- ID:
- ivo://CDS.VizieR/J/AJ/154/237
- Title:
- HARPS-N radial velocities of WASP-47
- Short Name:
- J/AJ/154/237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present precise radial velocity observations of WASP-47, a star known to host a hot Jupiter, a distant Jovian companion, and, uniquely, two additional transiting planets in short-period orbits: a super-Earth in a ~19 hr orbit, and a Neptune in a ~9 day orbit. We analyze our observations from the HARPS-N spectrograph along with previously published data to measure the most precise planet masses yet for this system. When combined with new stellar parameters and reanalyzed transit photometry, our mass measurements place strong constraints on the compositions of the two small planets. We find that, unlike most other ultra-short-period planets, the inner planet, WASP-47 e, has a mass (6.83+/-0.66 M_{Earth}_) and a radius (1.810+/-0.027 R_{Earth}_) that are inconsistent with an Earth-like composition. Instead, WASP-47 e likely has a volatile-rich envelope surrounding an Earth-like core and mantle. We also perform a dynamical analysis to constrain the orbital inclination of WASP-47 c, the outer Jovian planet. This planet likely orbits close to the plane of the inner three planets, suggesting a quiet dynamical history for the system. Our dynamical constraints also imply that WASP-47 c is much more likely to transit than a geometric calculation would suggest. We calculate a transit probability for WASP-47 c of about 10%, more than an order of magnitude larger than the geometric transit probability of 0.6%.
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- ID:
- ivo://CDS.VizieR/J/AJ/155/203
- Title:
- HARPS-N RVs & activity indicators for Kepler-1655
- Short Name:
- J/AJ/155/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the confirmation of a small, moderately irradiated (F=155+/-7 F_{Earth}_) Neptune with a substantial gas envelope in a P=11.8728787+/-0.0000085 day orbit about a quiet, Sun-like G0V star Kepler-1655. Based on our analysis of the Kepler light curve, we determined Kepler-1655b's radius to be 2.213+/-0.082 R_{Earth}_. We acquired 95 high-resolution spectra with Telescopio Nazionale Galileo/HARPS-N, enabling us to characterize the host star and determine an accurate mass for Kepler-1655b of 5.0_-2.8_^+3.1^ M_{Earth}_ via Gaussian-process regression. Our mass determination excludes an Earth-like composition with 98% confidence. Kepler-1655b falls on the upper edge of the evaporation valley, in the relatively sparsely occupied transition region between rocky and gas-rich planets. It is therefore part of a population of planets that we should actively seek to characterize further.
- ID:
- ivo://CDS.VizieR/J/A+A/489/1255
- Title:
- HARPS observations of eight galactic Cepheids
- Short Name:
- J/A+A/489/1255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We show that residual {gamma}-velocities (compared to a axisymmetric rotation model of the milky Way) are an intrinsic property of Cepheids. We observed eight galactic Cepheids with the HARPS spectroscope, focusing specifically on 17 spectral lines. For each spectral line of each star, we computed the {gamma}-velocity (resp. {gamma}-asymmetry) as an average value of the interpolated radial velocity (resp. line asymmetry) curve. For each Cepheid in our sample, a linear relation is found between the {gamma}-velocities of the various spectral lines and their corresponding {gamma}-asymmetries, showing that residual {gamma}-velocities stem from the intrinsic properties of Cepheids. We also provide a physical reference to the stellar {gamma}-velocity: it should be zero when the {gamma}-asymmetry is zero. Following this definition, we provide very precise and physically calibrated estimates of the {gamma}-velocities for all stars of our sample.
