The M dwarf planet search programme at the ESO VLT + UVES. A search for terrestrial planets in the habitable zone of M dwarfs

We present radial velocity (RV) measurements of our sample of 40 M dwarfs from our planet search programme with VLT+UVES begun in 2000. Although with our RV precision down to 2 - 2.5 m/s and timebase line of up to 7 years, we are capable of finding planets of a few Earth masses in the close-in habitable zones of M dwarfs, there is no detection of a planetary companion. To demonstrate this we present mass detection limits allowing us to exclude Jupiter-mass planets up to 1 AU for most of our sample stars. We identified 6 M dwarfs that host a brown dwarf or low-mass stellar companion. With the exception of these, all other sample stars show low RV variability with an rms < 20 m/s. Some high proper motion stars exhibit a linear RV trend consistent with their secular acceleration. Furthermore, we examine our data sets for a possible correlation between RVs and stellar activity as seen in variations of the Halpha line strength. For Barnard's star we found a significant anticorrelation, but most of the sample stars do not show such a correlation.Comment: 13 pages, 12 figures, 5 tables, accepted by A&

A probable close brown dwarf companion to GJ 1046 (M2.5V)

Context. Brown dwarf companions to stars at separations of a few AU or less are rare objects, and none have been found so far around early-type M dwarfs M0V-M5V). With GJ 1046 (M2.5V), a strong candidate for such a system with a separation of 0.42 AU is presented. Aims. We aim at constraining the mass of the companion in order to decide whether it is a brown dwarf or a low-mass star. Methods. We employed precision RV measurements to determine the orbital parameters and the minimum companion mass. We then derived an upper limit to the companion mass from the lack of disturbances of the RV measurements by a secondary spectrum. An even tighter upper limit is subsequently established by combining the RV-derived orbital parameters with the recent new version of the Hipparcos Intermediate Astrometric Data. Results. For the mass of the companion, we derive m>26.9 MJup from the RV data. Based on the RV data alone, the probability that the companion exceeds the stellar mass threshold is just 6.2%. The absence of effects from the secondary spectrum lets us constrain the companion mass to m <229 MJup. The combination of RV and Hipparcos data yields a 3sigma upper mass limit to the companion mass of 112 MJup with a formal optimum value at m=47.2 MJup. From the combination of RV and astrometric data, the chance probability that the companion is a star is 2.9%. Conclusions. We have found a low-mass, close companion to an early-type M dwarf. While the most likely interpretation of this object is that it is a brown dwarf, a low-mass stellar companion is not fully excluded.Comment: Accepted by A&A, 6 pages, 3 figures with 4 jpg files (Fig. 3 has two panels), original version replaced as sidecaption in Figure 1 did not work. Changes in 2nd replacement: (1) Conclusions: 99.9% --> 99.73% . (2) one sentence below: the the --> the . (3) References: Joergens, V., M\"uller, A.. 2007. ApJL, in press --> ... A., 2007, ApJ 666, L11

Ultra Short Period Planets in K2: SuPerPiG Results for Campaigns 0-5

We have analyzed data from Campaigns 0-5 of the K2 mission and report 19 ultra-short-period candidate planets with orbital periods of less than 1 day (nine of which have not been previously reported). Planet candidates range in size from 0.7-16 Earth radii and in orbital period from 4.2 to 23.5 hours. One candidate (EPIC 203533312, Kp=12.5) is among the shortest-period planet candidates discovered to date (P=4.2 hours), and, if confirmed as a planet, must have a density of at least rho=8.9 g/cm^3 in order to not be tidally disrupted. Five candidates have nominal radius values in the sub-Jovian desert (R_P=3-11 R_E and P<=1.5 days) where theoretical models do not favor their long-term stability; the only confirmed planet in this range is in fact thought to be disintegrating (EPIC 201637175). In addition to the planet candidates, we report on four objects which may not be planetary, including one with intermittent transits (EPIC 211152484) and three initially promising candidates that are likely false positives based on characteristics of their light curves and on radial velocity follow-up. A list of 91 suspected eclipsing binaries identified at various stages in our vetting process is also provided. Based on an assessment of our survey's completeness, we estimate an occurrence rate for ultra-short period planets among K2 target stars that is about half that estimated from the Kepler sample, raising questions as to whether K2 systems are intrinsically different from Kepler systems, possibly as a result of their different galactic location.Comment: 13 pages, 8 figures, accepted to AJ on 2016 May 2

