- ID:
- ivo://CDS.VizieR/J/AJ/157/33
- Title:
- Radial velocity exploration of {epsilon} Eridani
- Short Name:
- J/AJ/157/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most sensitive direct imaging and radial velocity (RV) exploration of {epsilon} Eridani to date. {epsilon} Eridani is an adolescent planetary system, reminiscent of the early solar system. It is surrounded by a prominent and complex debris disk that is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 yr ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 yr, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7 {mu}m) with the vortex coronagraph recently installed in W.M. Keck Observatory's infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. {epsilon} Eridani b has a mass of 0.78_-0.12_^+0.38^ M_Jup_ and is orbiting {epsilon} Eridani at about 3.48+/-0.02 au with a period of 7.37+/-0.07 yr. The eccentricity of {epsilon} Eridani b's orbit is 0.07_-0.05_^+0.06^, an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet-disk interactions and prospects for future detection and characterization with the James Webb Space Telescope.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/593/A5
- Title:
- Radial velocity fitting challenge dataset
- Short Name:
- J/A+A/593/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar signals are the main limitation for precise radial-velocity (RV) measurements. These signals arise from the photosphere of the stars. The m/s perturbation created by these signals prevents the detection and mass characterization of small-mass planetary candidates such as Earth-twins. Several methods have been proposed to mitigate stellar signals in RV measurements. However, without precisely knowing the stellar and planetary signals in real observations, it is extremely difficult to test the efficiency of these methods. The goal of the RV fitting challenge is to generate simulated RV data including stellar and planetary signals and to perform a blind test within the community to test the efficiency of the different methods proposed to recover planetary signals despite stellar signals. In this first paper, we describe the simulation used to model the measurements of the RV fitting challenge. Each simulated planetary system includes the signals from instrumental noise, stellar oscillations, granulation, supergranulation, stellar activity, and observed and simulated planetary systems. In addition to RV variations, this simulation also models the effects of instrumental noise and stellar signals on activity observables obtained by HARPS-type high-resolution spectrographs, that is, the calcium activity index log(R'HK),and the bisector span and full width at half maximum of the cross-correlation function. We publish the 15 systems used for the RV fitting challenge including the details about the planetary systems that were injected into each of them.
- ID:
- ivo://CDS.VizieR/J/AJ/162/61
- Title:
- Radial velocity follow up of Barnard's star with HPF
- Short Name:
- J/AJ/162/61
- Date:
- 14 Mar 2022 07:00:45
- Publisher:
- CDS
- Description:
- Barnard's star is among the most studied stars given its proximity to the Sun. It is often considered the radial velocity (RV) standard for fully convective stars due to its RV stability and equatorial decl. Recently, an M_sini_=3.3M{Earth} super-Earth planet candidate with a 233day orbital period was announced by Ribas et al. New observations from the near-infrared Habitable-zone Planet Finder (HPF) Doppler spectrometer do not show this planetary signal. We ran a suite of experiments on both the original data and a combined original + HPF data set. These experiments include model comparisons, periodogram analyses, and sampling sensitivity, all of which show the signal at the proposed period of 233days is transitory in nature. The power in the signal is largely contained within 211 RVs that were taken within a 1000 day span of observing. Our preferred model of the system is one that features stellar activity without a planet. We propose that the candidate planetary signal is an alias of the 145day rotation period. This result highlights the challenge of analyzing long-term, quasi-periodic activity signals over multiyear and multi-instrument observing campaigns.
- ID:
- ivo://CDS.VizieR/J/AJ/154/123
- Title:
- Radial velocity follow-up of the HD 3167 system
- Short Name:
- J/AJ/154/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 3167 is a bright (V=8.9 mag) K0 V star observed by NASA's K2 space mission during its Campaign 8. It has recently been found to host two small transiting planets, namely, HD 3167b, an ultra-short-period (0.96 days) super-Earth, and HD 3167c, a mini-Neptune on a relatively long-period orbit (29.85 days). Here we present an intensive radial velocity (RV) follow-up of HD 3167 performed with the FIES@NOT, HARPS@ESO-3.6 m, and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69+/-0.44 M_{Earth}_, a radius of 1.574+/-0.054 R_{Earth}_, and a mean density of 8.00_-0.98_^+1.10^ g/cm^3^, HD 3167b joins the small group of ultra-short-period planets known to have rocky terrestrial compositions. HD 3167c has a mass of 8.33_-1.85_^+1.79^ M_{Earth}_ and a radius of 2.740_-0.100_^+0.106^ R_{Earth}_, yielding a mean density of 2.21_-0.53_^+0.56^ g/cm^3^, indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (~350 km) and the brightness of the host star make HD 3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the RV measurements but the currently available data set does not allow us to draw any firm conclusions on the origin of the observed variation.
