- ID:
- ivo://CDS.VizieR/J/A+A/636/A74
- Title:
- HARPS radial velocity database
- Short Name:
- J/A+A/636/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph is mounted since 2003 at the ESO 3.6m telescope in La Silla and provides state-of-the-art stellar radial velocity (RV) measurements with a precision down to ~1m/s. The spectra are extracted with a dedicated data-reduction software (DRS) and the RVs are computed by cross correlating with a numerical mask. The aim of this study is three-fold: (i) Create an easy access to the public HARPS RV data set. (ii) Apply the new public SpEctrum Radial Velocity AnaLyser (SERVAL) pipeline to the spectra, and produce a more precise RV data set. (iii) Check whether the precision of the RVs can be further improved by correcting for small nightly systematic effects. For each star observed with HARPS, we downloaded the publicly available spectra from the ESO archive, and recomputed the RVs with SERVAL. This was based on fitting each observed spectrum with a high signal-to-noise ratio template created by co-adding all the available spectra of that star. We then computed nightly zero points (NZPs) by averaging the RVs of quiet stars. Analysing the RVs of the most RV-quiet stars, whose RV scatter is <5m/s, we find that SERVAL RVs are on average more precise than DRS RVs by a few percent. Investigating the NZP time series, we find three significant systematic effects, whose magnitude is independent of the software used for the RV derivation: (i) stochastic variations with a magnitude of ~1m/s; (ii) longterm variations, with a magnitude of ~1m/s and a typical timescale of a few weeks; and (iii) 20-30NZPs significantly deviating by few m/s. In addition, we find small (<~1m/s) but significant intra-night drifts in DRS RVs before the 2015 intervention, and in SERVAL RVs after it. We confirm that the fibre exchange in 2015 caused a discontinuous RV jump, which strongly depends on the spectral type of the observed star: from ~14m/s for late F-type stars, to ~-3m/sx for M dwarfs. The combined effect of extracting the RVs with SERVAL and correcting them for the systematics we find is an improved average RV precision: ~5% improvement for spectra taken before the 2015 intervention, and ~15% improvement for spectra taken after it. To demonstrate the quality of the new RV data set, we present an updated orbital solution of the GJ 253 two-planet system. Our NZP-corrected SERVAL RVs can be retrieved from a user-friendly, public database. It provides more than 212000 RVs for about 3000 stars along with many auxiliary information, such as the NZP corrections, various activity indices, and DRS-CCF products.
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Search Results
- 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/A+A/575/A119
- Title:
- HARPS RV and stellar activity
- Short Name:
- J/A+A/575/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planetary companions of a fixed mass induce reflex motions with a larger amplitude around lower-mass stars, which adds to making M dwarfs excellent targets for extra-solar planet searches. The most recent velocimeters with a stability of can detect very low-mass planets out to the habitable zone of these stars. Low-mass small planets are abundant around M dwarfs, and most of the known potentially habitable planets orbit one of these cool stars. Our M-dwarf radial velocity monitoring with HARPS on the ESO 3.6m telescope at La Silla observatory makes a major contribution to this sample. We present here dense radial velocity (RV) time series for three M dwarfs observed over ~five years: GJ 3293 (0.42M_{sun}_), GJ 3341 (0.47M_{sun}_), and GJ 3543 (0.45M_{sun}_). We extracted these RVs through minimum chi^2^ -matching of each spectrum against a stack of all observed spectra for the same star that has a high S/N ratio. We then compared potential orbital signals against several stellar activity indicators to distinguish the Keplerian variations induced by planets from the spurious signals that result from rotational modulation of stellar surface inhomogeneities and from activity cycles.
