The Coolest Stars Come Out of the Dark

Astronomers have uncovered what appear to be 14 of the coldest stars known in our universe. These failed stars, called brown dwarfs, are so cold and faint that they'd be impossible to see with current visible-light telescopes. Spitzer's infrared vision was able to pick out their feeble glow, much as a firefighter uses infrared goggles to find hot spots buried underneath a dark forest floor.

The brown dwarfs join only a handful of similar objects previously discovered. The new objects are between the temperatures of about 450 Kelvin to 600 Kelvin (350 to 620 degrees Fahrenheit). As far as stars go, this is bitter cold -- as cold, in some cases, as planets around other stars.

These cool orbs have remained elusive for years, but will soon start coming out of the dark in droves. NASA's Wide-field Infrared Survey Explorer (WISE) mission, which is up scanning the entire sky now in infrared wavelengths, is expected to find hundreds of objects of a similarly chilly disposition, if not even colder. WISE is searching a volume of space 40 times larger than that sampled in the recent Spitzer study, which concentrated on a region in the constellation Boötes. The Spitzer mission is designed to look at targeted patches of sky in detail, while WISE is combing the whole sky.

"WISE is looking everywhere, so the coolest brown dwarfs are going to pop up all around us," said Peter Eisenhardt, the WISE project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and lead author of a recent paper in the Astronomical Journal on the Spitzer discoveries. "We might even find a cool brown dwarf that is closer to us than Proxima Centauri, the closest known star."

Brown dwarfs form like stars out of collapsing balls of gas and dust, but they are puny in comparison, never collecting enough mass to ignite nuclear fusion and shine with starlight. The smallest known brown dwarfs are about 5 to 10 times the mass of our planet Jupiter -- that's as massive as some known gas-giant planets around other stars. Brown dwarfs start out with a bit of internal heat left over from their formation, but with age, they cool down. The first confirmed brown dwarf was announced in 1995.

"Brown dwarfs are like planets in some ways, but they are in isolation," said astronomer Daniel Stern, co-author of the Spitzer paper at JPL. "This makes them exciting for astronomers -- they are the perfect laboratories to study bodies with planetary masses."

Most of the new brown dwarfs found by Spitzer are thought to belong to the coolest known class of brown dwarfs, called T dwarfs, which are defined as being less than about 1,500 Kelvin (2,240 degrees Fahrenheit). One of the objects appears to be so cold that it may even be a long-sought Y dwarf -- a proposed class of even colder stars. The T and Y classes are part of a larger system categorizing all stars; for example, the hottest, most massive stars are O stars; our sun is a G star.

"Models indicate there may be an entirely new class of stars out there, the Y dwarfs, that we haven't found yet," said co-author Davy Kirkpatrick, a co-author of the study and a member of the WISE science team at the California Institute of Technology, Pasadena, Calif. "If these elusive objects do exist, WISE will find them." Kirkpatrick is a world expert in brown dwarfs -- he came up with L, T and Y classifications for the cooler stars.

Kirkpatrick says that it's possible that WISE could find an icy, Neptune-sized or bigger object in the far reaches of our solar system -- thousands of times farther from the sun than Earth. There is some speculation amongst scientists that such a cool body, if it exists, could be a brown dwarf companion to our sun. This hypothetical object has been nicknamed "Nemesis."

"We are now calling the hypothetical brown dwarf Tyche instead, after the benevolent counterpart to Nemesis," said Kirkpatrick. "Although there is only limited evidence to suggest a large body in a wide, stable orbit around the sun, WISE should be able to find it, or rule it out altogether."

The 14 objects found by Spitzer are hundreds of light-years away -- too far away and faint for ground-based telescopes to see and confirm with a method called spectroscopy. But their presence implies that there are a hundred or more within only 25 light-years of our sun. Because WISE is looking everywhere, it will find these missing orbs, which will be close enough to confirm with spectroscopy. It's possible that WISE will even find more brown dwarfs within 25-light years of the sun than the number of stars known to exist in this space.

