In the frame of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the detection of a giant planet around the young F-type star HD113337. We estimated the age of the system to be 150^+100^_-50_Myr. Interestingly, an IR excess attributed to a cold debris disk was previously detected on this star. The SOPHIE spectrograph on the 1.93m telescope at the Observatoire de Haute-Provence (OHP) was used to obtain ~300 spectra over 6 years. We used our SAFIR tool, dedicated to the spectra analysis of A and F stars, to derive the radial velocity variations. The data reveal a 324.0^+1.7^_-3.3_days period that we attribute to a giant planet with a minimum mass of 2.83+/-0.24MJup in an eccentric orbit with e=0.46+/-0.04. A long-term quadratic drift, that we assign to be probably of stellar origin, is superimposed to the Keplerian solution.
We conducted a 5-night observing run with the spectrometer HARPS at the ESO 3.6-m telescope in August 2006. We selected the 4th magnitude F8V star HD 203608, a low-metallicity star of the old galactic disk. We reduced the spectra with the on-line data reduction software provided by the instrument. We developed a new statistical approach for extracting the significant peaks in the Fourier domain.
We have used high-cadence radial velocity measurements from the Hobby-Eberly Telescope with published velocities from the Lick 3 m Shane Telescope, combined with astrometric data from the Hubble Space Telescope (HST) Fine Guidance Sensors to refine the orbital parameters of the HD 128311 system, and determine an inclination of 55.95{deg}+/-14.55{deg} and true mass of 3.789_-0.432_^+0.924^ M_JUP_ for HD 128311 c. The combined radial velocity data also reveal a short period signal which could indicate a third planet in the system with an Msin i of 0.133+/-0.005 M_JUP_or stellar phenomena. Photometry from the T12 0.8 m automatic photometric telescope at the Fairborn Observatory and HST are used to determine a photometric period close to, but not within the errors of the radial velocity signal. We performed a cross-correlation bisector analysis of the radial velocity data to look for correlations with the photometric period and found none. Dynamical integrations of the proposed system show long-term stability with the new orbital parameters of over 10 million years. Our new orbital elements do not support the claims of HD 128311 b and c being in mean motion resonance.
With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. This wide diversity provides fundamental clues to the processes of planet formation and evolution. We present a full investigation of the HD 219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD 219828. The spectra were used to characterise the star and its chemical abundances, as well as to check for spurious, activity induced signals. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1-years) massive (msini=15.1M_{Jup}_) companion (HD 219828 c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD 219828 b, with a minimum mass of 21M_{sun}_ and a period of 3.83-days. The dynamical analysis shows that the system is stable, and that the equilibrium eccentricity of planet $b$ is close to zero. The HD 219828 system is extreme and unique in several aspects. First, ammong all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD 219828, with a hot neptune and a long-period massive companion are more frequent than similar systems with a hot jupiter instead. This suggests that the formation of hot neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD 219828 c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD 219828 b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD 219828 c may become a benchmark object for the range in between giant planets and brown dwarfs.
We report the discovery of a planetary system around HD 9446, performed from radial velocity measurements secured with the spectrograph SOPHIE at the 193-cm telescope of the Haute-Provence Observatory for more than two years. At least two planets orbit this G5V, active star: HD 9446b has a minimum mass of 0.7M_Jup_ and a slightly eccentric orbit with a period of 30-days, whereas HD 9446c has a minimum mass of 1.8M_Jup_ and a circular orbit with a period of 193-days. As for most of the known multiple planet systems, the HD 9446-system presents a hierarchical disposition with a massive outer planet and a lighter inner planet.
We report on the discovery of a substellar companion or a massive Jupiter orbiting the G5V star HD 16760 using the spectrograph SOPHIE installed on the OHP 1.93-m telescope. Characteristics and performances of the spectrograph are presented, as well as the SOPHIE exoplanet consortium program. With a minimum mass of 14.3M_{Jup}_, an orbital period of 465 days and an eccentricity of 0.067, HD 16760b seems to be located just at the end of the mass distribution of giant planets, close to the planet/brown-dwarf transition. Its quite circular orbit supports a formation in a gaseous protoplanetary disk.