- ID:
- ivo://CDS.VizieR/J/A+A/453/309
- Title:
- HARPS observations of nine galactic Cepheids
- Short Name:
- J/A+A/453/309
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The ratio of pulsation to radial velocity (the projection factor) is currently limiting the accuracy of the Baade-Wesselink method, and in particular of its interferometric version recently applied to several nearby Cepheids. This work aims at establishing a link between the line asymmetry evolution over the Cepheids' pulsation cycles and their projection factor, with the final objective to improve the accuracy of the Baade-Wesselink method for distance determinations. We present HARPS high spectral resolution observations (R=120000) of nine galactic Cepheids: R Tra, S Cru, Y Sgr, beta Dor, zeta Gem, Y Oph, RZ Vel, l Car and RS Pup, having a good period sampling (P=3.39d to P=41.52d). We fit spectral line profiles by an asymmetric bi-Gaussian to derive radial velocity, Full-Width at Half-Maximum in the line (FWHM) and line asymmetry for all stars.
- ID:
- ivo://CDS.VizieR/J/A+A/502/951
- Title:
- HARPS observations of nine galactic Cepheids
- Short Name:
- J/A+A/502/951
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed eight galactic Cepheids with the HARPS spectrograph. For each star, we derive an interpolated cross-correlated radial velocity curve using the HARPS pipeline. Pulsating phases and HARPS radial velocity measurements can be found in Table 1. The cross correlation method is widely used to derive the radial velocity curve of Cepheids when the signal to noise ratio of the spectra is low. However, if it is used with an inac curate projection factor, it might introduce some biases in the Baade-Wesselink (BW) methods of determining the distance of Cepheids. In addition, it might affect the average value of the radial velocity curve (or gamma-velocity) important for Galactic structure studies. See the paper for details and results.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A28
- Title:
- HARPSpol magnetic massive stars
- Short Name:
- J/A+A/567/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph.
- ID:
- ivo://CDS.VizieR/J/ApJ/876/L24
- Title:
- HARPS radial velocities of the host star HD15337
- Short Name:
- J/ApJ/876/L24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V=9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary nature of the transit signals and derive the masses of the two transiting planets. With an orbital period of 4.8d, a mass of 7.51_-1.01^+1.09^M{Earth}_ and a radius of 1.64+/-0.06R_{Earth}_, HD15337b joins the growing group of short-period super-Earths known to have a rocky terrestrial composition. The sub-Neptune HD15337c has an orbital period of 17.2d, a mass of 8.11_-1.69_^+1.82^M_{Earth}_, and a radius of 2.39+/-0.12R_{Earth}_, suggesting that the planet might be surrounded by a thick atmospheric envelope. The two planets have similar masses and lie on opposite sides of the radius gap, and are thus an excellent testbed for planet formation and evolution theories. Assuming that HD15337c hosts a hydrogen-dominated envelope, we employ a recently developed planet atmospheric evolution algorithm in a Bayesian framework to estimate the history of the high-energy (extreme ultraviolet and X-ray) emission of the host star. We find that at an age of 150Myr, the star possessed on average between 3.7 and 127 times the high-energy luminosity of the current Sun.
- ID:
- ivo://CDS.VizieR/J/AJ/162/174
- Title:
- HARPS radial velocity follow up of GJ 1214
- Short Name:
- J/AJ/162/174
- Date:
- 21 Mar 2022 00:16:00
- Publisher:
- CDS
- Description:
- We present an intensive effort to refine the mass and orbit of the enveloped terrestrial planet GJ1214b using 165 radial velocity (RV) measurements taken with the HARPS spectrograph over a period of 10years. We conduct a joint analysis of the RVs with archival Spitzer/IRAC transits and measure a planetary mass and radius of 8.17{+/-}0.43M{Earth} and 2.742-_0.053_^+0.050^R{Earth}. Assuming that GJ1214b is an Earth-like core surrounded by a H/He envelope, we measure an envelope mass fraction of X_env_=5.24_-0.29_^+0.30^%. GJ1214b remains a prime target for secondary eclipse observations of an enveloped terrestrial, the scheduling of which benefits from our constraint on the orbital eccentricity of <0.063 at 95% confidence, which narrows the secondary eclipse window to 2.8hr. By combining GJ1214 with other mid-M-dwarf transiting systems with intensive RV follow up, we calculate the frequency of mid-M-dwarf planetary systems with multiple small planets and find that 90_-21_^+5^% of mid-M dwarfs with a known planet with mass [1,10]M{Earth} and orbital period [0.5,50]days, will host at least one additional planet. We rule out additional planets around GJ1214 down to 3M{Earth} within 10days, such that GJ1214 is a single-planet system within these limits. This result has a 44_-5_^+9^ probability given the prevalence of multiplanet systems around mid-M dwarfs. We also investigate mid-M-dwarf RV systems and show that the probability that all reported RV planet candidates are real planets is <12% at 99% confidence, although this statistical argument is unable to identify the probable false positives.
