October 31, 2006, 6:48 PM CT

Esperanza Fire

Smoke from the Esperanza Fire washed over the mountains southeast of Los Angeles and over the Pacific Ocean.
Waves of gray-brown smoke washed over the mountains southeast of Los Angeles and out over the Pacific on Oct. 26, 2006, on the same day on which four firefighters were killed fighting the blaze. West of Palm Springs, Calif., the Esperanza Fire had ballooned under the influence of Santa Ana winds to encompass more than 19,000 acres as of the morning of Oct. 27, as per the daily report from the National Interagency Fire Center. Racing through grass, brush, and timber, the blaze had forced hundreds to evacuate, and it killed several firefighters who were working to protect homes. Fire officials are reporting the cause of the blaze as arson.

This photo-like image shows the fire and surrounding area captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite on Oct. 26. Places where MODIS detected actively burning fire are outlined in red. The Santa Ana Mountains peak out from beneath the smoke near the southeastern suburbs of Los Angeles.

Santa Ana winds are a California firefighter's nightmare. These blustery, dry and often hot winds blow out of the desert and race through canyons and passes in the mountains on their way toward the coast. The air is hot not because it is bringing heat from the desert, but because it is flowing downslope from higher elevations. As fall progresses, cold air begins to sink into the Great Basin deserts to the east of California. As the air piles up at the surface, high pressure builds, and the air begins to flow downslope toward the coast. When winds blow downslope, the air gets compressed, which causes it to warm and dry out. In fact, the air can warm at a rate of 10 degrees Celsius per kilometer of descent (29 degrees Fahrenheit per mile). Canyons and passes funnel the winds, which increases their speed. Not only do the winds spread the fire, but they also dry out vegetation, making it even more flammable.........

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October 31, 2006, 6:43 PM CT

Crab Nebula

Credit: NASA - X-ray: CXC, J.Hester (ASU) et al
The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from the death explosion of a massive star. This intriguing false-color image combines data from space-based observatories, Chandra, Hubble, and Spitzer, to explore the debris cloud in x-rays (blue-purple), optical (green), and infrared (red) light.

One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away in the constellation Taurus.........

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October 31, 2006, 6:38 PM CT

Halloween For Nebula

The dark nebula SH2-136 appears to be celebrating Halloween all of the time. The complex process of star formation create dust clouds of a number of shapes and sizes -- it is human perception that might identify a ghoulish creature, on the right of the above image, chasing humans.

Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week. Other cross-quarter markers include Groundhog Day and Walpurgis Night.........

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October 27, 2006, 5:04 AM CT

Latest views of the V838

Hubble has returned to the intriguing V838 Monocerotis a number of times since its initial outburst in 2002 to follow the evolution of its light echo. Two new images provide the most astonishing views of V838 to date.

The unusual variable star V838 Monocerotis (V838 Mon) continues to puzzle astronomers. This previously inconspicuous star underwent an outburst early in 2002, during which it temporarily increased in brightness to become 600,000 times more luminous than our Sun. Light from this sudden eruption is illuminating the interstellar dust surrounding the star, producing the most spectacular "light echo" in the history of astronomy.

As light from the eruption propagates outward into the dust, it is scattered by the dust and travels to the Earth. The scattered light has travelled an extra distance compared to light that reaches Earth directly from the stellar outburst. Such a light echo is the optical analogue of the sound echo produced when an Alpine yodel is reflected from the surrounding mountainsides.

The NASA/ESA Hubble Space Telescope has been observing the V838 Mon light echo since 2002. Each new observation of the light echo reveals a new and unique "thin-section" through the interstellar dust around the star. This release shows new images of the light echo from the Hubble Advanced Camera for Surveys taken in November 2005 (left) and again in September 2006 (right). The numerous whorls and eddies in the interstellar dust are especially noticeable. Possibly they have been produced by the effects of magnetic fields in the space between the stars.........

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October 27, 2006, 4:32 AM CT

Cracking The Stellar Evolution

Using 3D models run on some of the fastest computers in the world, Laboratory physicists have created a mathematical code that cracks a mystery surrounding stellar evolution.

For years, physicists have theorized that low-mass stars (about one to two times the size of our sun) produce great amounts of helium 3 (³He). When they exhaust the hydrogen in their cores to become red giants, most of their makeup is ejected, substantially enriching the universe in this light isotope of helium.

This enrichment conflicts with the Big Bang predictions. Researchers theorized that stars destroy this ³He by assuming that nearly all stars were rapidly rotating, but even this failed to bring the evolution results into agreement with the Big Bang.

Now, by modeling a red giant with a fully 3D hydrodynamic code, LLNL scientists identified the mechanism of how and where low-mass stars destroy the ³He that they produce during evolution.

They observed that ³He burning in a region just outside of the helium core, previously believed to be stable, creates conditions that drive this newly discovered mixing mechanism.

Bubbles of material, slightly enriched in hydrogen and substantially depleted in ³He, float to the surface of the star and are replaced by ³He-rich material for additional burning. In this way the stars destroy their excess ³He, without assuming any additional conditions (like rapid rotation).........

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October 26, 2006, 5:04 AM CT

200-million-year-old Baby Galaxies

Astronomers have taken amazing pictures of two of the most distant galaxies ever seen. The ultradeep images, taken at infrared wavelengths, confirm for the first time that these celestial cherubs are real. The researchers* are now able to weigh galaxies and determine their age at earlier times than ever before, providing important clues about the evolutionary origins of galaxies like our Milky Way. The work appears in the October 1 issue of Astrophysical Journal Letters.

