Friday, May 27, 2011

Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170 degrees Celsius). This led the team of astronomers to speculate the jets may in fact be transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar system, contain the same type of crystals. Comets are born in regions where water is frozen, much colder than the searing temperatures needed to form the crystals, approximately 1,300 degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the crystals is that materials in our young solar system mingled together in a planet-forming disk. In this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, also participated in the study by characterizing the forming star.

"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

Scientists Detect Earth-Equivalent Amount of Water Within the Moon

There is water inside the moon -- so much, in fact, that in some places it rivals the amount of water found within Earth.

The finding from a scientific team including Brown University comes from the first-ever measurements of water in lunar melt inclusions. Those measurements show that some parts of the lunar mantle have as much water as Earth's upper mantle.

Lunar melt inclusions are tiny globules of molten rock trapped within crystals that are found in volcanic glass deposits formed during explosive eruptions. The new finding, published this week in Science Express, shows lunar magma water contents 100 times higher than previous studies have suggested.

The result is the culmination of years of investigation by the team searching for water and other volatiles in volcanic glasses returned by NASA Apollo missions in the late 1960s and early 1970s. In a paper in Nature in 2008, the same team led by Alberto Saal, associate professor of geological sciences at Brown, reported the first evidence for the presence of water and used models to estimate how much water was originally in the magmas before eruption.

"The bottom line," said Saal, an author on the Science Express paper and the principal investigator on the research grants, "is that in 2008, we said the primitive water content in the lunar magmas should be similar to the water content in lavas coming from the Earth's depleted upper mantle. Now, we have proven that is indeed the case."

The new finding got a critical assist from a Brown undergraduate student, Thomas Weinreich, who found the melt inclusions that allowed the team to measure the pre-eruption concentration of water in the magma and to estimate the amount of water in the Moon's interior. In a classic needle-in-the-haystack effort, Weinreich searched through thousands of grains from the famous high-titanium "orange soil" discovered by astronaut Harrison Schmitt during the Apollo 17 mission before finding ten that included melt inclusions.

"It just looks like a clear sample with some black specks in it," said Weinreich, the second author on the paper.

Compared with meteorites, Earth and the other inner planets of our solar system contain relatively low amounts of water and volatile elements, which were not abundant in the inner solar system during planet formation. The even lower quantities of these volatile elements found on the Moon has long been claimed as evidence that it must have formed following a high-temperature, catastrophic giant impact. But this new research shows that aspects of this theory must be reevaluated.

"Water plays a critical role in determining the tectonic behavior of planetary surfaces, the melting point of planetary interiors and the location and eruptive style of planetary volcanoes," said Erik Hauri, a geochemist with the Carnegie Institution of Washington and lead author of the study. "We can conceive of no sample type that would be more important to return to Earth than these volcanic glass samples ejected by explosive volcanism, which have been mapped not only on the moon but throughout the inner solar system."

The research team measured the water content in the inclusions using a state-of-the-art NanoSIMS 50L ion microprobe.

"In contrast to most volcanic deposits, the melt inclusions are encased in crystals that prevent the escape of water and other volatiles during eruption. These samples provide the best window we have on the amount of water in the interior of the Moon," said James Van Orman of Case Western Reserve University, a member of the science team.

The study also puts a new twist on the origin of water ice detected in craters at the lunar poles by several recent NASA missions. The ice has been attributed to comet and meteor impacts, but it is possible some of this ice could have come from the water released by eruption of lunar magmas.

Malcolm Rutherford, professor emeritus in geological sciences at Brown, also contributed to the paper. The NASA LASER and Cosmochemistry programs funded the research, with additional support provided by the NASA Lunar Science Institute (NLSI) and the NASA Astrobiology Institute.

Thursday, May 26, 2011

NASA's Hubble Finds Rare 'Blue Straggler

NASA's Hubble Space Telescope has found a rare class of oddball stars called blue stragglers in the hub of our Milky Way, the first detected within our galaxy's bulge

Blue stragglers are so named because they seemingly lag behind in the aging process, appearing younger than the population from which they formed. While they have been detected in many distant star clusters, and among nearby stars, they never have been seen inside the core of our galaxy.