A Dedicated M-Dwarf Planet Search Using The Hobby-Eberly Telescope

We present first results of our planet search program using the 9.2 meter Hobby-Eberly Telescope (HET) at McDonald Observatory to detect planets around M-type dwarf stars via high-precision radial velocity (RV) measurements. Although more than 100 extrasolar planets have been found around solar-type stars of spectral type F to K, there is only a single M-dwarf (GJ 876, Delfosse et al. 1998; Marcy et al. 1998; Marcy et al. 2001) known to harbor a planetary system. With the current incompleteness of Doppler surveys with respect to M-dwarfs, it is not yet possible to decide whether this is due to a fundamental difference in the formation history and overall frequency of planetary systems in the low-mass regime of the Hertzsprung-Russell diagram, or simply an observational bias. Our HET M-dwarf survey plans to survey 100 M-dwarfs in the next 3 to 4 years with the primary goal to answer this question. Here we present the results from the first year of the survey which show that our routine RV-precision for M-dwarfs is 6 m/s. We found that GJ 864 and GJ 913 are binary systems with yet undetermined periods, while 5 out of 39 M-dwarfs reveal a high RV-scatter and represent candidates for having short-periodic planetary companions. For one of them, GJ 436 (rms = 20.6 m/s), we have already obtained follow-up observations but no periodic signal is present in the RV-data.Comment: 12 pages, 14 figures, accepted for publication in the Astronomical Journa

An m sin i = 24 Earth Mass Planetary Companion To The Nearby M Dwarf GJ 176

We report the detection of a planetary companion with a minimum mass of m sin i = 0.0771 M_Jup = 24.5 M_Earth to the nearby (d = 9.4 pc) M2.5V star GJ 176. The star was observed as part of our M dwarf planet search at the Hobby-Eberly Telescope (HET). The detection is based on 5 years of high-precision differential radial velocity (RV) measurements using the High-Resolution-Spectrograph (HRS). The orbital period of the planet is 10.24 d. GJ 176 thus joins the small (but increasing) sample of M dwarfs hosting short-periodic planets with minimum masses in the Neptune-mass range. Low mass planets could be relatively common around M dwarfs and the current detections might represent the tip of a rocky planet population.Comment: 13 pages preprint, 3 figures, submitted to Ap

Addressing "Wicked Problems" through Governance for Sustainable Development - A Comparative Analysis of National Mineral Policy Approaches in the European Union

The achievement of sustainable development (SD) in the supply of minerals poses significant challenges for governments and public administrations on all levels, because ensuring a sustainable supply constitutes a "wicked" problem that has no clear set of alternative solutions due to its social, institutional and scientific complexities. This paper explores how this problem is addressed through "governance for SD" principles (horizontal policy integration and participation; long-term vision/short-term action; and reflexivity and learning) in the design and delivery of national mineral policy strategies (NMS) in five EU Member States (Austria, Finland, Greece, Portugal and Sweden). Following a grounded theory approach on data collected through document analysis and complementary qualitative interviews, the author identified several analytical categories for the selected governance for SD' principles. Although no "one-size-fits-all" recipe for best practice on governance for SD exists in the five NMS, Finland, Portugal and Sweden meet high standards: These NMS display practical examples of governance for SD integration and, thus, lay the foundations for achieving policy outcomes in the sectoral policy strategies of the mineral supply