- ID:
- ivo://CDS.VizieR/J/AJ/162/238
- Title:
- Radial velocity follow up of Wolf 503
- Short Name:
- J/AJ/162/238
- Date:
- 11 Mar 2022 06:30:07
- Publisher:
- CDS
- Description:
- Using radial-velocity measurements from four instruments, we report the mass and density of a 2.043{+/-}0.069R{Earth} sub-Neptune orbiting the quiet K-dwarf Wolf503 (HIP67285). In addition, we present improved orbital and transit parameters by analyzing previously unused short-cadence K2 campaign 17 photometry and conduct a joint radial-velocity-transit fit to constrain the eccentricity at 0.41{+/-}0.05. The addition of a transit observation by Spitzer also allows us to refine the orbital ephemeris in anticipation of further follow-up. Our mass determination, 6.26_-0.70_^+0.69^M{Earth} , in combination with the updated radius measurements, gives Wolf503b a bulk density of {rho}=2.92_-0.44_^+0.50^g/cm^3^. Using interior composition models, we find this density is consistent with an Earth-like core with either a substantial H_2_O mass fraction (45_-16_^+19^%) or a modest H/He envelope (0.5%{+/-}0.3%). The low H/He mass fraction, along with the old age of Wolf503 (11{+/-}2Gyr), makes this sub-Neptune an opportune subject for testing theories of XUV-driven mass loss while the brightness of its host (J=8.3mag) makes it an attractive target for transmission spectroscopy.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A142
- Title:
- Radial velocity for GJ 1132
- Short Name:
- J/A+A/618/A142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The source GJ1132 is a nearby red dwarf known to host a transiting Earth-size planet. After its initial detection, we pursued an intense follow-up with the HARPS velocimeter. We now confirm the detection of GJ1132b with radial velocities alone. We refined its orbital parameters, and in particular, its mass (m_b_= 1.66+/-0.23M_{sun}_), density ({rho}_b_=6.3+/-1.3g/cm^3^), and eccentricity (e_b_<0.22; 95%). We also detected at least one more planet in the system. GJ1132c is a super-Earth with period P_c_=8.93+/-0.01-days and minimum mass m_c_sini_c_=2.64+/-0.44M_{sun}_. Receiving about 1.9 times more flux than Earth in our solar system, its equilibrium temperature is that of a temperate planet (T_eq_=230-300K for albedos A=0.75-0.00), which places GJ1132c near the inner edge of the so-called habitable zone. Despite an a priori favorable orientation for the system, Spitzer observations reject most transit configurations, leaving a posterior probability <1% that GJ11 32c transits. GJ1132(d) is a third signal with period P_d_=177+/-5-days attributed to either a planet candidate with minimum mass m_d_sini_d_=8.4^+1.7^_-2.5_M_{sun}_ or stellar activity. Its Doppler signal is the most powerful in our HARPS time series but appears on a timescale where either the stellar rotation or a magnetic cycle are viable alternatives to the planet hypothesis. On the one hand, the period is different than that measured for the stellar rotation (~125-days), and a Bayesian statistical analysis we performed with a Markov chain Monte Carlo and Gaussian processes demonstrates that the signal is better described by a Keplerian function than by correlated noise. On the other hand, periodograms of spectral indices sensitive to stellar activity show power excess at similar periods to that of this third signal, and radial velocity shifts induced by stellar activity can also match a Keplerian function. We therefore prefer to leave the status of GJ1132(d) undecided.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A25
- Title:
- Radial velocity for Ross 128
- Short Name:
- J/A+A/613/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After that a new technique combining high-contrast imaging and high-dispersion spectroscopy successfully detected the atmosphere of a giant planet, it soon became contemplated as one of the most promising avenues to study the atmosphere of Earth-size worlds. With the forthcoming ELTs, it shall gain the angular resolution and sensitivity to even detect O2 in the atmosphere of planets orbiting red dwarfs. This is a strong motivation to make the census of planets around cool stars which habitable zones can be resolved by ELTs, i.e. for M dwarfs within ~5-parsecs. In that context, our HARPS survey is already a major contributor to that sample of nearby planets. Here we report on our radial-velocity observations of Ross 128 (Proxima Virginis, GJ447, HIP 57548), a M4 dwarf just 3.4-parsec away from our Sun. We detect it is host of an exo-Earth with a projected mass m*sini=1.35M_{sun}_ and an orbital period of 9.9-days. Ross 128 b receives ~1.38 as much flux as Earth from the Sun and has an equilibrium temperature between 269K (resp. 213K) for an Earth-like (resp. Venus-like) albedo. According to recent studies, it is located at the inner edge of the so called habitable zone. An 80-day long light curve performed by K2 during campaign C01 excludes Ross 128 b is a transiting planet. Together with ASAS photometry and other activity indices, it argues for a long rotational period and a weak activity which, in the context of habitability, gives a high merit to the detection. Today, Ross 128 b is the second closest known exo-Earth after Proxima Centauri b (1.3 parsec) and the closest known temperate planet around a quiet star. At maximum elongation, the planet-star angular separation of 15 milli-arcsec will be resolved by the ELT (>3{lambda}/D) in all optical bands of O_2_.
