Friday, 8 August 2014

Supernovas Might Create Weird 'Zombie Stars'

Supernovas Might Create Weird 'Zombie Stars'

Solar System Evolution: Peering Back at the Sun's Cosmic Womb

Solar System Evolution: Peering Back at the Sun's Cosmic Womb

Looking for ET's Industrial Pollution on Alien Worlds

Looking for ET's Industrial Pollution on Alien Worlds

If ET is anything like us, scientists may be able to ferret out advanced civilizations beyond Earth by scanning planets’ atmospheres for telltale industrial pollutants. 
Researchers looked at two ozone-eating chlorofluorocarbons (CFCs) that would be easy to detect with the infrared light-splitting spectrometer being built for the James Webb Space Telescope, a follow-on to the Hubble observatory that is due to launch in 2018.
The targets would be white dwarf stars, which are much smaller than the sun. An Earth-sized orbiting planet passing by, relative to the telescope’s line of sight, would block a significant amount of the parent star’s light, allowing for relatively quick scans.
“We consider industrial pollution a biomarker for intelligent life,” Henry Lin, a Harvard University undergraduate and Intel Foundation Young Scientist Award recipient, told Discovery News.
"However, maybe this super-sophisticated alien civilization ... would consider industrial pollution a sign of unintelligent life. After all, it doesn’t seem very intelligent to pollute your own atmosphere with things that can make life difficult," he said.
Lin’s advisor and research collaborator Avi Loeb, also at Harvard, offers a caveat: Perhaps ET purposely engineered or terraformed its atmosphere to make a cold planet like Mars habitable.
“In principle, there might be a reason for why pollution is a good thing,” Loeb told Discovery News.
Lin, Loeb and atmospheric chemist Gonzalo Gonzalez Abad, with the Harvard-Smithsonian Center for Astrophysics, studied two types of easily detectable CFCs -- tetrafluoromethane (CF4) and trichlorofluoromethane (CCl3F), both of which are produced by industrial processes.
Based on computer models, they estimate that planets circling in the so-called "habitable zone" of parent white dwarf stars would have a two-minute transit, relative to Earth's line of sight, every 10 hours. The habitable zones are temperature regions where water can exist as a liquid on a planet's surface. Water is believed to be necessary for life.
The next step would be to find transiting planets and use the eclipses to capture light filtering through the planets' atmospheres. Chemicals in the atmosphere leave telltale signatures that can be analyzed for oxygen and other molecules associated with life, as well as for industrial pollutants, the scientists say.
“The advantage of this approach is that we don’t have to build a new instrument to search for intelligent life,” Lin said.

Alien Life 'Inevitable' and We Could Detect It Within 20 Years

Alien Life 'Inevitable' and We Could Detect It Within 20 Years

As astronomical instrumentation becomes more sophisticated, we are rapidly approaching a crossroads in the search for extraterrestrial life, according to a leading planetary scientist. It’s also “inevitable” that alien life exists in the universe given the preponderance of extrasolar planets that are being discovered — it’s up to us to seek out the extraterrestrial biosignatures.
These conclusions are outlined by Sara Seager, Professor of Planetary Science and Physics at the Massachusetts Institute of Technology (MIT), in a paper published in the journal Proceedings of the National Academy of Sciences on Aug. 4.
“In the coming decade or two, we will have a lucky handful of potentially habitable exoplanets with atmospheres that can be observed in detail with the next generation of sophisticated space telescopes,” writes Seager, pointing out that NASA’s James Webb Space Telescope (JWST) and a planned direct-imaging space telescope will be able to seek out biosignatures (i.e. chemicals created by extraterrestrial biology) in the atmospheres of nearby exoplanets. The JWST is set for launch in 2018.
“Life can be inferred by the presence of atmospheric biosignature gases — gases produced by life that can accumulate to detectable levels in an exoplanet atmosphere,” she writes.
To date, a handful of exoplanetary atmospheres have been studied through the analysis of their host star’s light passing through their atmospheres. As an alien world orbits its star, from our perspective, it may block some of the starlight from view and be registered as a “transit.” The transit method is used by NASA’s Kepler space telescope and has so far confirmed the detection of hundreds of exoplanets. But this method can also help us analyze the chemicals contained in exoplanetary atmospheres.
During a transit, if that exoplanet has an atmosphere, some of the starlight is filtered through its atmosphere. Some wavelengths of that light are absorbed by specific chemicals, leaving a spectroscopic ‘fingerprint’ in the starlight we detect. Although only the largest class of exoplanets have so far had their atmospheres analyzed in this way (gas giants with tight orbits around their stars known as “hot-Jupiters”), Seager argues that with the advent of advanced space telescopes, the composition of smaller worlds’ atmospheres could also studied. Habitable “super-Earths” fall into this category.
Once this happens, we can begin to observe small rocky worlds, potentially detecting spectroscopic signatures of chemicals associated with life.
Although the next generation of space telescopes may be able to detect biosignatures in nearby exoplanets, Seager urges caution.
“(M)any different gases are produced by life, but the anticipated diversity of exoplanet atmosphere composition and host star environments may yield different detectable biosignature gases than the terrestrial examples. Even with excellent data, false positives will drive a permanent ambiguity in many cases,” she adds.
Molecules such as methane can be generated through biological (methanogenic) and geological (volcanic) processes, so the detection of methane in an exoplanetary atmosphere may not indicate life. To find out what is generating that gas, astronomers will need to study the atmosphere in its entirety to avoid jumping to conclusions about that world’s biological potential. The identification of these “false positives,” using advanced instrumentation, will be critical when seeking out genuine biosignatures.
The advances in space-based observatories are tantalizing and, with the launch of JWST and other advanced direct imaging telescopes (such as the “star shade” concept), we could start studying small habitable worlds with atmospheres and teasing hints as to any biosignatures within the next couple of decades.
But to fully investigate this exciting class of exoplanet, “we require the ability to directly image exoplanets orbiting 1,000 or more of the nearest sun-like stars.” Such an endeavor would require ahuge space-borne observatory — an optical telescope with a diameter exceeding 10 meters. Considering the Hubble Space Telescope is only 2.4 meters in diameter, the exoplanetary atmosphere telescopes of the future will require some huge innovative leaps before they become a reality.
One thing seems certain, however. The longer we gaze into the stars, the more certain we become about the possibility for life beyond Earth.
“Our own Galaxy has 100 billion stars, and our Universe has upwards of 100 billion galaxies — making the chance for life elsewhere seem inevitable based on sheer probability,” writes Seager. “We can say with certainty that, for the first time in human history, we are finally on the verge of being able to search for signs of life beyond our solar system around the nearest hundreds of stars.”

Rosetta Spacecraft makes Historic Arrival at Comet

Europe's Rosetta Spacecraft Makes Historic Arrival at Comet