"WISE is going to transform our view of the solar neighborhood," said Eisenhardt. We'll be studying these new neighbors in minute detail -- they may contain the nearest planetary system to our own."
Other authors of the Spitzer paper are Roger Griffith and Amy Mainzer of JPL; Ned Wright, A.M. Ghez and Quinn Konopacky of UCLA; Matthew Ashby and Mark Brodwin of the Harvard-Smithsonian Center for Astrophysics, Cambridge; Mass., Michael Brown of Monash University, Australia; R.S. Bussmann of the University of Arizona, Tucson; Arjun Dey of National Optical Astronomy Observatory, Tucson, Ariz.; Eilat Glikman of Caltech; Anthony Gonzalez and David Vollbach of the University of Florida, Gainesville; and Shelley Wright of the University of California, Berkeley.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.
JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer. More information about WISE is online at http://wise.astro.ucla.edu/ and http://www.nasa.gov/wise.





Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

Yeremiah Hardt

yeremiah@aol.com

Poisonous Superstorm found on Alien World

By Clara Moskowitz


SPACE.com Senior Writer

posted: 23 June 2010

01:06 pm ET

Across the Milky Way lies a violent world with the first "superstorm" ever spotted on an alien planet.

Poisonous carbon monoxide gas is streaming at enormous speeds from the extremely hot day side to the cooler night side of the exoplanet, new observations show. This hot, gaseous Jupiter-like world is dubbed HD209458b, and lies about 150 light-years from Earth toward the constellation Pegasus.

"HD209458b is definitely not a place for the faint-hearted," said lead researcher Ignas Snellen of Leiden Observatory in the Netherlands. "By studying the poisonous carbon monoxide gas with great accuracy we found evidence for a super wind, blowing at a speed of 5,000 to 10,000 km per hour [3,100 to 6,200 mph]."

The new study, of a world first discovered in 1999, also enabled the astronomers to measure the planet's mass for the first time from calculations of its velocity. The researchers obtained new high-resolution views of the exoplanet using the European Southern Observatory's Very Large Telescope in Chile. [The Strangest Alien Planets]

Alien superstorm

HD209458b has about 60 percent the mass of Jupiter, yet orbits its star only one-twentieth the distance between the sun and Earth, which are separated by about 93 million miles (150 million km). These close quarters give the planet surface temperatures around 1,830 degrees Fahrenheit (1,000 degrees Celsius) on the hot side.

The researchers think radiation from the star is driving the strong winds and storms.

The tiny orbit also keeps one side of the world permanently facing its star – and thus very hot – while the dark side perpetually faces outward and is frigid.

"On Earth, big temperature differences inevitably lead to fierce winds, and as our new measurements reveal, the situation is no different on HD209458b," said co-researcher Simon Albrecht of MIT.

Exoplanet transit

To learn about HD209458b, the astronomers observed it as it passed in front of its host star – a process that recurs every 3.5 days and is known as a transit. When this happens, the planet blocks most of the star's light, though a small fraction filters through the planet's atmosphere, which leaves an imprint on the light.

The researchers analyzed the faint fingerprints left by carbon monoxide to determine how fast the gas was moving on the surface of the planet. They could do this thanks to a phenomenon called the Doppler effect, which describes how light or sound waves will shift in frequency when their source moves.

The changes in Doppler shift over time also allowed the astronomers to calculate the velocity of the exoplanet as it moves around its star, which in turn enabled them to deduce its mass.

"In general, the mass of an exoplanet is determined by measuring the wobble of the star and assuming a mass for the star, according to theory," said co-researcher Ernst de Mooij. "Here, we have been able to measure the motion of the planet as well, and thus determine both the mass of the star and of the planet."

Previous studies of this planet also detected the basic molecules required for life in its atmosphere. The chemicals, including water, methane and carbon dioxide, are promising signs in the hunt for life beyond Earth, though no evidence has yet been found for extraterrestrials on HD209458b or anywhere in the universe.

The new observations provided more detail on the presence of carbon on the world.

"It seems that H209458b is actually as carbon-rich as Jupiter and Saturn," Snellen said. "This could indicate that it was formed in the same way. In the future, astronomers may be able to use this type of observation to study the atmospheres of Earth-like planets, to determine whether life also exists elsewhere in the Universe."

