In this SETI Institute talk, Elisa Quintana talks about Earth-Sized Planets in the Habitable Zones of Cool Stars:

Caption:

Abstract: A primary goal of the Kepler mission is to determine the frequency of Earth-sized planets in the habitable zones of other stars. M dwarfs, stars that are smaller and cooler than the Sun, comprise more than 70% of the stars in our galaxy. Finding that Earth-sized planets around M dwarfs are common, therefore, has big implications for determining the frequency of other Earths.

In April 2014 we announced the discovery of Kepler-186f, the first definitive Earth-sized planet found to orbit in the habitable zone of a star other than our Sun. We will discuss our methods of combining ground-based observations with transit modeling to confirm this system, and will present our theoretical studies on the formation and habitability of this planet. We will also present updates on several promising multi-planet systems that have Earth-sized, and possibly sub-Earth-sized, candidates in the habitable zones of cool low-mass stars in the Kepler field-of-view.

The Spitzer infrared space telescope spotted the debris cloud from what looks to be the collision of two asteroids around a star 1200 light years away from us.

NASA’s Spitzer Telescope Witnesses Asteroid Smashup

NASA’s Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the formation of planets.

Scientists had been regularly tracking the star, called NGC 2547-ID8, when it surged with a huge amount of fresh dust between August 2012 and January 2013.

This artist’s concept shows the immediate aftermath of a large asteroid impact around
NGC 2547-ID8, a 35-million-year-old sun-like star thought to be forming rocky planets.
Image credit: NASA/JPL-Caltech

“We think two big asteroids crashed into each other, creating a huge cloud of grains the size of very fine sand, which are now smashing themselves into smithereens and slowly leaking away from the star,” said lead author and graduate student Huan Meng of the University of Arizona, Tucson.

While dusty aftermaths of suspected asteroid collisions have been observed by Spitzer before, this is the first time scientists have collected data before and after a planetary system smashup. The viewing offers a glimpse into the violent process of making rocky planets like ours.

Rocky planets begin life as dusty material circling around young stars. The material clumps together to form asteroids that ram into each other. Although the asteroids often are destroyed, some grow over time and transform into proto-planets. After about 100 million years, the objects mature into full-grown, terrestrial planets. Our moon is thought to have formed from a giant impact between proto-Earth and a Mars-size object.

In the new study, Spitzer set its heat-seeking infrared eyes on the dusty star NGC 2547-ID8, which is about 35 million years old and lies 1,200 light-years away in the Vela constellation. Previous observations had already recorded variations in the amount of dust around the star, hinting at possible ongoing asteroid collisions. In hope of witnessing an even larger impact, which is a key step in the birth of a terrestrial planet, the astronomers turned to Spitzer to observe the star regularly. Beginning in May 2012, the telescope began watching the star, sometimes daily.

A dramatic change in the star came during a time when Spitzer had to point away from NGC 2547-ID8 because our sun was in the way. When Spitzer started observing the star again five months later, the team was shocked by the data they received.

“We not only witnessed what appears to be the wreckage of a huge smashup, but have been able to track how it is changing — the signal is fading as the cloud destroys itself by grinding its grains down so they escape from the star,” said Kate Su of the University of Arizona and co-author on the study. “Spitzer is the best telescope for monitoring stars regularly and precisely for small changes in infrared light over months and even years.”

Space Images: Witnessing a Planetary Wreckage

A very thick cloud of dusty debris now orbits the star in the zone where rocky planets form. As the scientists observe the star system, the infrared signal from this cloud varies based on what is visible from Earth. For example, when the elongated cloud is facing us, more of its surface area is exposed and the signal is greater. When the head or the tail of the cloud is in view, less infrared light is observed. By studying the infrared oscillations, the team is gathering first-of-its-kind data on the detailed process and outcome of collisions that create rocky planets like Earth.

“We are watching rocky planet formation happen right in front of us,” said George Rieke, a University of Arizona co-author of the new study. “This is a unique chance to study this process in near real-time.”

The team is continuing to keep an eye on the star with Spitzer. They will see how long the elevated dust levels persist, which will help them calculate how often such events happen around this and other stars. And they might see another smashup while Spitzer looks on.

