Astronomers are getting to know the neighbors better. Our sun resides within a spiral arm of our Milky Way galaxy about two-thirds of the way out from the center. It lives in a fairly calm, suburb-like area with an average number of stellar residents. Recently, NASA’s Wide-field Infrared Survey Explorer, or WISE, has been turning up a new crowd of stars close to home: the coldest of the brown dwarf family of “failed” stars.
Now, just as scientists are “meeting and greeting” the new neighbors, WISE has a surprise in store: there are far fewer brown dwarfs around us than predicted.
“This is a really illuminating result,” said Davy Kirkpatrick of the WISE science team at NASA’s Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. “Now that we’re finally seeing the solar neighborhood with keener, infrared vision, the little guys aren’t as prevalent as we once thought.”
PASADENA, Calif. — Observations from NASA’s Wide-field Infrared Survey Explorer (WISE) have led to the best assessment yet of our solar system’s population of potentially hazardous asteroids. The results reveal new information about their total numbers, origins and the possible dangers they may pose.
Potentially hazardous asteroids, or PHAs, are a subset of the larger group of near-Earth asteroids. The PHAs have the closest orbits to Earth’s, coming within five million miles (about eight million kilometers), and they are big enough to survive passing through Earth’s atmosphere and cause damage on a regional, or greater, scale.
The new results come from the asteroid-hunting portion of the WISE mission, called NEOWISE. The project sampled 107 PHAs to make predictions about the entire population as a whole. Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet (about 100 meters). So far, an estimated 20 to 30 percent of these objects have been found.
NASA unveiled a new atlas and catalog of the entire infrared sky today showing more than a half billion stars, galaxies and other objects captured by the Wide-field Infrared Survey Explorer (WISE) mission.
“Today, WISE delivers the fruit of 14 years of effort to the astronomical community,” said Edward Wright, WISE principal investigator at UCLA, who first began working on the mission with other team members in 1998.
WISE launched Dec. 14, 2009, and mapped the entire sky in 2010 with vastly better sensitivity than its predecessors. It collected more than 2.7 million images taken at four infrared wavelengths of light, capturing everything from nearby asteroids to distant galaxies. Since then, the team has been processing more than 15 trillion bytes of returned data. A preliminary release of WISE data, covering the first half of the sky surveyed, was made last April.
To visible-light telescopes, this star-forming cloud appears to be chomping through the cosmos, earning it the nickname the “Pacman” nebula, like the famous Pac-Man video game that debuted in 1980. When viewed in infrared light by NASA’s Wide-field Infrared Survey Explorer, or WISE, the Pacman takes on a new appearance. In place of its typical, triangle-shaped mouth is a new set of lower, sharp-looking teeth. The Pacman is located at the top of the picture, taking a bite in the direction of the upper left corner.
The teeth are actually pillars where new stars may be forming. These structures were formed when radiation and winds from massive stars in a central cluster blew gas and dust away, leaving only the densest of material. The red dots sprinkled throughout the picture are thought to be the youngest stars, still forming in cocoons of dust.
The Pacman nebula, also called NGC 281, is located 9,200 light years away in the constellation Cassiopeia.
A mystery that began nearly 2,000 years ago, when Chinese astronomers witnessed what would turn out to be an exploding star in the sky, has been solved. New infrared observations from NASA’s Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE, reveal how the first supernova ever recorded occurred and how its shattered remains ultimately spread out to great distances.
The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.
“This supernova remnant got really big, really fast,” said Brian J. Williams, an astronomer at North Carolina State University in Raleigh. Williams is lead author of a new study detailing the findings online in the Astrophysical Journal. “It’s two to three times bigger than we would expect for a supernova that was witnessed exploding nearly 2,000 years ago. Now, we’ve been able to finally pinpoint the cause.”
A new image of the supernova, known as RCW 86, is online at http://go.nasa.gov/pnv6Oy .
New observations by NASA’s Wide-field Infrared Survey Explorer, or WISE, show there are significantly fewer near-Earth asteroids in the mid-size range than previously thought. The findings also indicate NASA has found more than 90 percent of the largest near-Earth asteroids, meeting a goal agreed to with Congress in 1998.
Astronomers now estimate there are roughly 19,500 — not 35,000 — mid-size near-Earth asteroids. Scientists say this improved understanding of the population may indicate the hazard to Earth could be somewhat less than previously thought. However, the majority of these mid-size asteroids remain to be discovered. More research also is needed to determine if fewer mid-size objects (between 330 and 3,300-feet wide) also mean fewer potentially hazardous asteroids, those that come closest to Earth.
The results come from the most accurate census to date of near-Earth asteroids, the space rocks that orbit within 120 million miles (195 million kilometers) of the sun into Earth’s orbital vicinity. WISE observed infrared light from those in the middle to large-size category. The survey project, called NEOWISE, is the asteroid-hunting portion of the WISE mission. Study results appear in the Astrophysical Journal.
NASA will hold a news conference at 1 p.m. EDT on Thurs., Sept. 29, to reveal near-Earth asteroid findings and implications for future research. The briefing will take place in the NASA Headquarters James E. Webb Auditorium, located at 300 E St. SW in Washington.
NASA’s Wide-field Infrared Survey Explorer (WISE) mission, launched in December 2009, captured millions of images of galaxies and objects in space. During the news conference, panelists will discuss results from an enhancement of WISE called Near-Earth Object WISE (NEOWISE) that hunted for asteroids.