- ID:
- ivo://CDS.VizieR/J/AJ/162/117
- Title:
- Radial velocity for 19 RR Lyrae
- Short Name:
- J/AJ/162/117
- Date:
- 21 Mar 2022 00:54:18
- Publisher:
- CDS
- Description:
- We report 272 radial velocities for 19 RR-Lyrae variables. For most of the stars we have radial velocities for the complete pulsation cycle. These data are used to determine robust center-of-mass radial velocities that have been compared to values from the literature in a search for evidence of binary systems. Center-of-mass velocities were determined for each star using Fourier Series and template fits to the radial velocities. Our center-of-mass velocities have uncertainties from {+/-}0.16km/s to {+/-}2.5km/s, with a mean uncertainty of {+/-}0.92km/s. We combined our center-of-mass velocities with values from the literature to look for deviations from the mean center-of-mass velocity of each star. Fifteen RR-Lyrae show no evidence of binary motion (BK And, CI And, Z CVn, DM Cyg, BK Dra, RR Gem, XX Hya, SZ Leo, BX Leo, TT Lyn, CN Lyr, TU Per, U Tri, RV UMa, and AV Vir). In most cases this conclusion is reached due to the sporadic sampling of the center-of-mass velocities over time. Three RR Lyrae show suspicious variation in the center-of-mass velocities that may indicate binary motion but do not prove it (SS Leo, ST Leo, and AO Peg). TU UMa was observed by us near a predicted periastron passage (at 0.14 in orbital phase) but the absence of additional center-of-mass velocities near periastron makes the binary detection, based on radial velocities alone, uncertain. Two stars in our sample show H{gamma} emission in phases 0.9-1.0: SS Leo and TU UMa.
- ID:
- ivo://CDS.VizieR/J/A+A/551/A73
- Title:
- Radial Velocity for WASP-54b, WASP-56b and WASP-57b
- Short Name:
- J/A+A/551/A73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet, and orbits a F9 star, evolving off the main sequence, every 3.69 days. WASP-56b and WASP-57b orbit main sequence stars of spectral type G6 every 4.67 and 2.84 days, respectively. WASP-56b and WASP-57b show no radius anomaly and a high density implying a large core of heavy elements; possibly as high as 50M_Earth_ in the case of WASP-57b. We present the Radial Velocity and line bisector span measurements for the transiting planet host stars WASP-54, WASP-56 and WASP-57.
1570. Radial velocity in Draco
- ID:
- ivo://CDS.VizieR/J/MNRAS/330/792
- Title:
- Radial velocity in Draco
- Short Name:
- J/MNRAS/330/792
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present stellar radial velocity data for the Draco dwarf spheroidal (dSph) galaxy obtained using the AF2/WYFFOS instrument combination on the William Herschel Telescope. Our data set consists of 186 member stars, 159 of which have good quality velocities, extending to a magnitude V~19.5 with a mean velocity precision of ~2km/s. As this survey is based on a high-precision photometric target list, it contains many more Draco members at large radii. For the first time, this allows a robust determination of the radial behaviour of the velocity dispersion in a dSph.