Carnegie Fellow Ivo Labbe, along with Rychard Bouwens and Garth Illingworth of the UCO/Lick Observatory at the University of California, Santa Cruz, and Marijn Franx of the Leiden Observatory, examined galaxies in the Hubble Ultra Deep Field (HUDF) using the sensitive Infrared Array Camera (IRAC) aboard NASA's Spitzer Space Telescope. The HUDF, scanned by NASA's Hubble Space Telescope in late 2003, remains the deepest view ever taken at visible and near-infrared wavelengths.

The two galaxies are seen when the universe was just a baby-700 million years after the Big Bang, or five percent of the universe's current age. They belong to a precious small sample of similarly ancient galaxies, discovered two years ago by Bouwens, Illingworth, and Franx and analyzed in-depth in Nature last month. The relative deficit of such far-away luminous sources indicates that this early period is when galaxies were rapidly building up from a very small number of stars to the massive galaxies we see at later times.........

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October 24, 2006, 8:31 PM CT

Direct Proof Of Stellar Sorting In A Globular Cluster

A seven year study with the NASA/ESA Hubble Space Telescope has provided astronomers with the best observational evidence yet that globular clusters sort out stars as per their mass, governed by a gravitational billiard ball game between stars. Heavier stars slow down and sink to the cluster's core, while lighter stars pick up speed and move across the cluster to its periphery. This process, called "mass segregation", has long been suspected for globular star clusters, but has never before been directly seen in action.

Imagine trying to understand how a football game works based on just a few fuzzy snapshots of the game in play. This is the just the kind of challenge faced by astronomers trying to understand the dynamics of the swarm of stars in the globular star clusters that orbit our Milky Way Galaxy. The NASA/ESA Hubble Space Telescope has provided the best observational evidence to date that globular clusters sort stars as per their mass, governed by a gravitational billiard ball game between stars. Heavier stars slow down and sink to the cluster's core, while lighter stars pick up speed and move out across the cluster to its periphery. This process, called mass segregation, has long been suspected for globular star clusters, but has never been seen in action directly before.........

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October 16, 2006, 9:30 PM CT

New Details of Mars, Young and Old

During its first week of observations from low orbit, NASA's newest Mars spacecraft is already revealing new clues about both recent and ancient environments on the red planet.

Researchers hope the Mars Reconnaissance Orbiter will answer questions about the history and distribution of Mars' water by combining data from the orbiter's high-resolution camera, imaging spectrometer, context camera, ground-penetrating radar, atmospheric sounder, global color camera, radio and accelerometers.

Between Sept. 29 and Oct. 6, science instruments on the spacecraft viewed dozens of sites that reflect different episodes in Mars' history. The diverse sites provide a good test for the capabilities of the spacecraft instruments. The orbiter will begin its primary science mission phase in early November when Mars re-emerges from passing nearly behind the sun.

The instruments are seeing details in the shapes and icy composition of geologically young layering near the Martian north pole. Other views offer details of a mid-latitude valley whose upper layers have been eroded away, revealing an underlying clay layer that formed a few billion years ago, when wet conditions produced the clay. Observations of a southern-hemisphere crater show fine-scale details of more recent gullies, adding evidence that they were carved by flowing water.........

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October 15, 2006, 8:41 PM CT

Complex Meteorology At Venus

In its relentless probing of Venus's atmosphere, ESA's Venus Express keeps revealing new details of the Venusian cloud system. Meteorology at Venus is a complex matter, scientists say.

New night-side infrared images gathered by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) in July 2006, clearly show new details of a complex cloud system.

The first (false colour) view - the composite of three infrared images acquired by VIRTIS, was taken on 22 July when the spacecraft was flying around the apocentre of its orbit (point of maximum distance from the planet surface) at about 65 000 kilometres altitude. Venus was in the night side.

Using its capability to observe at 1.7-micrometre wavelenght, VIRTIS could probe at about 15-20 kilometres altitude, below the thick cloud deck situated at about 60 kilometres from the surface. The thermal radiation coming from the oven-hot surface of Venus is represented by the intensity of the colours: the brighter the colour (towards white), the more radiation comes from the surface, so the less cloudy the region in the line of sight between the view and the spacecraft is.

The edge of the images, taken at a time interval of about 30 minutes from each other, do not precisely match. This is due to the fact that clouds on Venus move very rapidly and constantly vary their shape. Venus's atmosphere is certainly the most dynamic among the terrestrial planets that have one, taking only four days to completely rotate around the planet.........

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October 12, 2006, 8:25 PM CT

Mug Shots Of Supernovas

Researchers using NASA's Swift satellite have observed two dozen recent star explosions, called supernovae, quickly after the event and have discovered never-before-seen properties, some of which run counter to prevailing theories.

In one observation, they have confirmed the origin of Type Ia supernovae, an important class of explosions used to measure distances and dark energy. In other observations they have found new mechanisms to produce X-rays and ultraviolet light.

The findings have emerged from a concerted effort by the Swift team to capture images of ordinary supernovae as rapidly as possible. Stefan Immler of NASA's Goddard Space Flight Center, Greenbelt, Md., led the analysis of these supernovae.

For a number of supernovae, we are getting to the scene of the crime to investigate the explosion within hours to days, as opposed to the typical delay time of days to weeks," said Immler. "We are finding clues about how stars explode that would have disappeared had we turned our telescopes to the site just a few days later".

Swift's primary goal to study gamma-ray bursts, the most energetic explosions in the universe. Most gamma-ray bursts last no longer than about ten seconds, so speed is essential to detect and study the bursts. Swift has three telescopes: A gamma-ray telescope to detect the burst, and X-ray and ultraviolet/optical telescopes to provide rapid follow-up observations, all the while broadcasting the burst location to other observatories.........

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