- ID:
- ivo://CDS.VizieR/J/ApJ/818/34
- Title:
- Radial velocity monitoring of 5 FGK stars
- Short Name:
- J/ApJ/818/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of two new long-period giant planets orbiting the stars HD 95872 and HD 162004 ({psi}^1^ Dra B) by the McDonald Observatory planet search. The planet HD 95872b has a minimum mass of 4.6M_Jup_ and an orbital semimajor axis of 5.2AU. The giant planet {psi}^1^ Dra Bb has a minimum mass of 1.5M_Jup_ and an orbital semimajor axis of 4.4AU. Both of these planets qualify as Jupiter analogs. These results are based on over one and a half decades of precise radial velocity (RV) measurements collected by our program using the McDonald Observatory Tull Coude spectrograph at the 2.7m Harlan J. Smith Telescope. In the case of {psi}^1^ Dra B we also detect a long-term nonlinear trend in our data that indicates the presence of an additional giant planet, similar to the Jupiter-Saturn pair. The primary of the binary star system, {psi}^1^ Dra A, exhibits a very large amplitude RV variation due to another stellar companion. We detect this additional member using speckle imaging. We also report two cases --HD 10086 and HD 102870 ({beta} Virginis)-- of significant RV variation consistent with the presence of a planet, but that are probably caused by stellar activity, rather than reflexive Keplerian motion. These two cases stress the importance of monitoring the magnetic activity level of a target star, as long-term activity cycles can mimic the presence of a Jupiter-analog planet.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2798
- Title:
- Radial velocity monitoring of PG 1018-047
- Short Name:
- J/MNRAS/421/2798
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 50 per cent of all known hot subdwarf B stars (sdBs) reside in close (short-period) binaries, for which common-envelope ejection is the most likely formation mechanism. However, Han et al. (2002MNRAS.336..449H, 2003MNRAS.341..669H) predict that the majority of sdBs should form through stable mass transfer leading to long-period binaries. Determining orbital periods for these systems is challenging and while the orbital periods of ~100 short-period systems have been measured, there are no periods measured above 30d. As part of a large programme to characterize the orbital periods of sdB binaries and their formation history, we have found that PG 1018-047 has an orbital period of 759.8+/-5.8d, easily making it the longest period ever detected for a sdB binary. Exploiting the Balmer lines of the subdwarf primary and the narrow absorption lines of the companion present in the spectra, we derive the radial velocity amplitudes of both stars, and estimate the mass ratio M_MS_/M_sdB_=1.6+/-0.2. From the combination of visual and infrared photometry, the spectral type of the companion star is determined to be mid-K.
- ID:
- ivo://CDS.VizieR/J/AJ/160/114
- Title:
- Radial velocity monitoring of TOI-421
- Short Name:
- J/AJ/160/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-141137, TIC94986319), a bright (V=9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421b, has an orbital period of Pb=5.19672{+/-}0.00049days, a mass of Mb=7.17{+/-}0.66M{Earth}, and a radius of Rb=2.68_-0.18_^+0.19^R{Earth}, whereas the outer warm Neptune, TOI-421c, has a period of Pc=16.06819{+/-}0.00035days, a mass of Mc=16.42_-1.04_^+1.06^M{Earth}, a radius of Rc=5.09_-0.15_^+0.16^R{Earth}, and a density of {rho}c=0.685_-0.072_^+0.080^g/cm^3^. With its characteristics, the outer planet ({rho}c=0.685_-0.072_^+0.080^g/cm^3^) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421b and TOI-421c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly{alpha} transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421c if equilibrium chemistry is assumed.