We present a new set of radial-velocity measurements of the spectroscopic binary star HD 165052 obtained by disentangling of high-resolution optical spectra. The longitude of the periastron ({varpi}=60+/-2{deg}) shows a variation with respect to previous studies. We have determined the apsidal motion rate of the system {dot{varpi}}=12.1+/-0.3{deg}/yr, which was used to calculate the absolute masses of the binary components: M_1_=22.5+/-1.0M_{sun}_ and M_2_=20.5+/-0.9M_{sun}_. Analysing the separated spectra we have re-classified the components as O7Vz and O7.5Vz stars.
HD 126516 radial velocity & photometric observations
Short Name:
J/AJ/158/189
Date:
21 Oct 2021
Publisher:
CDS
Description:
From numerous radial velocities as well as Johnson B and V differential photoelectric photometry, we have determined the orbital elements and other properties of the single-lined triple system HD 126516. This system consists of a narrow-lined F5 V star and an unseen M dwarf companion in a 2.1241 day circular orbit. The small, low-mass secondary produces detectable eclipses of the primary, and that pair has been given the variable star name V349 Vir. Variations of the center-of-mass velocity of this short-period system have an orbital period of 702.7 days or 1.92 yr and an eccentricity of 0.36. The third star is likely a K or M dwarf. From an analysis of our photometry, we conclude that the primary of HD 126516 is not a {gamma} Dor variable. Comparison with evolutionary tracks indicates that the primary is slightly metal-poor and has an age of 2.5 Gyr. The projected rotational velocity of the primary is very low, just 4 km/s, which is 10 times less than its synchronous rotational velocity. Thus, either that component's rotation is extremely non-synchronous or the inclinations of the rotational and orbital axes are very different, and so the primary has a very large spin-orbit misalignment. Because of the moderate age of the system and the fact that its orbit is already circularized, neither situation is expected theoretically.
The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti-type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in four separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. Frequency Analysis was performed using Period04. The spectral analysis was performed using equivalent widths and spectral synthesis. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group were determined and are related to l=0 and l=1 p-modes. Evidence for amplitude modulation of the frequencies in two groups is seen. The effective temperature (Teff) was derived to be 8600+/-200K, logg is 4.1+/-0.2, and the projected rotational velocity (vsini) is 53+/-1km/s. Using our Teff value and the radius of 1.8+/-0.5R_{sun}_ derived from spectral energy distribution (SED) fitting, we get a luminosity logL/L_{sun}_ of 1.20+/-0.14 which agrees well to the seismologically determined values of 1.65 Rsun and, hence, a logL/L_{sun}_ of 1.13. The radial velocity of 14+/-2km/s we derived for HD 261711, confirms the star's membership to NGC 2264. Our asteroseismic models suggest that HD 261711 is a delta Scuti-type star close to the zero-age main sequence (ZAMS) with a mass of 1.8 to 1.9M_{sun}_. With an age of about 10 million years derived from asteroseismology, the star is either a young ZAMS star or a late PMS star just before the onset of hydrogen-core burning. The observed splittings about the l=0 and 1 parent modes may be an artifact of the Fourier derived spectrum of frequencies with varying amplitudes.
The presence of a small-mass planet (M_p_<0.1M_{Jup}_) 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. In this paper we present the analysis of HD175607, an old G6 star with metallicity [Fe/H]=-0.62. We gathered 119 radial velocity measurements in 110 nights over a timespan of more than 9 years. 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. We find evidence for the presence of a small Neptune-mass planet (M_p_sini=8.98+/-1.10M_{sun}_) orbiting this star with an orbital period P=29.01+/-0.02days 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 due to the presence of a planetary companion rather than stellar related. An additional longer period signal (P~1400d) is present in the data, for which more measurements are needed to constrain its nature and its properties. HD175607 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.