It is sunrise here in the Alps and a very good night has just gone by. While analyzing the data collected last night, we observed an M dwarf of the Apache Input Catalogue flaring (see the light curve in figure. Time (HJD) is on the X-axis). Instead, tonight the star was quite all the time. Since July 2012, when APACHE officially started, it is the first time that we clearly observe a stellar flare occurring on one of our target stars. This should mean that our observing strategy is sensible to flares, which usually last just for few minutes. The star seems to be a mid M dwarf and it should be located at nearly 75 light years from us: when the flare occurred, the Earth was plagued by the Second World War. We did not find in literature any information concerning the activity of this red dwarf, so this appears to be a new finding from APACHE!
This is for sure a very hot topic! The lively debate concerning the occurrence rate of habitable terrestrial planets around red dwarfs produced a new paper by R. Kopparapu (Penn State University) accepted by the Astrophysical Journal Letters and available here as a pre-print. The manuscript entitled A revised estimate of the occurrence rate of terrestrial planets in the habitable zones around Kepler M-dwarfs is an update of the recent paper by Dressing & Charbonneau that we have advertised in a previous post. According to the new calculations of Kopparapu, based on the Kepler data and new estimated limits for the Habitable Zone (HZ) boundaries, the frequency of terrestrial planets (0.5-1.4 Earth radius) in the HZ of cool stars is increased to 0.48-0.53, while Dressing & Charbonneau calculated the lower value 0.15. Assuming Earth-size planets with 0.5 – 2 Earth radius, the frequency increases to 0.51-0.61 planet/star. So, the potential for finding Earth-like planets around M dwarfs may be higher than previously reported, and the Apaches will search for them with greater enthusiasm!
Today we have received and mounted the telescope number 5 of the APACHE array. In few days it will be operating with the other four already functioning since July, 2012.
Superman locates his home planet Krypton around an M-dwarf… but that star is not a target observed by APACHE!0
Recently, Superman has found the location of his home planet Krypton (http://www.guardian.co.uk/culture/us-news-blog/2012/nov/05/neil-degrasse-tyson-superman-planet). It is orbiting the close M-dwarf star LHS 2520, that is located 27.1 light years from Earth. Unfortunately, the APACHE observations can not confirm the existence of the planet because the star is not included in the list of the monitored targets… However, APACHE is looking for planets which could be home of other super heroes! Stay tuned.
The APACHE Project will be presented tomorrow (7th November, 2012 at session 2/3: 12.00-12.20) at the GREAT-ESF Workshop “GAIA and Exoplanets: GREAT Synergies at the Horizons in Turin Nov 5-7, 2012.
We will be there with an oral contribution of Mario Damasso, PhD Student at Doctoral School in Astronomy, University of Padova, and scientific researcher at the OAVdA:
The APACHE Project: searching for transiting planets around cool stars
Here you can find the abstract and more information.
and with a poster by Jean Marc Christille, PhD Student, University of Perugia and scientific researcher at the OAVdA:
THE APACHE Survey Hardware and Software Design: Tools for an Automatic Search of Small-size Transiting Exoplanets
Here you can find the abstract and more information
As soon as possible we will publish the slides and the poster.
The search for habitable planets around nearby M dwarfs is really a very appealing topic in the field of exoplanets. This fact is confirmed by the recently announced meeting Transiting Planets in the House of the Sun – A Workshop on M Dwarf Stars and Their Planets, to be held in the island of Maui (Hawaii, US) on June 3-6 2012.
On 5th December the scientific team of the Kepler space telescope announced the discovery, made with the photometric transit method, of the first potentially habitable planet around a star very similar to our Sun.
The scientific community (and not only) is now waiting for the paper to appear in The Astrophysical Journal but, even if this announcement represents a milestone for the search for an Earth twin, some caveats should be kept in mind when discussing the results: realistically, should Kepler-22b be still considered a candidate instead of a confirmed planet? Even if its orbital period is compatible with its parent star’s habitable zone, is Kepler-22b really well characterized as a planet, despite it has a small radius (roughly 2.4 times the radius of Earth)? (continua…)
Today a paper by J. A. Johnson and collaborators appeared in Astro-ph (http://arxiv.org/pdf/1112.0017), reporting the confirmation and characterization of the first Hot Jupiter discovered orbiting a red dwarf (in this case an early-type M dwarf). The paper has not been submitted yet. The planet has a period of ~2.5 days and a radius very close to the radius of Jupiter, and was originally discovered by the Kepler mission using the photometric transit method. Despite the faintness of the star KOI-254 (V~17 mag), also known as 2MASS 19312949+4103513), the authors were able to confirm spectroscopically the planetary nature of the companion, estimating for the mass of the planet nearly half the mass of Jupiter.
For a challenging survey as APACHE project it is very important to select the best targets. Almost 3000 M dwarfs must be monitored photometrically, and it is fundamental to find some useful criteria for picking up the most promising stars (anyway, a stroke of luck is always welcome!). For instance, stars with a particularly high level of chromospheric activity seem not to be suitable targets to search for planets, because the star activity makes the measurements of radial velocity -which are necessary to confirm a transiting planetary candidate- very complicated (stellar jitters).