Yeremiah Hardt
yeremiah@aol.com

Matter of Perspective

The Seagull nebula, seen in this infrared mosaic from NASA's Wide-field Infrared Survey Explorer, or WISE, draws its common name from it resemblance to a gull in flight. But it depends on your point of view. When the image is rotated 180 degrees it bears a passing resemblance to a galloping lizard -- or perhaps a dragon or a dinosaur. The image spans an area about seven times as wide as the full moon, and three times as high (3.55 by 1.37 degrees), straddling the border between the constellations Monoceros and Canis Major (the Big Dog). So you might say this lizard is running with the Big Dog, while the gull is flying from it.
Astronomers catalog the nebula as IC 2177. This cosmic cloud is one of many sites of star formation within the Milky Way galaxy. It is located 3,800 light-years away from Earth, inside the Orion spur -- the same partial spiral arm of the Milky Way where our solar system is located. The nebula is nearly 240 light-years across.

WISE is an all-sky survey, snapping pictures of the whole sky -- from asteroids to stars to powerful, distant galaxies.

Yeremiah Hardt
yeremiah@aol.com

Spectacular Space Bubble Photographed by Hubble

A spectacular new photo from the Hubble Space Telescope has revealed a stunning space bubble filled with baby stars.


The new space bubble image highlights an area called N11 – a complex network of gas clouds and star clusters within our neighboring galaxy, the Large Magellanic Cloud.

This energetic star-forming region is the second largest known to date, and one of the most active in our galactic neighbor.

Bubbles in space

The Large Magellanic Cloud contains many bright nebula bubbles, though N11 is one of the most magnificent, Hubble officials said.

Astronomers took the new N11 photo using Hubble's Advanced Camera for Surveys, which was repaired in May 2009 during NASA's last service call to the iconic space telescope. The image is actually a mosaic of five different views observed by Hubble, researchers said.

Officially known as LHA 120-N 11, N11 is one of many nebulas catalogued in 1956 by American astronomer Karl Henize, who later became a NASA astronaut. The object's characteristic shape earned it a nickname as the "Bean Nebula."

N11's billowing pink clouds of glowing gas and the dramatic and colorful features visible in the burgeoning nebula are telltale signs of star-formation. The nebula is a well-studied patch of space that is spread across more than 1,000 light-years and has produced some of the most massive stars currently known.

That star-formation bonanza actually holds the key to the N11 nebula's gossamer bubble look.

Three successive generations of stars, each forming further away from N11's center than the last, have created shells of gas and dust that were later blown away from their parent stars. This created the dazzling ring shapes that are so prominent in the Hubble image.

Star nurseries up close

Other shapes that are found in the high-resolution image include the red bloom of a different nebula – called LHA 120-N 11A – in the upper left. The rose-like petals of gas and dust in this nebula are illuminated by radiation from the massive hot stars at its center.

N11A is relatively compact and dense, and is home to some of the most recent star development in the region.

Other star clusters, including NGC 1761 at the bottom of the image, can also be spotted. NGC 1761 encompasses a group of massive hot, young stars that emit intense ultraviolet radiation out into the cosmos.

By studying these busy stellar nurseries, astronomers can understand more about how stars are born and the details of their ultimate development and lifespan.

• Images - 20 Years of the Hubble Space Telescope

• The 10 Most Amazing Hubble Discoveries

• Why Are Space Telescopes Better Than Earth-Based Telescopes?

Space Quiz

CONSTELLATION :
1.Define constellation.

2.How many constellations are there in the sky?

3.Name the largest constellation by area.

4.Name the brightest star in both northern and southern hemisphere.

5.Name the constellation which divides the northern and southern hemisphere.
DISCOVERY :
1.Who discovered the planet Saturn?

2.Who named the planet Pluto as "Pluto"?

3.Who was the first person suggested that Saturn was surrounded by a ring?

4.Who estimated the radius of VY CANIS MAJORIS as 1,800 to 2,100 solar radii?