- ID:
- ivo://CDS.VizieR/J/A+A/512/A48
- Title:
- HARPS RV curves of HD125612, HD215497, HIP5158
- Short Name:
- J/A+A/512/A48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detections of three multiple systems within the HARPS volume-limited sample. Among the six planets discussed in this paper we have identified a "super-Earth" planet with a minimum mass of 6.6M_{Earth}_ and a "Neptune" planet with minimum mass of 18M_{Earth}_, both orbiting their parent stars within a distance of 0.05AU and a period of approximately four days. These detections strengthen the argument that low-mass planets are primarily found in multiple-planetary systems.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/110
- Title:
- HARPS timeseries data for HD41248
- Short Name:
- J/ApJ/794/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaining a better understanding of the effects of stellar-induced radial velocity noise is critical for the future of exoplanet studies since the discovery of the lowest-mass planets using this method will require us to go below the intrinsic stellar noise limit. An interesting test case in this respect is that of the southern solar analog HD 41248. The radial velocity time series of this star has been proposed to contain either a pair of signals with periods of around 18 and 25 days, which could be due to a pair of resonant super-Earths, or a single and varying 25 day signal that could arise due to a complex interplay between differential rotation and modulated activity. In this work, we build up more evidence for the former scenario, showing that the signals are still clearly significant, even after more than 10 yr of observations, and they likely do not change in period, amplitude, or phase as a function of time, the hallmarks of static Doppler signals. We show that over the last two observing seasons, this star was more intrinsically active and the noise reddened, highlighting why better noise models are needed to find the lowest amplitude signals, in particular, models that consider noise correlations. This analysis shows that there is still sufficient evidence for the existence of two super-Earths on the edge of, or locked into, a 7:5 mean motion resonance orbiting HD 41248.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A104
- Title:
- HARPS XLVI. RV data for the 5 targets
- Short Name:
- J/A+A/654/A104
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present precise radial-velocity measurements of five solar-type stars observed with the HARPS Echelle spectrograph mounted on the 3.6-m telescope in La Silla (ESO, Chile). With a time span of more than 10 years and a fairly dense sampling, the survey is sensitive to low mass planets down to super-Earths on orbital periods up to 100 days. Our goal was to search for planetary companions around the stars HD39194, HD93385, HD96700, HD154088, and HD189567 and use Bayesian model comparison to make an informed choice on the number of planets present in the systems based on the radial velocity observations. These findings will contribute to the pool of known exoplanets and better constrain their orbital parameters. A first analysis was performed using the DACE (Data & Analysis Center for Exoplanets) online tools to assess the activity level of the star and the potential planetary content of each system. We then used Bayesian model comparison on all targets to get a robust estimate of the number of planets per star. We did this using the nested sampling algorithm PolyChord. For some targets, we also compared different noise models to disentangle planetary signatures from stellar activity. Lastly, we ran an efficient MCMC (Markov chain Monte Carlo) algorithm for each target to get reliable estimates for the planets' orbital parameters. We identify 12 planets within several multiplanet systems. These planets are all in the super-Earth and sub-Neptune mass regime with minimum masses ranging between 4 and 13 M_{Earth}_ and orbital periods between 5 and 103 days. Three of these planets are new, namely HD 93385 b, HD 96700 c, and HD 189567 c.
- ID:
- ivo://CDS.VizieR/J/A+A/523/A15
- Title:
- HARPS XXIII: RV data for the 8 targets
- Short Name:
- J/A+A/523/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present our HARPS radial-velocity data for eight low-activity solar-type stars belonging to the HARPS volume-limited sample: HD6718, HD8535, HD28254, HD290327, HD43197, HD44219, HD148156, and HD156411. Keplerian fits to these data reveal the presence of low-mass companions around these targets. With minimum masses ranging from 0.58 to 2.54M_{Jup}_, these companions are in the planetary mass domain. The orbital periods of these planets range from slightly less than one to almost seven years. The eight orbits presented in this paper exhibit a wide variety of eccentricities: from 0.08 to above 0.8.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A44
- Title:
- HARPS Young Nearby Stars - YNS
- Short Name:
- J/A+A/633/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young nearby stars are good candidates in the search for planets with both radial velocity (RV) and direct imaging techniques. This, in turn, allows for the computation of the giant planet occurrence rates at all separations. The RV search around young stars is a challenge as they are generally faster rotators than older stars of similar spectral types and they exhibit signatures of magnetic activity (spots) or pulsation in their RV time series. Specific analyses are necessary to characterize, and possibly correct for, this activity. Our aim is to search for planets around young nearby stars and to estimate the giant planet (GP) occurrence rates for periods up to 1000 days. We used the HARPS spectrograph on the 3.6m telescope at La Silla Observatory to observe 89 A-M young (<600Myr) stars. We used our SAFIR (Spectroscopic data via Analysis of the Fourier Interspectrum Radial velocities) software to compute the RV and other spectroscopic observables. Then, we computed the companion occurrence rates on this sample. We confirm the binary nature of HD 177171, HD 181321 and HD 186704. We report the detection of a close low mass stellar companion for HIP 36985. No planetary companion was detected. We obtain upper limits on the GP (<13M_Jup_) and BD ({in}[13;80]M_Jup_) occurrence rates based on 83 young stars for periods less than 1000 days, which are set, 2_-2_^+3^ and 1_-1_^+3^%.
