HD 5583 and BD+15 2375: Two Evolved Giant Stars With Warm Jupiters

Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. III. HD 5583 and BD+15 2375 - two cool giants with warm companions

Authors:

Niedzielski et al

Abstract:

Evolved stars are crucial pieces to understand the dependency of the planet formation mechanism on the stellar mass and to explore deeper the mechanism involved in star-planet interactions. Over the past ten years, we have monitored about 1000 evolved stars for radial velocity variations in search for low-mass companions under the Penn State - Torun Centre for Astronomy Planet Search program with the Hobby-Eberly Telescope. Selected prospective candidates that required higher RV precision measurements have been followed with HARPS-N at the 3.6 m Telescopio Nazionale Galileo under the TAPAS project.

We aim to detect planetary systems around evolved stars to be able to build sound statistics on the frequency and intrinsic nature of these systems, and to deliver in-depth studies of selected planetary systems with evidence of star-planet interaction processes. For HD 5583 we obtained 14 epochs of precise RV measurements collected over 2313 days with the Hobby-Eberly Telescope (HET), and 22 epochs of ultra-precise HARPS-N data collected over 976 days. For BD+15 2375 we collected 24 epochs of HET data over 3286 days and 25 epochs of HARPS-S data over 902 days.

We report the discovery of two planetary mass objects orbiting two evolved Red Giant stars: HD~5583 has a m sin i = 5.78 MJ companion at 0.529~AU in a nearly circular orbit (e=0.076), the closest companion to a giant star detected with the RV technique, and BD+15~2735 that with a m sin i= 1.06 MJ holds the record of the lightest planet found so far orbiting an evolved star (in a circular e=0.001, 0.576~AU orbit). These are the third and fourth planets found within the TAPAS project, a HARPS-N monitoring of evolved planetary systems identified with the Hobby-Eberly Telescope.

Revising the Kepler-10 System for Exoplanet Characteristics & Adding Kepler-10d (KOI-72.X)

Revised Masses and Densities of the Planets around Kepler-10

Authors:

Weiss et al

Abstract:

Determining which small exoplanets have stony-iron compositions is necessary for quantifying the occurrence of such planets and for understanding the physics of planet formation. Kepler-10 hosts the stony-iron world Kepler-10b (K10b), and also contains what has been reported to be the largest solid silicate-ice planet, Kepler-10c (K10c). Using 220 radial velocities (RVs), including 72 precise RVs from Keck-HIRES of which 20 are new from 2014-2015, and 17 quarters of Kepler photometry, we obtain the most complete picture of the Kepler-10 system to date. We find that K10b (Rp=1.47 Re) has mass 3.72±0.42 Me and density 6.46±0.73 g/cc. Modeling the interior of K10b as an iron core overlaid with a silicate mantle, we find that the iron core constitutes 0.17±0.11 of the planet mass. For K10c (Rp=2.35 Re) we measure Mp=13.98±1.79 Me and ρ=5.94±0.76 g/cc, significantly lower than the mass computed in Dumusque et al. (2014, 17.2±1.9 Me). Internal compositional modeling reveals that at least 10% of the radius of Kepler-10c is a volatile envelope composed of hydrogen-helium (0.2% of the mass, 16% of the radius) or super-ionic water (28% of the mass, 29% of the radius). Analysis of only HIRES data yields a higher mass for K10b and a lower mass for K10c than does analysis of the HARPS-N data alone, with the mass estimates for K10c formally inconsistent by 3σ. Splitting the RVs from each instrument leads to inconsistent measurements for the mass of planet c in each data set. This suggests that time-correlated noise is present and that the uncertainties in the planet masses (especially K10c) exceed our formal estimates. Transit timing variations (TTVs) of K10c indicate the likely presence of a third planet in the system, KOI-72.X. The TTVs and RVs are consistent with KOI-72.X having an orbital period of 24, 71, or 101 days, and a mass from 1-7 Me.

HD 175607b: a Hot Neptune in a 29 Day Orbit Around Very Metal Poor G Dwarf

The HARPS search for southern extra-solar planets. XXXIX. HD175607 b, the most metal-poor G dwarf with an orbiting sub-Neptune

Authors:

Mortier et al

Abstract:

Context.

The presence of a small-mass planet (Mp less than 0.1\,MJup) seems, to date, not to depend on metallicity, however, theoretical simulations have shown that stars with subsolar metallicities may be favoured for harbouring smaller planets. A large, dedicated survey of metal-poor stars with the HARPS spectrograph has thus been carried out to search for Neptunes and super-Earths.