It is not clear how blue stragglers form. A common theory is that they emerge from binary pairs. As the more massive star evolves and expands, the smaller star gains material from its companion. This stirs up hydrogen fuel and causes the growing star to undergo nuclear fusion at a faster rate. It burns hotter and bluer, like a massive, young star.

The findings support the idea that the Milky Way's central bulge stopped making stars billions of years ago. It now is home to aging sun-like stars and cooler red dwarfs. Giant blue stars that once lived there have long since exploded as supernovae.

The results have been accepted for publication in an upcoming issue of the Astrophysical Journal. Lead author Will Clarkson of Indiana University in Bloomington and the University of California in Los Angeles, will discuss them May 25, 2011 at the American Astronomical Society meeting in Boston.

"Although the Milky Way bulge is by far the closest galaxy bulge, several key aspects of its formation and subsequent evolution remain poorly understood," Clarkson said. "Many details of its star-formation history remain controversial. The extent of the blue straggler population detected provides two new constraints for models of the star-formation history of the bulge."

The discovery followed a seven-day survey in 2006 called the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS). Hubble peered at 180,000 stars in the crowded central bulge of our galaxy, 26,000 light-years away. The survey was intended to find hot Jupiter-class planets that orbit very close to their stars. In doing so, the SWEEPS team also uncovered 42 oddball blue stars with brightness and temperatures typical for stars much younger than ordinary bulge stars.

The observations clearly indicate that if there is a young star population in the bulge, it is very small. It was not detected in the SWEEPS program. Blue stragglers long have been suspected to be living in the bulge, but had not been observed because younger stars in the disk of our galaxy lie along the line-of-sight to the core, confusing and contaminating the view.

Astronomers used Hubble to distinguish the motion of the core population from foreground stars in the Milky Way. Bulge stars orbit the galactic center at a different speed than foreground stars. Plotting their motion required returning to the SWEEPS target region with Hubble two years after the first observations were made. The blue stragglers were identified as moving along with the other stars in the bulge.

"The size of the field of view on the sky is roughly that of the thickness of a human fingernail held at arm's length, and within this region, Hubble sees about a quarter million stars toward the bulge," Clarkson said. "Only the superb image quality and stability of Hubble allowed us to make this measurement in such a crowded field."

From the 42 candidate blue stragglers, the investigators estimate 18 to 37 are likely genuine. The remainder could be a mix of foreground objects and, at most, a small population of genuinely young bulge stars.

"The SWEEPS program was designed to detect transiting planets through small light variations," said Kailash Sahu, the principal investigator of the SWEEPS program. "Therefore the program could easily detect the variability of binary pairs, which was crucial in confirming these are indeed blue stragglers."

Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington. For images and more information about the findings, visit: and

Teasing Apart Galaxy Collisions: Spitzer Photo Atlas of Galactic 'Train Wrecks

 Five billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. This will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars.

To understand our past and imagine our future, we must understand what happens when galaxies collide. But since galaxy collisions take place over millions to billions of years, we can't watch a single collision from start to finish. Instead, we must study a variety of colliding galaxies at different stages. By combining recent data from two space telescopes, astronomers are gaining fresh insights into the collision process.

"We've assembled an atlas of galactic 'train wrecks' from start to finish. This atlas is the first step in reading the story of how galaxies form, grow, and evolve," said lead author Lauranne Lanz of the Harvard-Smithsonian Center for Astrophysics (CfA).

Lanz presented her findings May 25 at the 218th meeting of the American Astronomical Society.

The new images combine observations from NASA's Spitzer Space Telescope, which observes infrared light, and NASA's Galaxy Evolution Explorer (GALEX) spacecraft, which observes ultraviolet light. By analyzing information from different parts of the light spectrum, scientists can learn much more than from a single wavelength alone, because different components of a galaxy are highlighted.

GALEX's ultraviolet data captures the emission from hot young stars. Spitzer sees the infrared emission from warm dust heated by those stars, as well as from stellar surfaces. Therefore, GALEX's ultraviolet data and Spitzer's infrared data highlight areas where stars are forming most rapidly, and together permit a more complete census of the new stars.