5.Who first found the great red spot on the JUPITER ?
ANSWERS:

CONSTELLATIONS:
1. A constellation is a group of celestial bodies, usually stars, which appear to form a pattern in the sky.

A constellation is an internationally defined area of the celestial sphere.

2. It is said to be 88 , but still new constellations are discovered , so it may go about a 150.

3. HYDRA .

AREA : ( SQ.DEG) : 1302.844

4. NORTH : POLARIS

SOUTH : SIRIUS

5. ORIONS

DISCOVERY :
1. In 1610 , Galileo discovered Saturn.

2. VENETIA BURNEY ( NOW Venetia Phair)

3. In 1655, Christiaan huygens

4. professor Roberta.m.Humphreys of UNIVERSITY OF MINNESOTA.

5. ROBERT HOOKE IN 1664

Flashback: Water on Mars Announced 10 Years Ago

By Charles Q. Choi

SPACE.com Contributor

posted: 22 June 2010

08:05 am ET

Ten years ago this week, news from Mars made a huge splash on Earth — water might still flow on the surface of the red planet. That news, announced by NASA, hinged on photos of newfound gullies etched across the Martian surface, and a decade of other water-on-Mars discoveries ensued. Yet even 10 years later definitive proof of flowing Mars water remains elusive.

The quest to find evidence of liquid water on Mars, and the surprises that have turned up along the way, have transformed our view of the red planet from a dry and dead planet to one where life might have flourished and even live still.

"We are definitely on the path to exploring the habitability of Mars — what it's been like in the past and even potentially now," said Michael Meyer, lead scientist for NASA's Mars Exploration Program. [Photos: Water on Mars imagined.]

The big news

Scientists analyzing data from NASA's Mars Global Surveyor spacecraft 10 years ago found what appeared to be gullies formed by flowing water, as well as debris and mud deposits these flows may have left behind.

These features appeared so fresh that they might still be forming today, researchers said at the time. The changing appearance of gullies on Mars over time supported their findings, they later said.

NASA announced the news on June 22, 2000, with the research later appearing in that year's June 30 issue of the journal Science.

There is plenty of evidence that water formed vast oceans in the distant past on Mars, carving valleys and other features that are clearly apparent on its surface.

However, the possibility of liquid water on the red planet's surface today is perplexing, because it cannot survive there due to sub-zero temperatures and the thin Martian atmosphere. As such, the possibility of flowing water on the surface of Mars has been highly debated.

For instance, last year researchers suggested globs of salty water were seen on the legs of NASA's Phoenix Mars Lander. But others on the same team countered that the spots may have been frost instead.

There was no doubt that water ice was present at near the Phoenix lander – which set down in the Martian arctic. In fact, water ice has been found on Mars at the planet's poles, inside some craters and sitting beneath the surface across vast swaths of the Martian mid-latitude regions. But questions still remain on when water last flowed on the red planet's surface.

"There's been no smoking gun evidence yet as to whether liquid water has been on the surface of Mars in the recent past," Meyer said.

Challenging search

One of the main problems about proving whether or not water still flows on the surface of Mars "is that where we have seen gullies also tends to be where we don't want to land spacecraft," Meyer explained.

"The hope is that orbiter missions can catch something in the act involving liquid water near the surface today," he said. "We do suspect there's liquid water in the subsurface — it's just depends on how deep you have to go."

Europe's Mars Express spacecraft has been probing for hidden pockets of ice and liquid water using ground-penetrating radar. NASA's powerful Mars Reconnaissance Orbiter has also been searching for evidence of Mars' watery past from orbit.

One thing has become certain over the past decade: There was once a lot of water on Mars, and much frozen water remains hidden there.

"We've gone from suspecting there was water on Mars once upon a time to deciding there definitely was water, and not only that there was water, but lots of water," Meyer said. "Now with the Mars Reconnaissance Orbiter, we've found frozen water even at mid-latitudes, so the inventory of water on Mars is looking better and better as we learn more."

The excitement concerning water on Mars is rooted in how central we know water is to life on Earth.