Aims.

In this paper, we present the analysis of \object{HD175607}, an old G6 star with metallicity [Fe/H] = -0.62. We gathered 119 radial velocity measurements in 110 nights over a time span of more than nine years.

Methods.

The radial velocities were analysed using Lomb-Scargle periodograms, a genetic algorithm, a Markov chain Monte Carlo analysis, and a Gaussian processes analysis. The spectra were also used to derive stellar properties. Several activity indicators were analysed to study the effect of stellar activity on the radial velocities.

Results.

We find evidence for the presence of a small Neptune-mass planet (Mpsini=8.98±1.10\,M⊕) orbiting this star with an orbital period P=29.01±0.02\, days in a slightly eccentric orbit (e=0.11±0.08). The period of this Neptune is close to the estimated rotational period of the star. However, from a detailed analysis of the radial velocities together with the stellar activity, we conclude that the best explanation of the signal is indeed the presence of a planetary companion rather than stellar related. An additional longer period signal (P∼1400\,d) is present in the data, for which more measurements are needed to constrain its nature and its properties.

Conclusions.

HD 175607 is the most metal-poor FGK dwarf with a detected low-mass planet amongst the currently known planet hosts. This discovery may thus have important consequences for planet formation and evolution theories.

HD1461, HD40307 and HD204313 Exoplanetary Systems Reexamined by HARPS

The HARPS search for southern extra-solar planets. XXXVII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles

Authors:

Díaz et al

Abstract:

We present the analysis of the entire HARPS observations of three stars that host planetary systems: HD1461, HD40307, and HD204313. The data set spans eight years and contains more than 200 nightly averaged velocity measurements for each star. This means that it is sensitive to both long-period and low-mass planets and also to the effects induced by stellar activity cycles. We modelled the data using Keplerian functions that correspond to planetary candidates and included the short- and long-term effects of magnetic activity. A Bayesian approach was taken both for the data modelling, which allowed us to include information from activity proxies such as log(R′HK) in the velocity modelling, and for the model selection, which permitted determining the number of significant signals in the system. The Bayesian model comparison overcomes the limitations inherent to the traditional periodogram analysis. We report an additional super-Earth planet in the HD1461 system. Four out of the six planets previously reported for HD40307 are confirmed and characterised. We discuss the remaining two proposed signals. In particular, we show that when the systematic uncertainty associated with the techniques for estimating model probabilities are taken into account, the current data are not conclusive concerning the existence of the habitable-zone candidate HD40307 g. We also fully characterise the Neptune-mass planet that orbits HD204313 in 34.9 days.

M Dwarf Super Earth K2-3b is Rocky, Near Inner Edge of the Habitable Zone and has Two Other SuperEarths in System

A HARPS view on K2-3

Authors:

Almenara et al

Abstract:

K2 space observations recently found that three super-Earths transit the nearby M dwarf K2-3. The apparent brightness and the small physical radius of their host star rank these planets amongst the most favourable for follow-up characterisations. The outer planet orbits close to the inner edge of the habitable zone and might become one of the first exoplanets searched for biomarkers using transmission spectroscopy. We used the HARPS velocimeter to measure the mass of the planets. The mass of planet b is 8.4±2.1 M⊕, while our determination of those planets c and d are affected by the stellar activity. With a density of 4.32+2.0−0.76 gcm−3, planet b is probably mostly rocky, but it could contain up to 50% water.

Hot Saturn Kelt-6b has a Sister Exoplanet Gas Giant

The GAPS Programme with HARPS-N@TNG X. The multi-planet system KELT-6: detection of the planet KELT-6 c and measurement of the Rossiter-McLaughlin effect for KELT-6 b

Authors:

Damasso et al

Abstract:

Aims.

For more than 1.5 years we monitored spectroscopically the star KELT-6 (BD+312447), known to host the transiting hot Saturn KELT-6b, because a previously observed long-term trend in radial velocity time series suggested the existence of an outer companion.

Methods.

We collected a total of 93 new spectra with the HARPS-N and TRES spectrographs. A spectroscopic transit of KELT-6b was observed with HARPS-N, and simultaneous photometry was obtained with the IAC-80 telescope.

Results.