The results of this study are posted online Thursday in the journal Science.

NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

For more information about Spitzer, visit: http://www.nasa.gov/spitzer

The Hubble telescope looks at three gas giants, or “Hot Jupiters”, around distant stars that are similar to our sun and find little sign of water: Surprised scientists come up ‘nearly dry’ in search for water on ‘hot Jupiter’ planets – The Washington Post

Here is the NASA press release:

Hubble Finds Three Surprisingly Dry Exoplanets

Astronomers using NASA’s Hubble Space Telescope have gone looking for water vapor in the atmospheres of three planets orbiting stars similar to the sun — and have come up nearly dry.

The three planets, known as HD 189733b, HD 209458b, and WASP-12b, are between 60 and 900 light-years away from Earth and were thought to be ideal candidates for detecting water vapor in their atmospheres because of their high temperatures where water turns into a measurable vapor.

These so-called “hot Jupiters” are so close to their star they have temperatures between 1,500 and 4,000 degrees Fahrenheit, however, the planets were found to have only one-tenth to one one-thousandth the amount of water predicted by standard planet-formation theories.

“Our water measurement in one of the planets, HD 209458b, is the highest-precision measurement of any chemical compound in a planet outside our solar system, and we can now say with much greater certainty than ever before that we’ve found water in an exoplanet,” said Nikku Madhusudhan of the Institute of Astronomy at the University of Cambridge, England. “However, the low water abundance we have found so far is quite astonishing.”

Madhusudhan, who led the research, said that this finding presents a major challenge to exoplanet theory. “It basically opens a whole can of worms in planet formation. We expected all these planets to have lots of water in them. We have to revisit planet formation and migration models of giant planets, especially “hot Jupiters,” and investigate how they’re formed.”

He emphasizes that these results may have major implications in the search for water in potentially habitable Earth-sized exoplanets. Instruments on future space telescopes may need to be designed with a higher sensitivity if target planets are drier than predicted. “We should be prepared for much lower water abundances than predicted when looking at super-Earths (rocky planets that are several times the mass of Earth),” Madhusudhan said.

Using near-infrared spectra of the planets observed with Hubble, Madhusudhan and his collaborators estimated the amount of water vapor in each of the planetary atmospheres that explains the data.

The planets were selected because they orbit relatively bright stars that provide enough radiation for an infrared-light spectrum to be taken. Absorption features from the water vapor in the planet’s atmosphere are detected because they are superimposed on the small amount of starlight that glances through the planet’s atmosphere.

Detecting water is almost impossible for transiting planets from the ground because Earth’s atmosphere has a lot of water in it, which contaminates the observation. “We really need the Hubble Space Telescope to make such observations,” said Nicolas Crouzet of the Dunlap Institute at the University of Toronto and co-author of the study.

The currently accepted theory on how giant planets in our solar system formed, known as core accretion, states a planet is formed around the young star in a protoplanetary disk made primarily of hydrogen, helium, and particles of ices and dust composed of other chemical elements. The dust particles stick to each other, eventually forming larger and larger grains. The gravitational forces of the disk draw in these grains and larger particles until a solid core forms. This then leads to runaway accretion of both solids and gas to eventually form a giant planet.

This theory predicts that the proportions of the different elements in the planet are enhanced relative to those in its star, especially oxygen, which is supposed to be the most enhanced. Once the giant planet forms, its atmospheric oxygen is expected to be largely encompassed within water molecules. The very low levels of water vapor found by this research raise a number of questions about the chemical ingredients that lead to planet formation.

“There are so many things we still don’t know about exoplanets, so this opens up a new chapter in understanding how planets and solar systems form,” said Drake Deming of the University of Maryland, who led one of the precursor studies. “The problem is that we are assuming the water to be as abundant as in our own solar system. What our study has shown is that water features could be a lot weaker than our expectations.”

The findings are published July 24 in The Astrophysical Journal Letters.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For images and more information about Hubble, visit: www.nasa.gov/hubble

and hubblesite.org/news/2014/36