Koppernigk

We're still here, and maybe later out there

"Podcast host Steve Mirsky talks with human evolution expert Kate Wong about the small group of humans who survived tough times beginning about 195,000 years ago and gave rise to all of us, a story told in the cover article of the August issue of Scientific American, our 165th anniversary edition. And Editor in Chief Mariette DiChristina talks about the rest of the contents of the issue, including our coverage of the search for rocky exoplanets. Plus, we test your knowledge about some recent science in the news. Web sites related to content of this podcast include http://snipurl.com/10louu" (SciAm)

Sun not very depressive

"In a result just published astronomers have used several telescopes, including ESO’s 3.6-metre telescope at La Silla, to measure the properties of 117 Sun-like stars, of which 14 are known to host exoplanets. They measured the amount of the chemical element lithium in the stars, along with other stellar parameters. The researchers have found that the level of lithium in the stars studied decreases with the age of the star, and furthermore that the lithium levels do not behave differently in stars with known planets.

Relatively low levels of lithium are found in our Sun, compared to other Sun-like stars, and there has been much debate about the reason for the difference. One possible explanation is that the presence of planets, as found in our Solar System, may be linked with reduced levels of lithium in the host star. Such a link was indicated in research also done with ESO’s 3.6-metre telescope and its HARPS spectrograph, which was published in 2009 (see eso0942).

The new result indicates a contradiction with the earlier paper, and argues that the Sun’s lithium content is as expected when one takes its age into consideration. This is a good example of the process of scientific research: new results may build on, and in some cases contradict, earlier studies. Scientific research, which takes place at the edge of our knowledge about the Universe, is, by its very nature, a difficult, incremental process.

The research is ongoing with several teams trying to decode the lithium mystery in Sun-like stars. For example, it is thought that the rotation of a star may also affect the level of lithium observed, and that the presence of planets may affect a star’s rotation. Therefore, our understanding of possible links between lithium levels and the age of a star or the presence of planets will develop as more observations are obtained. One thing is certain: we can expect further debate in this exciting field. ... " (ESO)

Heavy, far away, yet spotted all the same

Phil Plait has an excellent report on the direct observation of an exoplanet with an Earth-bound telescope, pictured below. Here you can read it. There's even more to be found on this direct link.

Who could have imagined that it would go so fast with the discovery of exoplanets? 464 planet in the Extrasolar Planets Encyclopaedia as of June 29. That's no small potatoes. Or whatever it's not.

ESO Press kit exoplanets

ESO has released a press kit about exoplanets:

"A press kit about exoplanets is now available for download in PDF format.

Exoplanets (or extrasolar planets) are planets that orbit stars other than our Sun. While astronomers have long suspected their existence, it is only in the past two decades that we have been able to detect them, with much of this cutting edge work done at ESO.

This document explains in clear language:

* Why exoplanets are so hard to detect, and what strategies astronomers have used to find them;

* What these discoveries can tell us about the origins of our own Solar System and how the Earth was formed;

* How ESO’s Very Large Telescope (VLT) has allowed scientists to obtain the first image of an exoplanet;

* How the HARPS spectrograph on the ESO 3.6-metre telescope is the world’s foremost exoplanet hunter; and

* How future research could one day let us discover whether there is life on other planets.

The kit also contains a timeline of recent achievements in exoplanet research at ESO and details of the instruments currently used on ESO telescopes for this work.

Link"

A remarkable pic of Beta Pic

"For the first time, astronomers have been able to directly follow the motion of an exoplanet as it moves from one side of its host star to the other. The planet has the smallest orbit so far of all directly imaged exoplanets, lying almost as close to its parent star as Saturn is to the Sun. Scientists believe that it may have formed in a similar way to the giant planets in the Solar System. Because the star is so young, this discovery proves that gas giant planets can form within discs in only a few million years, a short time in cosmic terms.

Only 12 million years old, or less than three-thousandths of the age of the Sun, Beta Pictoris is 75% more massive than our parent star. It is located about 60 light-years away towards the constellation of Pictor (the Painter) and is one of the best-known examples of a star surrounded by a dusty debris disc [1]. Earlier observations showed a warp of the disc, a secondary inclined disc and comets falling onto the star. “Those were indirect, but tell-tale signs that strongly suggested the presence of a massive planet, and our new observations now definitively prove this,” says team leader Anne-Marie Lagrange. “Because the star is so young, our results prove that giant planets can form in discs in time-spans as short as a few million years.”