We proved the existence of an outer planet with a mininum mass Mpsini=3.71±0.21 MJup and a moderately eccentric orbit (e=0.21+0.039−0.036) of period P∼3.5 years. We improved the orbital solution of KELT-6b and obtained the first measurement of the Rossiter-McLaughlin effect, showing that the planet has a likely circular, prograde, and slightly misaligned orbit, with a projected spin-orbit angle λ=−36±11 degrees. We improved the KELT-6b transit ephemeris from photometry, and we provided new measurements of the stellar parameters. KELT-6 appears as an interesting case to study the formation and evolution of multi-planet systems.

Magnetic Activity and Asteroseismology of τ Bootis A

The GAPS Programme with HARPS-N at TNG. VII. Putting exoplanets in the stellar context: magnetic activity and asteroseismology of τ Bootis A

Authors:

Borsa et al

Abstract:

Aims.

We observed the τ Boo system with the HARPS-N spectrograph to test a new observational strategy aimed at jointly studying asteroseismology, the planetary orbit, and star-planet magnetic interaction.

Methods.

We collected high-cadence observations on 11 nearly consecutive nights and for each night averaged the raw FITS files using a dedicated software. In this way we obtained spectra with a high signal-to-noise ratio, used to study the variation of the CaII H&K lines and to have radial velocity values free from stellar oscillations, without losing the oscillations information. We developed a dedicated software to build a new custom mask that we used to refine the radial velocity determination with the HARPS-N pipeline and perform the spectroscopic analysis.

Results.

We updated the planetary ephemeris and showed the acceleration caused by the stellar binary companion. Our results on the stellar activity variation suggest the presence of a high-latitude plage during the time span of our observations. The correlation between the chromospheric activity and the planetary orbital phase remains unclear. Solar-like oscillations are detected in the radial velocity time series: we estimated asteroseismic quantities and found that they agree well with theoretical predictions. Our stellar model yields an age of 0.9±0.5 Gyr for τ Boo and further constrains the value of the stellar mass to 1.38±0.05 M⊙.

Sodium Detected in HD 189733b's Atmosphere

Spectrally resolved detection of sodium in the atmosphere of HD189733b with the HARPS spectrograph

Authors:

Wyttenbach et al

Abstract:

Atmospheric properties of exoplanets can be constrained with transit spectroscopy. The signature of atomic sodium NaI, known to be present above the clouds, is a powerful probe of the upper atmosphere, where it can be best detected and characterized at high spectral resolution. Our goal is to obtain a high-resolution transit spectrum of HD189733b in the region around the resonance doublet of NaI at 589 nm, to characterize the absorption signature previously detected from space at low resolution. We analyze archival transit data of HD189733b obtained with the HARPS spectrograph. We retrieve the transit spectrum and light curve of the planet, implementing corrections for telluric contamination and planetary orbital motion. We spectrally resolve the NaI D doublet and measure line contrasts of 0.64±0.07% (D2) and 0.40±0.07% (D1) and FWHMs of $0.52\pm0.08~\AA$. This corresponds to a detection at the 10-σ level of excess of absorption of 0.32±0.03% in a passband of $2\times0.75\ \AA$ centered on each line. We derive temperatures of 2600±600 K and 3270±330 K at altitudes of 9800±2800 km and 12700±2600 km in the NaI D1 and D2 line cores, respectively. We measure a temperature gradient of ∼0.2 K km−1 from comparison with theoretical models. We also detect a blueshift of $0.16\pm0.04\ \AA$ (4 σ) in the line positions. This blueshift may be due to winds blowing at 8±2 km s−1 in the upper layers of the atmosphere. We demonstrate the relevance of studying exoplanet atmospheres with high-resolution spectrographs mounted on 4-meter-class telescopes. Our results pave the way towards in-depth characterization of physical conditions in the atmospheres of many exoplanetary systems with future spectrographs such as ESPRESSO on the VLT or HiReS and METIS on the E-ELT.