- ID:
- ivo://CDS.VizieR/J/AJ/157/52
- Title:
- Radial velocity observations in super-Earth systems
- Short Name:
- J/AJ/157/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use radial velocity (RV) observations to search for long-period gas giant companions in systems hosting inner super-Earth (1-4 R_{Earth}_, 1-10 M_{Earth}_) planets to constrain formation and migration scenarios for this population. We consistently refit published RV data sets for 65 stars and find nine systems with statistically significant trends indicating the presence of an outer companion. We combine these RV data with AO images to constrain the masses and semi-major axes of these companions. We quantify our sensitivity to the presence of long-period companions by fitting the sample with a power-law distribution and find an occurrence rate of 39%+/-7% for companions 0.5-20 M_Jup_ and 1-20 au. Half of our systems were discovered by the transit method, and half were discovered by the RV method. While differences in the RV baselines and number of data points between the two samples lead to different sensitivities to distant companions, we find that occurrence rates of gas giant companions in each sample are consistent at the 0.5{sigma} level. We compare the frequency of Jupiter analogs in these systems to the equivalent rate from field star surveys and find that Jupiter analogs are more common around stars hosting super-Earths. We conclude that the presence of outer gas giants does not suppress the formation of inner super-Earths, and that these two populations of planets instead appear to be correlated. We also find that the stellar metallicities of systems with gas giant companions are higher than those without companions, in agreement with the well-established metallicity correlation from RV surveys of field stars.
- ID:
- ivo://CDS.VizieR/J/A+A/442/1023
- Title:
- Radial velocity of 17 bright subdwarf B stars
- Short Name:
- J/A+A/442/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity curves for 15 bright subdwarf B binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. In addition, two bright sdB stars are discovered to be radial velocity variable but the period could not yet be determined. The companions for all systems are unseen.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A122
- Title:
- Radial-velocity of CARMENES M dwarfs
- Short Name:
- J/A+A/614/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous simulations predicted the activity-induced radial-velocity (RV) variations of M dwarfs to range from ~1cm/s to ~1km/s, depending on various stellar and activity parameters. We investigate the observed relations between RVs, stellar activity, and stellar parameters of M dwarfs by analyzing CARMENES high-resolution visual-channel spectra (0.5-1um), which were taken within the CARMENES RV planet survey during its first 20 months of operation. During this time, 287 of the CARMENES- sample stars were observed at least five times. From each spectrum we derived a relative RV and a measure of chromospheric Halpha emission. In addition, we estimated the chromatic index (CRX) of each spectrum, which is a measure of the RV wavelength dependence. Despite having a median number of only 11 measurements per star, we show that the RV variations of the stars with RV scatter of >10m/s and a projected rotation velocity vsini>2km/s are caused mainly by activity. We name these stars 'active RV-loud stars' and find their occurrence to increase with spectral type: from ~3% for early-type M dwarfs (M0.0-2.5V) through ~30% for mid-type M dwarfs (M3.0-5.5V) to >50% for late-type M dwarfs (M6.0-9.0V). Their RV-scatter amplitude is found to be correlated mainly with vsini. For about half of the stars, we also find a linear RV-CRX anticorrelation, which indicates that their activity-induced RV scatter is lower at longer wavelengths. For most of them we can exclude a linear correlation between RV and Halpha emission. Our results are in agreement with simulated activity-induced RV variations in M dwarfs. The RV variations of most active RV-loud M dwarfs are likely to be caused by dark spots on their surfaces, which move in and out of view as the stars rotate.
- ID:
- ivo://CDS.VizieR/J/A+A/448/697
- Title:
- Radial velocity of gamma Pegasi
- Short Name:
- J/A+A/448/697
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High resolution and high signal to noise ratio spectroscopic observations of the classical {beta} Cephei star {gamma} Peg were obtained between 1991 and 2005. The analysis of these data combined with previously published results shows that {gamma} Peg is a spectroscopic binary with an orbital period of 370.5d. We discovered three new frequencies in addition to the well-known 6.5897d^-1^ (0.15175d) one. That at 6.01d^-1^ is a typical Cephei frequency. The two others at 0.68 and 0.87d^-1^ are similar to the high degree g-mode frequencies found in SPB stars. Thus, {gamma} Peg is a hybrid {beta} Cephei-SPB star. Its position in the HR diagram is compatible with such a status. In addition, a small increase of the main period has been detected between the 1995 and 2005 observations.
