Category Archives: Exoplanets

Kepler Observatory operators will try to heal failed reaction wheels

There’s still some hope for the orbiting Kepler exoplanet searcher:

Kepler Mission Manager Update: Preparing for Recovery

Operations in Point Rest State (PRS) have continued for the spacecraft. The spacecraft was placed in PRS on May 15, 2013, after the failure of reaction wheel 4. It has been 53 days since the spacecraft collected new science data.

As noted in the last update, the team has made adjustments to onboard fault parameters for the star trackers to lessen the possibility of entry into safe mode. We have also made additional adjustments to the Thruster-Control Safe Mode to improve its fuel efficiency. This provides yet more protection for spacecraft fuel reserves while the team continues to work on reaction wheel performance assessment and recovery plans.

The engineering team has devised initial tests for the recovery attempt and is checking them on the spacecraft test bed at the Ball Aerospace facility in Boulder, Colo. The team anticipates that exploratory commanding of Kepler’s reaction wheels will commence mid-to-late July. The Kepler spacecraft will remain in PRS until and during the tests.

Later this month, an update to the data processing pipeline software will be deployed. Called SOC 9.1, this enhancement has been underway for several months and is in the final stages of verification and validation. This software release provides additional refinements to better tease out small planet signatures from the four years of Kepler data. It will also decrease the frequency of false positives.

The team continues to disposition Kepler Objects of Interest (KOIs) found by searching the observational data from Quarters 1 to Quarter 12. With 63 more planet candidates added since the last report, the count now stands at 3,277.

While Kepler data analysis continues, we were pleased to note the discoveries recently announced by European Southern Observatory (ESO).  A team of astronomers has combined new observations of Gliese 667C with existing data from HARPS at ESO’s 3.6-metre telescope in Chile, revealing a system with at least six planets. A record-breaking three of these planets are super-Earths lying in the zone around the star where liquid water might exist, making them possible candidates for the presence of life. This is the first system found with a fully packed habitable zone.

Also this month, a research team from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., used Kepler data to find two planets smaller than three times the size of Earth orbiting sun-like stars in a one billion year old star cluster named NGC 6811. The result demonstrates that small planets can form and persist in an open cluster, and casts the net wider in the search for planets the size and temperature of Earth. With this discovery, 134 planets have been confirmed using Kepler data.

And, finally we note the announcement from France’s space agency, Centre National d’Etudes Spatiales (CNES), on the retirement of the Convection, Rotation, and planetary Transits (CoRoT) mission. The CoRoT spacecraft was launched Dec. 26, 2006, and paved the way for Kepler in terms of space-based identification of transiting exoplanets and also the detection of acoustic oscillations in sun-like stars. We congratulate CNES on a great run with the CoRoT spacecraft!

Regards,
Roger

Three planets detected in habitable zone of nearby star – ESO

The European Southern Observatory (ESO) has released the results of  a study of the star Gliese 667C showing that at least 6 planets orbit around it and that three of these are rocky planets (called “super-Earths because they are more massive than earth) within its habitable zone. (The planets are not seen directly but are detected via the Doppler variations in the light of the star as the planets pull it back and forth relative to us as they orbit around it.) This is the first time so many such planets have been seen within a habitable zone. Paul Gilster offers some analysis of the results:  Gliese 667C: Three Habitable Zone Planets – Centauri Dreams.

Three Planets in Habitable Zone of Nearby Star

A team of astronomers has combined new observations of Gliese 667C with existing data from HARPS [High Accuracy Radial velocity Planet Searcher] at ESO’s 3.6-metre telescope in Chile, to reveal a system with at least six planets. A record-breaking three of these planets are super-Earths lying in the zone around the star where liquid water could exist, making them possible candidates for the presence of life. This is the first system found with a fully packed habitable zone.

Gliese 667C is a very well-studied star. Just over one third of the mass of the Sun, it is part of a triple star system known as Gliese 667 (also referred to as GJ 667), 22 light-years away in the constellation of Scorpius (The Scorpion). This is quite close to us — within the Sun’s neighbourhood — and much closer than the star systems investigated using telescopes such as the planet-hunting Kepler space telescope.

This video sequence shows an artist’s impression of the view from the exoplanet
Gliese 667Cd looking towards the planet’s parent star (Gliese 667C). In the
background to the right the more distant stars in this triple system (Gliese 667A
and Gliese 667B) are visible and to the left in the sky one of the other planets, the
newly discovered Gliese 667Ce, can be seen as a crescent.