Six Exoplanets Giant Exoplanets & One Brown Dwarf Parameters Improved

Improved parameters of seven Kepler giant companions characterized with SOPHIE and HARPS-N 

Authors:

Bonomo et al

Abstract:

Radial-velocity observations of Kepler candidates obtained with the SOPHIE and HARPS-N spectrographs have permitted unveiling the nature of the five giant planets Kepler-41b, Kepler-43b, Kepler-44b, Kepler-74b, and Kepler-75b, the massive companion Kepler-39b, and the brown dwarf KOI-205b. These companions were previously characterized with long-cadence (LC) Kepler data. Here we aim at refining the parameters of these transiting systems by i) modelling the published radial velocities (RV) and Kepler short-cadence (SC) data that provide a much better sampling of the transits, ii) performing new spectral analyses of the SOPHIE and ESPaDOnS spectra, and iii) improving stellar rotation periods hence stellar age estimates through gyrochronology, when possible. Posterior distributions of the system parameters were derived with a differential evolution Markov chain Monte Carlo approach. Our main results are as follows: a) Kepler-41b is significantly larger and less dense than previously found because a lower orbital inclination is favoured by SC data. This also affects the determination of the geometric albedo that is lower than previously derived: Ag less than 0.135; b) Kepler-44b is moderately smaller and denser than reported in the discovery paper; c) good agreement was achieved with published Kepler-43, Kepler-75, and KOI-205 system parameters, although the host stars Kepler-75 and KOI-205 were found to be slightly richer in metals and hotter, respectively; d) the previously reported non-zero eccentricities of Kepler-39b and Kepler-74b might be spurious. If their orbits were circular, the two companions would be smaller and denser than in the eccentric case. The radius of Kepler-39b is still larger than predicted by theoretical isochrones. Its parent star is hotter and richer in metals than previously determined.

GJ 3293 and GJ 3341 Exoplanetary Systems: Two Neptunes and a SuperEarth

The HARPS search for southern extra-solar planets XXXV. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543

Authors:

Astudillo-Defru et al

Abstract:

Context.

Planetary companions of a fixed mass induce larger amplitude reflex motions around lower-mass stars, which helps make M dwarfs excellent targets for extra-solar planet searches. State of the art velocimeters with ∼1m/s stability can detect very low-mass planets out to the habitable zone of these stars. Low-mass, small, planets are abundant around M dwarfs, and most known potentially habitable planets orbit one of these cool stars.

Aims.

Our M-dwarf radial velocity monitoring with HARPS on the ESO 3.6m telescope at La Silla observatory makes a major contribution to this sample.

Methods.

We present here dense radial velocity (RV) time series for three M dwarfs observed over ∼5 years: GJ 3293 (0.42M⊙), GJ 3341 (0.47M⊙), and GJ 3543 (0.45M⊙). We extract those RVs through minimum χ2 matching of each spectrum against a high S/N ratio stack of all observed spectra for the same star. We then vet potential orbital signals against several stellar activity indicators, to disentangle the Keplerian variations induced by planets from the spurious signals which result from rotational modulation of stellar surface inhomogeneities and from activity cycles.

Results.

Two Neptune-mass planets - msin(i)=1.4±0.1 and 1.3±0.1Mnept - orbit GJ 3293 with periods P=30.60±0.02 d and P=123.98±0.38 d, possibly together with a super-Earth - msin(i)∼7.9±1.4M⊕ - with period P=48.14±0.12d. A super-Earth - msin(i)∼6.1M⊕ - orbits GJ 3341 with P=14.207±0.007d. The RV variations of GJ 3543, on the other hand, reflect its stellar activity rather than planetary signals.

KOI-188b, KOI-195b, KOI-192b, and KOI-830b: 3 New Hot Saturns and a Hot Jupiter

Characterization of the four new transiting planets KOI-188b, KOI-195b, KOI-192b, and KOI-830b

Authors:

Hebrard et al

Abstract:

The characterization of four new transiting extrasolar planets is presented here. KOI-188b and KOI-195b are bloated hot Saturns, with orbital periods of 3.8 and 3.2 days, and masses of 0.25 and 0.34 M_Jup, respectively. They are located in the low-mass range of known transiting, giant planets. KOI-192b has a similar mass (0.29 M_Jup) but a longer orbital period of 10.3 days. This places it in a domain where only few planets are known. KOI-830b, finally, with a mass of 1.27 M_Jup and a period of 3.5 days, is a typical hot Jupiter. The four planets have radii of 0.98, 1.09, 1.2, and 1.08 R_Jup, respectively. We detected no significant eccentricity in any of the systems, while the accuracy of our data does not rule out possible moderate eccentricities. The four objects were first identified by the Kepler Team as promising candidates from photometry of the Kepler satellite. We establish here their planetary nature thanks to the radial velocity follow-up we secured with the HARPS-N spectrograph at the Telescopio Nazionale Galileo. The combined analyses of the whole datasets allow us to fully characterize the four planetary systems. These new objects increase the number of well-characterized exoplanets for statistics, and provide new targets for individual follow-up studies. The pre-screening we performed with the SOPHIE spectrograph at the Observatoire de Haute-Provence as part of that study also allowed us to conclude that a fifth candidate, KOI-219.01, is not a planet but is a false positive.