Recent observations have shown that discs around young stars disperse within a few million years, and that giant planet formation must occur faster than previously thought. Beta Pictoris is now clear proof that this is indeed possible. ..." (ESO)

Exoplanet's party poopers

"Astronomers hunting for planets orbiting nearby stars similar to the sun are looking for signs of rocky, Earth-like planets in a "habitable" zone, where conditions such as temperature and liquid water remain stable enough to support life.

New findings from computer modeling indicate that some of those exoplanets might fluctuate between being habitable and being inhospitable to life because of the forces exerted by giant neighbors with eccentric orbits. ..." (ScienceDaily)

Today a one meter scope, tomorrow binoculars

"Astronomers have snapped a picture of three planets orbiting a star beyond our own using a modest-sized telescope on the ground. A team at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, accomplished the surprising feat by a using a small portion of the Palomar Observatory's Hale Telescope, north of San Diego.

The planets had been imaged previously by two of the world's biggest ground-based telescopes — one of the two 10-meter telescopes of W.M. Keck Observatory and the 8-meter Gemini North Observatory, both on Mauna Kea in Hawaii. The planets, which orbit the star HR 8799, were among the very first to be directly imaged, a discovery announced in November 2008.

The new image of the planets, taken in infrared light as before, was captured using just a 4.9-foot-diameter (1.5m) portion of the Hale telescope's mirror. The astronomy team took painstaking efforts to push current technology to the point where such a small mirror could be used. They combined two techniques — adaptive optics and a coronagraph — to minimize the glare from the star and reveal the dim glow of the much fainter planets. ..." (Astronomy)

Prolate, inflated and disrupting

The orbit is so close, that the star is disrupting the planet and tearing it apart, eating up mass from its sibling. The article is published in the February 25 issue of Nature.

SPACE.com has an article about it as well. Read about the gruesome pratice of cannibalism between the stars. Often ignored, but a serious problem....

How long before we find life elsewhere? Place your bets

Years ago we wondered if our Sun was the only star with planets around it. Today we know hundreds of planets around other stars. How long will it be before we find life on one or more of them? I'd say 10 years. Bet is on.

Planet Quest - list of exoplanets

A brown dwarf next door?

"We are on the verge of uncovering a “really cool” universe of potentially millions of never before seen objects.

By “really cool” I’m not trying to sound hippy-dippy, but rather am talking about objects in space that are less than 1,000 degrees Fahrenheit.

And, this might lead us down the path to an interstellar mission to a cryoplanet where surface temperatures hover tens of degrees above absolute zero.

This “cool” survey of the comparatively chilly universe will be conducted by NASA’s WISE mission (Wide Infrared Survey Explorer). The mission’s small cryogenic space telescope in a Thermos bottle is scheduled to launch on Dec. 9 from Vandenberg Air Force Base in California. It will complete making an all-sky infrared map by the middle of next year. The catalog is expected to reveal the coolest stars, 100,000 asteroids, and some of the brightest star forming galaxies that are shrouded in dust, among many other targets.

I’m predicting two potentially news breaking headlines from WISE (and no doubt there will be other stories too). The first would be the discovery of an entirely new class of dark astronomical object that has previously escaped detection. Since I can’t imagine what that could be, there isn’t much more I can say except to expect the unexpected.

The other headline would be the discovery of a brown dwarf that is even closer to Earth than the nearest star, the Alpha Centauri system at 4.3 light-years. Brown dwarfs are objects that form along with stars but do not have enough mass to trigger or sustain nuclear fusion. They are so cool and dim very little is known about their distribution in the galaxy...." (Discovery)

Noisy Kepler

Hmm, sometimes science looks like crawling before walking. Well, hey, maybe it is that way. Nevertheless a disappointment that could end well. Remember Hubble, right?

"Kepler, NASA's mission to search for planets around other stars, will not be able to spot an Earth-sized planet until 2011, according to the mission's team. The delays are caused by noisy amplifiers in the telescope's electronics. The team is racing to fix the issue by changing the way data from the telescope is processed, but the delay could mean that ground-based observers now have the upper hand in the race to be the first to spot an Earth twin." (Nature)

...30, 31, 32 - anybody?