In general, galaxy collisions spark star formation. However, some interacting galaxies produce fewer new stars than others. Lanz and her colleagues want to figure out what differences in physical processes cause these varying outcomes. Their findings will also help guide computer simulations of galaxy collisions.

"We're working with the theorists to give our understanding a reality check," said Lanz. "Our understanding will really be tested in five billion years, when the Milky Way experiences its own collision."

Lanz's co-authors are Nicola Brassington (Univ. of Hertfordshire, UK); Andreas Zezas (Univ. of Crete, Greece, and CfA); Howard Smith and Matt Ashby (CfA); Christopher Klein (UC Berkeley); and Patrik Jonsson, Lars Hernquist, and Giovanni Fazio (CfA).

Carrying Humans Into Deep Space: NASA Announces Key Decision for Next Deep Space Transportation System

NASA has reached an important milestone for the next U.S. transportation system that will carry humans into deep space. NASA Administrator Charles Bolden announced May 25, 2011 that the system will be based on designs originally planned for the Orion Crew Exploration Vehicle. Those plans now will be used to develop a new spacecraft known as the Multi-Purpose Crew Vehicle (MPCV).

"We are committed to human exploration beyond low-Earth orbit and look forward to developing the next generation of systems to take us there," Bolden said. "The NASA Authorization Act lays out a clear path forward for us by handing off transportation to the International Space Station to our private sector partners, so we can focus on deep space exploration. As we aggressively continue our work on a heavy lift launch vehicle, we are moving forward with an existing contract to keep development of our new crew vehicle on track."

Lockheed Martin Corp. will continue working to develop the MPCV. The spacecraft will carry four astronauts for 21-day missions and be able to land in the Pacific Ocean off the California coast. The spacecraft will have a pressurized volume of 690 cubic feet, with 316 cubic feet of habitable space. It is designed to be 10 times safer during ascent and entry than its predecessor, the space shuttle.

"This selection does not indicate a business as usual mentality for NASA programs," said Douglas Cooke, associate administrator for the agency's Exploration Systems Mission Directorate in Washington. "The Orion government and industry team has shown exceptional creativity in finding ways to keep costs down through management techniques, technical solutions and innovation."

Kepler's Astounding Haul of Multiple-Planet Systems

NASA's Kepler spacecraft is proving itself to be a prolific planet hunter. Within just the first four months of data, astronomers have found evidence for more than 1,200 planetary candidates. Of those, 408 reside in systems containing two or more planets, and most of those look very different than our solar system.

In particular, the Kepler systems with multiple planets are much flatter than our solar system. They have to be for Kepler to spot them. Kepler watches for a planet to cross in front of its star, blocking a tiny fraction of the star's light. By measuring how much the star dims during such a transit, astronomers can calculate the planet's size, and by observing the time between successive events they can derive the orbital period -- how long it takes the planet to revolve around its star.

To see a transit, the planet's orbit must be edge-on to our line of sight. To see multiple transiting planets, they all must be edge-on (or nearly so).

"We didn't anticipate that we would find so many multiple-transit systems. We thought we might see two or three. Instead, we found more than 100," said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics).

Latham presented the findings May 24 in a press conference at the 218th meeting of the American Astronomical Society.

In our solar system, some planet orbits are tilted by up to 7 degrees, meaning that an alien astronomer looking for transits wouldn't be able to detect all eight planets. (In particular, they would miss Mercury and Venus.) The systems spotted by Kepler are much flatter, with orbits tilted less than 1 degree.

Why are they so flat? One clue comes from the planets themselves. The multiplanet systems found by Kepler are dominated by planets smaller than Neptune. They lack Jupiter-sized gas giants. Scientists believe that a gas giant's powerful gravity tends to disrupt planetary systems, tilting the orbits of neighboring worlds.

"Jupiters are the 800-pound gorillas stirring things up during the early history of these systems," explained Latham. "Other studies have found plenty of systems with big planets, but they're not flat."