- ID:
- ivo://CDS.VizieR/J/AJ/162/79
- Title:
- HARPS radial velocity follow up of TOI-1634
- Short Name:
- J/AJ/162/79
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Studies of close-in planets orbiting M dwarfs have suggested that the M-dwarf radius valley may be well explained by distinct formation timescales between enveloped terrestrials and rocky planets that form at late times in a gas-depleted environment. This scenario is at odds with the picture that close-in rocky planets form with a primordial gaseous envelope that is subsequently stripped away by some thermally driven mass-loss process. These two physical scenarios make unique predictions of the rocky/enveloped transition's dependence on orbital separation such that studying the compositions of planets within the M-dwarf radius valley may be able to establish the dominant physics. Here, we present the discovery of one such keystone planet: the ultra-short-period planet TOI-1634b (P=0.989days, F=121F{Earth}, r_p_=1.790_-0.081_^+0.080^R{Earth}) orbiting a nearby M2 dwarf (K_s_=8.7, R_s_=0.450R{sun}, M_s_=0.502M{sun}) and whose size and orbital period sit within the M-dwarf radius valley. We confirm the TESS-discovered planet candidate using extensive ground-based follow-up campaigns, including a set of 32 precise radial velocity measurements from HARPS-N. We measure a planetary mass of 4.91_-0.70_^+0.68^M{Earth}, which makes TOI-1634b inconsistent with an Earth-like composition at 5.9{sigma} and thus requires either an extended gaseous envelope, a large volatile-rich layer, or a rocky composition that is not dominated by iron and silicates to explain its mass and radius. The discovery that the bulk composition of TOI-1634b is inconsistent with that of Earth supports the gas-depleted formation mechanism to explain the emergence of the radius valley around M dwarfs with M_s_<~0.5M{sun}.
- ID:
- ivo://CDS.VizieR/J/ApJS/200/15
- Title:
- HARPS-TERRA project. I.
- Short Name:
- J/ApJS/200/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Doppler spectroscopy has uncovered or confirmed all the known planets orbiting nearby stars. Two main techniques are used to obtain precision Doppler measurements at optical wavelengths. The first approach is the gas cell method, which consists of least-squares matching of the spectrum of iodine imprinted on the spectrum of the star. The second method relies on the construction of a stabilized spectrograph externally calibrated in wavelength. The most precise stabilized spectrometer in operation is the High Accuracy Radial velocity Planet Searcher (HARPS), operated by the European Southern Observatory in La Silla Observatory, Chile. The Doppler measurements obtained with HARPS are typically obtained using the cross-correlation function (CCF) technique. This technique consists of multiplying the stellar spectrum by a weighted binary mask and finding the minimum of the product as a function of the Doppler shift. It is known that CCF is suboptimal in exploiting the Doppler information in the stellar spectrum. Here we describe an algorithm to obtain precision radial velocity measurements using least-squares matching of each observed spectrum to a high signal-to-noise ratio template derived from the same observations. This algorithm is implemented in our software HARPS-TERRA (Template-Enhanced Radial velocity Re-analysis Application). New radial velocity measurements on a representative sample of stars observed by HARPS are used to illustrate the benefits of the proposed method. We show that, compared with CCF, template matching provides a significant improvement in accuracy, especially when applied to M dwarfs.
