The CoRoT satellite has provided high-precision photometric light curves for more than 163,000 stars and found several hundreds of transiting systems compatible with a planetary scenario. If ...ground-based velocimetric observations are the best way to identify the actual planets among many possible configurations of eclipsing binary systems, recent transit surveys have shown that it is not always within reach of the radial-velocity detection limits. In this paper, we present a transiting exoplanet candidate discovered by CoRoT whose nature cannot be established from ground-based observations, and where extensive analyses are used to validate the planet scenario. They are based on observing constraints from radial-velocity spectroscopy, adaptive optics imaging and the CoRoT transit shape, as well as from priors on stellar populations, planet and multiple stellar systems frequency. We use the fully Bayesian approach developed in the pastis (Planet Analysis and Small Transit Investigation Software) analysis software, and conclude that the planet scenario is at least 1400 times more probable than any other false-positive scenario. The primary star is a metallic solar-like dwarf, with ... and ... The validated planet has a radius of ... and mass less than 49 M... Its mean density is smaller than 2.56 g cm-3 and orbital period is 9.7566 ± 0.0012 d. This object, called CoRoT-22 b, adds to a large number of validated Kepler planets. These planets do not have a proper measurement of the mass but allow statistical characterization of exoplanets population. (ProQuest: ... denotes formulae/symbols omitted.)
We report the discovery from K2 of two transiting hot Jupiter systems. K2-295 (observed in Campaign 8) is a K5 dwarf which hosts a planet slightly smaller than Jupiter, orbiting with a period of 4.0 ...d. We have made an independent discovery of K2-237 b (Campaign 11), which orbits an F9 dwarf every 2.2 d and has an inflated radius 60-70% larger than that of Jupiter. We use high-precision radial velocity measurements, obtained using the HARPS and FIES spectrographs, to measure the planetary masses. We find that K2-295 b has a similar mass to Saturn, while K2-237 b is a little more massive than Jupiter.
Context. Studies of transiting extrasolar planets are of key importance for understanding the nature of planets outside our solar system because their masses, diameters, and bulk densities can be ...measured. An important part of transit-search programmes is the removal of false-positives. In the case of the CoRoT space mission, the majority of the false-positives are removed by a detailed analysis of the light curves and by seeing-limited imaging in- and out-of-transit. However, the critical question is how many of the candidates that passed all these tests are false-positives. Such false-positives can be caused by eclipsing binaries, which are either related or unrelated to the targets. Aims. For our study we selected 25 CoRoT candidates that have already been screened against false-positives using detailed analysis of the light curves and seeing-limited imaging, which has transits that are between 0.7 and 0.05% deep. Our aim is to search for companion candidates that had not been recognized in previous observations. Methods. We observed 20 candidates with the adaptive optics imager NaCo and 18 with the high-resolution infrared spectrograph CRIRES. Results. We found previously unknown stars within 2′′ of the targets in seven of the candidates. All of these are too faint and too close to the targets to have been previously detected with seeing-limited telescopes in the optical. Our study thus leads to the surprising results that if we remove all candidates excluded by the sophisticated analysis of the light-curve, as well as carrying out deep imaging with seeing-limited telescopes, still 28−35% of the remaining candidates are found to possess companions that are bright enough to be false-positives. Conclusions. Given that the companion candidates cluster around the targets and that the J − K colours are consistent with physical companions, we conclude that the companion candidates are more likely to be physical companions rather than unrelated field stars.
We measure the angle between the planetary orbit and the stellar rotation axis in the transiting planetary system CoRoT-1, with new HIRES/Keck and FORS/VLT high-accuracy photometry. The data indicate ...a highly tilted system, with a projected spin-orbit angle λ= 77°± 11°. Systematic uncertainties in the radial velocity data could cause the actual errors to be larger by an unknown amount, and this result needs to be confirmed with further high-accuracy spectroscopic transit measurements. Spin-orbit alignment has now been measured in a dozen extra-solar planetary systems, and several show strong misalignment. The first three misaligned planets were all much more massive than Jupiter and followed eccentric orbits. CoRoT-1, however, is a jovian-mass close-in planet on a circular orbit. If its strong misalignment is confirmed, it would break this pattern. The high occurrence of misaligned systems for several types of planets and orbits favours planet–planet scattering as a mechanism to bring gas giants on very close orbits.
CoRoT-21, a F8IV star of magnitude V = 16 mag, was observed by the space telescope CoRoT during the Long Run 01 (LRa01) in the first winter field (constellation Monoceros) from October 2007 to March ...2008. Transits were discovered during the light curve processing. Radial velocity follow-up observations, however, were performed mainly by the 10-m Keck telescope in January 2010. The companion CoRoT-21b is a Jupiter-like planet of 2.26 ± 0.33 Jupiter masses and 1.30 ± 0.14 Jupiter radii in an circular orbit of semi-major axis 0.0417 ± 0.0011 AU and an orbital period of 2.72474 ± 0.00014 days. The planetary bulk density is (1.36 ± 0.48) × 10SUP3/SUP kg mSUP-3/SUP, very similar to the bulk density of Jupiter, and follows an MSUP1/3/SUP - R relation like Jupiter. The F8IV star is a sub-giant star of 1.29 ± 0.09 solar masses and 1.95 ± 0.2 solar radii. The star and the planet exchange extremetidal forces that will lead to orbital decay and extreme spin-up of the stellar rotation within 800 Myr if the stellar dissipation is QSUB∗/SUB/kSUB2∗/SUB ≤ 10SUP7/SUP. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain.