Kepler-101 System has a hot Saturn and hot SuperEarth

Characterization of the Kepler-101 planetary system with HARPS-N. A hot super-Neptune with an Earth-sized low-mass companion

Authors:

Bonomo et al

Abstract:

We report on the characterization of the Kepler-101 planetary system, thanks to a combined DE-MCMC analysis of Kepler data and forty radial velocities obtained with the HARPS-N spectrograph. This system was previously validated by Rowe et al. (2014) and is composed of a hot super-Neptune, Kepler-101b, and an Earth-sized planet, Kepler-101c. These two planets orbit the slightly evolved and metal-rich G-type star in 3.49 and 6.03 days, respectively. With mass Mp=51.1+5.1−4.7 M⊕, radius Rp=5.77+0.85−0.79 R⊕, and density ρp=1.45+0.83−0.48gcm−3, Kepler-101b is the first fully-characterized super-Neptune, and its density suggests that heavy elements make up a significant fraction of its interior; more than 60% of its total mass. Kepler-101c has a radius of 1.25+0.19−0.17 R⊕, which implies the absence of any H/He envelope, but its mass could not be determined due to the relative faintness of the parent star for highly precise radial-velocity measurements (Kp=13.8) and the limited number of radial velocities. The 1 σ upper limit, Mp less than 3.8 M⊕, excludes a pure iron composition with a 68.3% probability. The architecture of the Kepler-101 planetary system - containing a close-in giant planet and an outer Earth-sized planet with a period ratio slightly larger than the 3:2 resonance - is certainly of interest for planet formation and evolution scenarios. This system does not follow the trend, seen by Ciardi et al. (2013), that in the majority of Kepler systems of planet pairs with at least one Neptune-size or larger planet, the larger planet has the longer period.

New Obervations of 55 Cnc e

Rossiter-McLaughlin Observations of 55 Cnc e

Authors:

Lopez-Morales et al

Abstract:

We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between January 2012 and November 2013 with HARPS and HARPS-N. We detect no radial-velocity signal above 35 cm/s (3-sigma) and confine the stellar v sin i to 0.2 +/- 0.5 km/s. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths.

Revisiting the Kepler-10 System: Is Kepler-10c the First Giant ROCKY Planet? Or a Stripped Gas Giant?

The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet

Authors:

Dumusque et al

Abstract:

Kepler-10b was the first rocky planet detected by the Kepler satellite and con- firmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was sta- tistically validated, but the radial velocities were only good enough to set an upper limit of 20 Mearth for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In to- tal, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determina- tion for Kepler-10b to 15%. With a mass of 3.33 +/- 0.49 Mearth and an updated radius of 1.47 +0.03 -0.02 Rearth, Kepler-10b has a density of 5.8 +/- 0.8 g cm-3, very close to the value -0.02 predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 +/- 1.9 Mearth and radius of 2.35 +0.09 -0.04 Rearth, -0.04 Kepler-10c has a density of 7.1 +/- 1.0 g cm-3. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods.

Or HD 41248 Does *NOT* Have Exoplanets

The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?

Authors:

Santos et al

Abstract:

The search for planets orbiting metal-poor stars is of uttermost importance for our understanding of the planet formation models. However, no dedicated searches have been conducted so far for very low mass planets orbiting such objects. Only a few cases of low mass planets orbiting metal-poor stars are thus known. Amongst these, HD41248 is a metal-poor, solar-type star on which a resonant pair of super-Earth like planets has In the present paper we present a new planet search program that is using the HARPS spectrograph to search for Neptunes and Super-Earths orbiting a sample of metal-poor FGK dwarfs. We then present a detailed analysis of an additional 162 radial velocity measurements of HD41248, obtained within this program, with the goal of confirming the existence of the proposed planetary system. We analyzed the precise radial velocities, obtained with the HARPS spectrograph, together with several stellar activity diagnostics and line profile indicators. A careful analysis shows no evidence for the planetary system previously announced. One of the signals, with a period of about 25 days, is shown to be related to the rotational period of the star, and is clearly seen in some of the activity proxies. The remaining signal (P~18 days) could not be convincingly retrieved in the new data set. We discuss possible causes for the complex (evolving) signals observed in the data of HD41248, proposing that they may be explained by the appearance and disappearance of active regions on the surface of a star with strong differential rotation, or by a combination of the sparse data sampling and active region evolution.