Multiple-planet systems may offer a chance for confirming the densities of small, rocky worlds. The more massive a planet, the easier it is to detect using radial velocity measurements (essentially the star's wobble as a planet's gravity tugs it). Earth-sized worlds in Earth-sized orbits aren't massive enough to make a radial velocity signal that's detectable with present technology.

In systems with more than one transiting planet, astronomers have another option: transit timing variations. They can measure how the time between successive transits changes from orbit to orbit due to mutual gravitational interactions between the planets. The size of the effect depends on the planets' masses.

"These planets are pulling and pushing on each other, and we can measure that," said Smithsonian astronomer Matthew Holman. "Dozens of the systems Kepler found show signs of transit timing variations."

As Kepler continues to gather data, it will be able to spot planets with wider orbits, including some in the habitable zones of their stars. Transit timing variations may play a key role in confirming the first rocky planets with the right temperature for water to be liquid on their surfaces.

NASA Ames Research Center is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system, and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data.

Friday, May 13, 2011

Johannes Kepler

Johannes Kepler was born on December 27, 1571, a premature child. To be precise, according to his own records, the pregnancy lasted 224 days, 9 hours and 53 minutes. (This rather odd piece of information, and the quotes from Kepler's horoscopes for his family given below, I found in Koestler's book, reference 1.) It should be clear from this obsession with the precise time of birth and conception that Kepler took astrology fairly seriously. He was born in Weil, in Swabia, a wine region in southwest Germany not far from France. Unfortunately, the family he was born into makes Tycho's early life look tranquil by comparison. Kepler's grandfather was Mayor of Weil, Kepler describes his grandmother as "restless, clever and lying, but devoted to religion; slim and of a fiery nature; vivacious, an inveterate troublemaker; jealous, extreme in her hatreds, violent, a bearer of grudges...and all her children have something of this". His father he describes as "...a man vicious, inflexible, quarrelsome and doomed to a bad end. Venus and Mars increase his malice. Saturn in VII made him study gunnery..." Kepler's mother he describes in the family horoscope as "small, thin, swarthy, gossiping and quarrelsome, of a bad disposition". His mother collected herbs and made potions which she believed had magical powers. She was raised by an aunt who was burned at the stake as a witch, and Kepler's mother narrowly escaped a similar fate herself (see ref 2, page 159: Kepler had to hire several lawyers to defend his seventy-year-old mother incarcerated on a charge of witchcraft, and "Another woman born in the same town as Kepler's mother, and accused of complicity with her, had already left one of her thumbs stuck in the rack".)

As a seven-month child, Kepler was sickly from birth, and contracted smallpox when very young. His vision was severely defective, and he had various other illnesses fairly constantly, some of which may have been hypochondria. He took twice as long as normal children to get through elementary latin. He did a little better when he got to the higher school at Maulbronn, a school which only half a century earlier was haunted by the ill-famed Dr. Faustus (ref 2).

Kepler went to the University of Tuebingen, a Protestant institution, where he studied mainly theology and philosophy, but also mathematics and astronomy. (The Dukes of Wuerttemberg, after becoming Lutheran, put in place an efficient educational system, with grants and scholarships for the poor, to ensure the universities could supply well educated clergymen capable of defending the new faith in the religious controversies raging at the time.) At the university, Kepler's exceptional intellectual abilities became apparent. He greatly admired the astronomy professor Maestlin, who publicly taught the Ptolemaic scheme, but privately believed Copernicus. Kepler himself defended Copernicus' scheme in a public debate. Unfortunately for him, that ensured that he would not be offered a faculty position at Tuebingen when he graduated. (Luther himself had mocked at Copernicus' scheme, and quoted scripture to prove it wrong.) Instead, Kepler was offered a professorship of astronomy in faraway Graz, Styria (now part of Austria), where he went in 1594. One of the duties of this professorship was to make astrological predictions. Despite his earlier efforts at horoscopes, he wrote "a mind accustomed to mathematical deduction, when confronted with the faulty foundations (of astrology) resists a long, long time, like an obstinate mule, until compelled by beating and curses to put its foot into that dirty puddle" (ref 1, page 245). Nevertheless, he predicted a cold winter, and an invasion by the Turks. Both predictions turned out to be correct. He was treated with a new respect, and his salary was increased.