"How much water has been on Mars, how long we think it was there and how many places might have had it makes a difference in how habitable we think it might have been," Meyer said.

Although research continues to look at water on Mars, "in many ways we are moving beyond specifically looking for water on Mars and more at what the consequences of water might be — for example, minerals formed in the presence of water, particularly maybe organic matter, which might have preserved what went on in early Mars," Meyer said. And, of course, the whole effort is aimed at determining whether life ever did, or does, exist on Mars.

"Currently we're holding landing site workshops for the Mars Science Laboratory, which is set to launch next year, for specific places to go to look at such minerals," he added.

Twenty Years of Hubble

Twenty years after its April 24, 1990 launch, the Hubble Space Telescope is an icon in space. Here are some of the most amazing views from the prolific space telescope. Hubble’s new Wide Field Camera 3 (WFC3) starts things off in this image of the planetary nebula, cataloged as NGC 6302, but more popularly called the Bug Nebula or the Butterfly Nebula. WFC3 was installed by NASA astronauts in May 2009, during the servicing mission to upgrade and repair the 19-year-old Hubble telescope. Click to enlarge.

Cosmic Dust Cloud
A recent NASA/ESA Hubble Space Telescope close-up image of part of NGC 7023, or the Iris Nebula, shows that the area is clogged with cosmic dust. This image was taken after the May 2009 shuttle mission to overhaul Hubble for the final time.

Beautiful Barred Spiral Galaxy
One of the largest Hubble Space Telescope images ever made of a complete galaxy was unveiled at the American Astronomical Society meeting in San Diego, Calif. The Hubble telescope captured a display of starlight, glowing gas, and silhouetted dark clouds of interstellar dust in this 4-foot-by-8-foot image of the barred spiral galaxy NGC 1300. r Stellar Outburst

The Hubble Space Telescope’s latest image of the star V838 Monocerotis (V838 Mon) reveals dramatic changes in the illumination of surrounding dusty cloud structures. The effect, called a light echo, has been unveiling never-before-seen dust patterns ever since the star suddenly brightened for several weeks in early 2002.

Auroras on Saturn
The dancing light of the auroras on Saturn behaves in ways different from how scientists have thought possible for the last 25 years. New research by a team of astronomers led by John Clarke of Boston University has overturned theories about how Saturn’s magnetic field behaves and how its auroras are generated.

 
The Eagle Has Risen: Stellar Spire in the Eagle Nebula
NASA released this new image to commemorate the 15th anniversary of the Hubble Telescope. Appearing like a winged fairy-tale creature poised on a pedestal, this object is actually a billowing tower of cold gas and dust rising from a stellar nursery called the Eagle Nebula. The soaring tower is 9.5 light-years or about 57 trillion miles high, about twice the distance from our Sun to the next nearest star

 
Boomerang Nebula
NASA’s Hubble Space Telescope caught the Boomerang Nebula in images taken with the Advanced Camera for Surveys in early 2005. This reflecting cloud of dust and gas has two nearly symmetric lobes of matter that are being ejected from a central star. Each lobe of the nebula is nearly one light-year in length, making the total length of the nebula half as long as the distance from our Sun to our nearest neighbors- the Alpha Centauri stellar system, located roughly 4 light-years away. The Boomerang Nebula resides 5,000 light-years from Earth. Hubble’s sharp view is able to resolve patterns and ripples in the nebula very close to the central star that is not visible from the ground.
 

 
Eye of Wolf
The Retina Nebula of the Southern sky’s Lupus constellation peers at Hubble’s Wide Field Planetary Camera. All that remains of this dying star are dense columns of dust, and a striking iris of green (hydrogen), blue (oxygen), and red (nitrogen).

 
 
Crowning Moment
As if to don a crown of heavenly jewels, the Cone Nebula rises 7 light-years into the Monoceros constellation. The column is destined to evolve into countless stars, and perhaps even generate some planets.
 
more at
http://www.space.com/php/multimedia/imagegallery/igviewer.php?imgid=5406&gid=397
 
 
Yeremiah Hardt
Yeremiah@aol.com