Earth's Signature as a Transiting Exoplanet & E-ELT Will be Able to Detect Biogenic Exoatmospheres out to 10 Parsecs

The Earth as an extrasolar transiting planet - II: HARPS and UVES detection of water vapour and biogenic species O2 and O3

Authors:

Arnold et al

Abstract:

The atmospheric composition of transiting exoplanets can be characterized during transit by spectroscopy. For an Earth twin, models predict that oxygen and ozone biogenic gases should be detectable, as well as water vapour, a molecule linked to habitability as we know it on Earth. The aim is to measure the Earth radius versus wavelength at the highest spectral resolution available to fully characterize the signature of the Earth seen as a transiting exoplanet. We present observations of Dec. 21, 2010 Moon eclipse. The Earth observed from the Moon during a lunar eclipse transits in front of the Sun and opens access to the Earth atmosphere transmission spectrum. We used two different ESO spectrographs to take penumbra and umbra high-resolution spectra from 3100 to 10400\AA. A change in moisture above the telescope compromised the UVES data. We explain how we correct this effect. The data are analyzed by three different methods, the first method being the method described in Vidal-Madjar et al. 2010 based on the analysis of pairs of penumbra spectra. The second makes use of a single penumbra spectrum, and the third of all penumbra and umbra spectra. Profiles are obtained with the three methods for both instruments. The first method gives the best result, in agreement with a model. The second method seems more sensitive to the Doppler shift of solar spectral lines with respect to the telluric lines. The third method makes use of umbra spectra that bias the result by increasing the overall negative slope of the profile. It can be corrected a posteriori from results with the first method. The three methods clearly show the spectral signature of the Rayleigh scattering in the Earth atmosphere and the bands of H2O, O2 and O3. Sodium is detected. Finally we show that the E-ELT will be able to detect the O2 A-band, and O3 and water vapour to a lesser extent, for an Earth twin at 10pc.

EXPRESSO Instrument Will be Deployed in 2016 to Follow-on to HARPS

ESPRESSO: The next European exoplanet hunter

Authors:

Pepe et al

Abstract:

The acronym ESPRESSO stems for Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations; this instrument will be the next VLT high resolution spectrograph. The spectrograph will be installed at the Combined-Coud\'e Laboratory of the VLT and linked to the four 8.2 m Unit Telescopes (UT) through four optical Coud\'e trains. ESPRESSO will combine efficiency and extreme spectroscopic precision. ESPRESSO is foreseen to achieve a gain of two magnitudes with respect to its predecessor HARPS, and to improve the instrumental radial-velocity precision to reach the 10 cm/s level. It can be operated either with a single UT or with up to four UTs, enabling an additional gain in the latter mode. The incoherent combination of four telescopes and the extreme precision requirements called for many innovative design solutions while ensuring the technical heritage of the successful HARPS experience. ESPRESSO will allow to explore new frontiers in most domains of astrophysics that require precision and sensitivity. The main scientific drivers are the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby G to M-dwarfs and the analysis of the variability of fundamental physical constants. The project passed the final design review in May 2013 and entered the manufacturing phase. ESPRESSO will be installed at the Paranal Observatory in 2016 and its operation is planned to start by the end of the same year.

GJ 221d: a new SubSaturn Exoplanet 66 Light Years Away

A new cold sub-Saturnian candidate planet orbiting GJ 221

Authors:

Tuomi et al

Abstract:

We re-analyse the recently published HARPS and PFS velocities of the nearby K dwarf GJ 221 that have been reported to contain the signatures of two planets orbiting the star. Our goal is to see whether the earlier studies discussing the system fell victims of false negative detections. We perform the analyses by using an independent statistical method based on posterior samplings and model comparisons in the Bayesian framework that is known to be more sensitive to weak signals of low-mass planets. According to our analyses, we find strong evidence in favour of a third candidate planet in the system corresponding to a cold sub-Saturnian planet with an orbital period of 500 days and a minimum mass of 29 M⊕. Application of sub-optimal signal detection methods can leave low-amplitude signals undetected in radial velocity time-series. Our results suggest that the estimated statistical properties of low-mass planets can thus be biased because several signals corresponding to low-mass candidate planets may have gone unnoticed. This also suggests that the occurrence rates of such planets based on radial velocity surveys might be underestimated.