"Today, at an international ESO/CAUP exoplanet conference in Porto, the team who built the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph for ESO's 3.6-metre telescope, reports on the incredible discovery of some 32 new exoplanets, cementing HARPS's position as the world’s foremost exoplanet hunter. This result also increases the number of known low-mass planets by an impressive 30%. Over the past five years HARPS has spotted more than 75 of the roughly 400 or so exoplanets now known..." (ESO)

Dirty Starry

"Some stars are lonely behemoths, with no surrounding planets or asteroids, while others sport a skirt of attendant planetary bodies. New research published this week in The Astrophysical Journal Letters explains why the composition of the stars often indicates whether their light shines into deep space, or whether a small fraction shines onto orbiting planets...." (ScienceDaily)

Water, water everywhere

"When NASA announced last month the finding of water ice in several impact craters on Mars, and either water or hydroxyl widely dispersed on the moon's surface, the solar system became a little more familiar because it seemed a tad more hospitable to life as we know it on Earth.

But is that because the rest of the cosmos has much in common with Earth or vice versa? Water, the unique molecule that cradles and nurtures life here, is apparently common and perhaps abundant in the solar system. Observational evidence suggests that water as a solid, liquid or gas is present at the poles of Mercury, within the thick clouds of Venus, on Mars, inside asteroids and comets, and on Jupiter, Saturn, Uranus and Neptune. Scientists also have speculated that Jupiter's moons Europa, Ganymede and Callisto have vast subsurface oceans of liquid water. They have also detected through spectroscopy water frost on Pluto's moon, Charon. Of course, scientists have known that H2O also seems to be ubiquitous beyond the solar system. They've detected it in one form or another in interstellar gas and even in such unlikely places as the atmospheres of stars. Perhaps it shouldn't be such a revelation. After all, hydrogen is the most common element in the universe, followed by helium and oxygen..." (SciAm)

Solid evidence for a small solid planet

"The longest set of HARPS measurements ever made has firmly established the nature of the smallest and fastest-orbiting exoplanet known, CoRoT-7b, revealing its mass as five times that of Earth's. Combined with CoRoT-7b's known radius, which is less than twice that of our terrestrial home, this tells us that the exoplanet's density is quite similar to the Earth's, suggesting a solid, rocky world. The extensive dataset also reveals the presence of another so-called super-Earth in this alien solar system...." (ESO)

Wrong way

"Planets orbit stars in the same direction that the stars rotate. They all do. Except one.

A newfound planet orbits the wrong way, backward compared to the rotation of its host star. Its discoverers think a near-collision may have created the retrograde orbit, as it is called.

The star and its planet, WASP-17, are about 1,000 light-years away. The setup was found by the UK's Wide Area Search for Planets (WASP) project in collaboration with Geneva Observatory. The discovery was announced today but has not yet been published in a journal.

"I would have to say this is one of the strangest planets we know about," said Sara Seager, an astrophysicist at MIT who was not involved in the discovery..." (SPACE.com)

Waiting to spot Another Earth

"The first results are in from the Kepler orbiting observatory, the world's most powerful planet-searching telescope, and according to MIT planetary scientist Sara Seager they show that the instrument should have no trouble detecting "alien Earths" -- planets that are about the size of our own...."(MIT)

Some future scenarios

"The discovery of a giant planet orbiting the tiny star VB10 made headlines earlier this year as the smallest star ever to be found harboring a planet. But Greg Laughlin, an astronomer at the University of California, Santa Cruz, suggests that the VB10 system could also be a glimpse into the very distant future of our own galaxy. ..." (Planet Quest)

A tilted race course

"An international team of researchers has found a planet around another star whose orbit is steeply tilted from the plane of the star's equator, a finding that contradicts some theories about how solar systems form.

In our own solar system, all of the planets orbit the sun almost exactly in the same plane as the sun's rotation - and that alignment is required by currently accepted theories of how stars and planets form from a collapsing disk of dust and gas. Any misalignment, such as the one the team found, must have occurred as a result of a disturbance sometime after the planet's formation, theorists say.

Astronomers are interested in exploring the characteristics of such distant planets partly to help refine theories of planet formation, and partly just to understand the kinds of variations that may be possible in the universe around us - to "see how the dice get rolled in other solar systems," says MIT physicist Joshua Winn, who led the team that measured the planet's tilted orbit...."(MIT)

Don't stop in the Milky Way

It might be possible to find exoplanets in the halo of the Andromeda galaxy, some 2.2 million light years away. The technique used is pixel lensing.

The abstract can be found here, a more thorough explanation can be found at Centauri Dreams.