Previous studies of Gliese 667C had found that the star hosts three planets (eso0939, eso1214) with one of them in the habitable zone. Now, a team of astronomers led by Guillem Anglada-Escudé of the University of Göttingen, Germany and Mikko Tuomi of the University of Hertfordshire, UK, has reexamined the system. They have added new HARPS observations, along with data from ESO’s Very Large Telescope, the W.M. Keck Observatory and the Magellan Telescopes, to the already existing picture [1]. The team has found evidence for up to seven planets around the star [2].

These planets orbit the third fainter star of a triple star system. Viewed from one of these newly found planets the two other suns would look like a pair of very bright stars visible in the daytime and at night they would provide as much illumination as the full Moon. The new planets completely fill up the habitable zone of Gliese 667C, as there are no more stable orbits in which a planet could exist at the right distance to it.

We knew that the star had three planets from previous studies, so we wanted to see whether there were any more,” says Tuomi. “By adding some new observations and revisiting existing data we were able to confirm these three and confidently reveal several more. Finding three low-mass planets in the star’s habitable zone is very exciting!

Three of these planets are confirmed to be super-Earths — planets more massive than Earth, but less massive than planets like Uranus or Neptune — that are within their star’s habitable zone, a thin shell around a star in which water may be present in liquid form if conditions are right. This is the first time that three such planets have been spotted orbiting in this zone in the same system [3].

The number of potentially habitable planets in our galaxy is much greater if we can expect to find several of them around each low-mass star — instead of looking at ten stars to look for a single potentially habitable planet, we now know we can look at just one star and find several of them,” adds co-author Rory Barnes (University of Washington, USA).

Compact systems around Sun-like stars have been found to be abundant in the Milky Way. Around such stars, planets orbiting close to the parent star are very hot and are unlikely to be habitable. But this is not true for cooler and dimmer stars such as Gliese 667C. In this case the habitable zone lies entirely within an orbit the size of Mercury’s, much closer in than for our Sun. The Gliese 667C system is the first example of a system where such a low-mass star is seen to host several potentially rocky planets in the habitable zone.

This video shows the orbital motions of the planets around the star Gliese 667C.
Three of these planets are super-Earths orbiting in the habitable zone where liquid
water may exist. The orbit of the planet Mercury in the Solar System is included for
scale. As Gliese 667C is fainter and cooler than the Sun the habitable zone is much
closer to the star than in the Solar System.

The ESO scientist responsible for HARPS, Gaspare Lo Curto, remarks: “This exciting result was largely made possible by the power of HARPS and its associated software and it also underlines the value of the ESO archive. It is very good to also see several independent research groups exploiting this unique instrument and achieving the ultimate precision.

And Anglada-Escudé concludes: “These new results highlight how valuable it can be to re-analyse data in this way and combine results from different teams on different telescopes.

Continue for more details…

A better equation to estimate number of life friendly planets

The title is a bit misleading (no it’s not “exact”) but here is an interesting discussion of new formula from Prof. Sara Seager (MIT) that provides an estimate of “the number of planets with detectable biosignature gases” using data from exoplanet searches like that done with the Kepler space observatory along with a few guessed parameters:   A New Equation Reveals Our Exact Odds of Finding Alien Life – io9.com.

WFIRST to use donated space telescope for exoplanet imaging

The WFIRST (Wide Field Infra-Red Survey Telescope) project aims to use one of the space telescopes donated to NASA by the National Reconnaissance Office (NRO) last year primarily for the study of distant supernova and galaxies. However, it also will “be a bonanza for exoplanet studies” : Exoplanet capabilities of WFIRST-2.4 – The Space Review

In addition to microlensing to detect exoplanets, a coronagraph

will block out a large fraction of the light of target stars. With much of the glare of parent stars suppressed, the telescope will be able to directly image any planets orbiting that star. The goal is to produce as narrow an image of the space around the star as possible. This is referred to as the Inner Working Angle (IWA). The more that the IWA can be shrunk, the more inner planets can be imaged. It is possible that the enhanced WFIRST may be able to view planets as close as 1 astronomical unit (AU) to their parent star, depending on their distance from our solar system.

John Kelly applauds the use of surplus assets : Sharing technology leaps us ahead – Florida Today