ι Dra (HIP 75458) is a well-known example of a K giant hosting a substellar companion. We present radial velocity measurements of this star from observations taken with three different instruments ...spanning nearly 8 years. They show more clearly that the RV period is long-lived and coherent thus supporting the companion hypothesis. The longer time baseline now allows for a more accurate determination of the orbit with a revised period of $P=511\,$d and an additional small linear trend, indicative of another companion in a wide orbit. Moreover we show that the star exhibits low amplitude, solar-like oscillations with frequencies around 3–4${\,{\rm d}^{-1} }$(34.7–46.3 μHz).
We have performed radial velocity (RV) monitoring of the components of the binary system HD 106515 over almost 11 years using the high-resolution spectrograph SARG at Telescopio Nazionale Galileo ...(TNG). The primary shows long-period radial velocity variations that indicate the presence of a low-mass companion whose projected mass is in the planetary regime (msini = 9.33 MJ). The 9.8 year orbit is quite eccentric (e = 0.57), as is typical for massive giant planets. Our results confirm the previously made preliminary announcement of the planet by Mayor et al. (2011, A&A, submitted arXiv:1109.2497). The secondary instead does not show significant RV variations. The two components do not differ significantly in chemical composition, as was also found for other pairs of which one component hosts giant planets. Adaptive optics images obtained with TNG/AdOpt do not reveal additional stellar companions. From the analysis of the relative astrometry of the components of the wide pair we compute an upper limit on the mass of the newly detected companion of about 0.25 M⊙. State-of-the-art or near-future instrumentation can provide true mass determination, thanks to the availability of the wide companion HD106515B as reference. Therefore, HD 106515Ab will allow a deeper insight into the transition region between planets and brown dwarfs.
We present iron abundance analysis for 23 wide binaries with main sequence components in the temperture range 4900–6300 K, taken from the sample of the pairs currently included in the radial velocity ...planet search on going at the Telescopio Nazionale Galileo (TNG) using the high resolution spectrograph SARG. The use of a line-by-line differential analysis technique between the components of each pair allows us to reach errors of about 0.02 dex in the iron content difference. Most of the pairs have abundance differences lower than 0.02 dex and there are no pairs with differences larger than 0.07 dex. The four cases of differences larger than 0.02 dex may be spurious because of the larger error bars affecting pairs with large temperature difference, cold stars and rotating stars. The pair HD 219542, previously reported by us to have a different composition, here is shown to be normal. For non-rotating stars warmer than 5500 K, characterized by a thinner convective envelope and for which our analyis appears to be of higher accuracy, we are able to exclude in most cases the consumption of more than 1 Earth Mass of iron (about 5 Earth masses of meteoritic material) during the main sequence lifetime of the stars, placing more stringent limits (about 0.4 Earth masses of iron) in five cases of warm stars. This latter limit is similar to the estimates of rocky material accreted by the Sun during its main sequence lifetime. Combining the results of the present analysis with those for the Hyades and Pleiades, we conclude that the hypothesis that pollution by planetary material is the only mechanism responsible for the highest metallicity of the stars with planets may be rejected at more than 99% level of confidence if the incidence of planets in these samples is as high as 8% and similar to the field stars included in current radial velocity surveys. However, the significance of this result drops considerably if the incidence of planets around stars in binary systems and clusters is less than a half of that around normal field stars.
We present an analysis of spectral line bisector variations for a few stars observed in the SARG high precision radial velocity planet survey, and discuss their relationship with differential radial ...velocities. The spectra we consider are the same used for determining radial velocities. The iodine cell lines employed in the measurement of radial velocities were removed before bisector analysis. The line bisectors were then computed from average absorption profiles obtained by cross correlation of the stellar spectra with a mask made from suitable lines of a solar catalog. Bisector velocity spans were then determined: errors in these quantities compare well with theoretical expectations based on resolution, S/N and line shape. The plot of bisector velocity span against radial velocity was studied to search for correlations between line asymmetries and radial velocity variations. A correlation was seen for HD 166435 due to stellar activity, and for HD 8071B due to spectral contamination by the companion. No correlation was seen for 51 Peg and ρ CrB, stars hosting planets. We conclude that this technique may be useful to separate radial velocity variations due to barycenter motion from spurious signals in spectra acquired with the iodine cell.
We present the first ground-based detection of sodium absorption in the transmission spectrum of an extrasolar planet. Absorption due to the atmosphere of the extrasolar planet HD 189733b is detected ...in both lines of the Na I doublet. High spectral resolution observations were taken of 11 transits with the High Resolution Spectrograph (HRS) on the 9.2 m Hobby-Eberly Telescope (HET). The Na I absorption in the transmission spectrum due to HD 189733b is (-67.2 plus or minus 20.7) x 10 super(-5) deeper in the "narrow" spectral band that encompasses both lines relative to adjacent bands. The 1 sigma error includes both random and systematic errors, and the detection is >3 sigma . This amount of relative absorption in Na I for HD 189733b is similar to 3 times larger than that detected for HD 209458b by Charbonneau et al. (2002) and indicates that these two hot Jupiters may have significantly different atmospheric properties.
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