- ID:
- ivo://CDS.VizieR/J/AJ/150/12
- Title:
- Radial velocity of HD 33643
- Short Name:
- J/AJ/150/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28+/-0.18M_J_, radius of 1.533^+0.046^_-0.047_R_J_, and an orbital period of 2.7347749+/-0.0000039days. The bright host star (HD33643; KELT-7) is an F-star with V=8.54, T_eff_=6789^+50^_-49_K, [Fe/H]=0.139^+0.075^_-0.081_, and logg=4.149+/-0.019. It has a mass of 1.535^+0.066^_-0.054_M_{Sun}_, a radius of 1.732^+0.043^_-0.045_R_{Sun}_, and is the fifth most massive, fifth hottest, and the ninth brightest star known to host a transiting planet. It is also the brightest star around which Kilodegree Extremely Little Telescope (KELT) has discovered a transiting planet. Thus, KELT-7b is an ideal target for detailed characterization given its relatively low surface gravity, high equilibrium temperature, and bright host star. The rapid rotation of the star (73+/-0.5km/s) results in a Rossiter-McLaughlin effect with an unusually large amplitude of several hundred m/s. We find that the orbit normal of the planet is likely to be well-aligned with the stellar spin axis, with a projected spin-orbit alignment of {lambda}=9.7{deg}+/-5.2{deg}. This is currently the second most rapidly rotating star to have a reflex signal (and thus mass determination) due to a planetary companion measured.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A111
- Title:
- Radial velocity of HD 85390, 90156 and 103197
- Short Name:
- J/A+A/526/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of three new extrasolar planets orbiting the solar type stars HD 85390, HD 90156 and HD 103197 with the HARPS spectrograph mounted on the ESO 3.6-m telescope at La Silla observatory. HD 85390 has a planetary companion with a projected intermediate mass (42.0M_earth_) on a 788-day orbit (a=1.52AU) with an eccentricity of 0.41, for which there is no analogue in the solar system. A drift in the data indicates the presence of another companion on a long period orbit, which is however not covered by our measurements. HD 90156 is orbited by a warm Neptune analogue with a minimum mass of 17.98M_earth_ (1.05M_neptune_), a period of 49.8 days (a=0.25AU) and an eccentricity of 0.31. HD 103197 has an intermediate mass planet on a circular orbit (P=47.8d, Msini=31.2M_earth_). We discuss the formation of planets of intermediate mass (30-100M_earth_) which should be rare inside a few AU according to core accretion formation models.
- ID:
- ivo://CDS.VizieR/J/A+A/457/1033
- Title:
- Radial velocity of HR 7224
- Short Name:
- J/A+A/457/1033
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HR 7224 is a rapidly rotating He-weak silicon star known as photometrically variable with a period of 1.123d. Drastic changes of photometric amplitude and period were reported in 2003. We investigate the star spectroscopically to determine the time scales of variability, to derive basic atmospheric parameters, and to give first estimates on possible surface structures. We investigate time series of more then 570 high-resolution spectra of HR 7224 for radial velocity and line profile variations. The rotation period is determined from period analysis of data. Comparing radial velocity and line profile variations we draw first conclusions on possible surface structures in terms of line strengths. From Balmer and metal lines we determine Teff, log(g), vsini and metal abundances depending on rotation phase. The star shows a remarkable half-amplitude of radial velocity variation of 6km/s. From this variation we deduce a rotation period of 1.12324d. The period and the double-wave shaped radial velocity curve are in agreement with earlier photometric findings. The observed radial velocity variations can be explained by the rotation period and its harmonics and no further periodic contributions were found in the residuals. HR 7224 has enhanced Si and Fe abundances whereas He is extremely depleted. The star shows line strength variations of all observed elements with the rotation period. Variations of radial velocity, line strength and line shape of silicon lines and their relationships can be explained by assuming two large spots on the stellar surface showing enhanced line strength. From Balmer lines we deduce different temperatures of the star for different rotation phases. The observed difference in amplitudes of the variation of Mg II and Si II lines supports the assumption of surface regions of different temperature on this presumably magnetic CP star. Synthetic uvby colors computed from adapted synthetic spectra confirm the high photometric amplitude reported for the 2003 light curves.
