many jets produced by black holes, but this is the first time we’ve seen one punch into another galaxy like we’re seeing here,” said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. “This jet could be causing all sorts of problems for the smaller galaxy it is pummeling.”

Jets from super massive black holes produce high amounts of radiation, especially high-energy X-rays and gamma-rays, which can be lethal in large quantities. The combined effects of this radiation and particles traveling at almost the speed of light could severely damage the atmospheres of planets lying in the path of the jet. For example, protective layers of ozone in the upper atmosphere of planets could be destroyed.

Jets produced by super massive black holes transport enormous amounts of energy far from black holes and enable them to affect matter on scales vastly larger than the size of the black hole. Learning more about jets is a key goal for astrophysical research.

The effect of the jet on the companion galaxy is likely to be substantial, because the galaxies in 3C321 are extremely close at a distance of only about 20,000 light years apart. They lie approximately the same distance as Earth is from the center of the Milky Way galaxy.

A bright spot in the Very Large Array and MERLIN images shows where the jet has struck the side of the galaxy, dissipating some of the jet’s energy. The collision disrupted and deflected the jet.

Another unique aspect of the discovery in 3C321 is how relatively short-lived this event is on a cosmic time scale. Features seen in the Very Large Array and Chandra images indicate that the jet began impacting the galaxy about one million years ago, a small fraction of the system’s lifetime. This means such an alignment is quite rare in the nearby universe, making 3C321 an important opportunity to study such a phenomenon.

It is possible the event is not all bad news for the galaxy being struck by the jet. The massive influx of energy and radiation from the jet could induce the formation of large numbers of stars and planets after its initial wake of destruction is complete. More at NASA.


Nov 06 2007

Scientists Discover Record Fifth Planet Orbiting Nearby Star

Fifth_Planet_Orbiting_55_Cancri55_Cancri_top_and_our_own_Two_planetary_systems_Artists_concept_IllustratationPASADENA, Calif. — Nov 06, ‘07 — Astronomers have announced the discovery of a fifth planet circling 55 Cancri, a star beyond our solar system. The star now holds the record for number of confirmed extrasolar planets orbiting in a planetary system.

55 Cancri is located 41 light-years away in the constellation Cancer and has nearly the same mass and age as our sun. It is easily visible with binoculars. Researchers discovered the fifth planet using the Doppler technique, in which a planet’s gravitational tug is detected by the wobble it produces in the parent star. NASA and the National Science Foundation funded the research.

The newly discovered planet weighs about 45 times the mass of Earth and may be similar to Saturn in its composition and appearance. The planet is the fourth from 55 Cancri and completes one orbit every 260 days. Its location places the planet in the “habitable zone,” a band around the star where the temperature would permit liquid water to pool on solid surfaces. The distance from its star is approximately 116.7 million kilometers (72.5 million miles), slightly closer than Earth to our sun, but it orbits a star that is slightly fainter.

“The gas-giant planets in our solar system all have large moons,” said Debra Fischer, an astronomer at San Francisco State University and lead author of a paper that will appear in a future issue of the Astrophysical Journal. “If there is a moon orbiting this new, massive planet, it might have pools of liquid water on a rocky surface.”

Fischer and University of California, Berkeley, astronomer Geoff Marcy, plus a team of collaborators discovered this planet after careful observation of 2,000 nearby stars with the Shane telescope at Lick Observatory located on Mt. Hamilton, east of San Jose, Calif., and the W.M. Keck Observatory in Mauna Kea, Hawaii. More than 320 velocity measurements were required to disentangle signals from each of the planets.

“This is the first quintuple-planet system,” said Fischer. “This system has a dominant gas giant planet in an orbit similar to our Jupiter. Like the planets orbiting our sun, most of these planets reside in nearly circular orbits.”

“Discovering these five planets took us 18 years of continuous observations at Lick Observatory, starting before any extrasolar planets were known anywhere in the universe,” said Marcy, who contributed to the paper. “But finding five extrasolar planets orbiting a star is only one small step. Earth-like planets are the next destination.”

The planets around 55 Cancri are somewhat different from those orbiting our sun. The innermost planet is believed to be about the size of Neptune and whips around the star in less than three days at a distance from the star of approximately 5.6 million kilometers (3.5 million miles). The second planet is a little smaller than Jupiter and completes one orbit every 14.7 days at a distance from the star of approximately 18 million kilometers (11.2 million miles). The third planet, similar in mass to Saturn, completes one orbit every 44 days at a distance from the star of approximately 35.9 million kilometers (22.3 million miles). The newly discovered planet is the fourth planet. The fifth and most distant known planet is four times the mass of Jupiter and completes one orbit every 14 years at a distance from the star of approximately 867.6 million kilometers (539.1 million miles). It is still the only known Jupiter-like gas giant to reside as far away from its star as our own Jupiter is from our sun.

“This work marks an exciting next step in the search for worlds like our own,” said Michael Briley, an astronomer at the National Science Foundation. “To go from the first detections of planets around sun-like stars to finding a full-fledged solar system with a planet in a habitable zone in just 12 years is an amazing accomplishment and a testament to the years of hard work put in by these investigators.” More at NASA, University of California.