- ID:
- ivo://CDS.VizieR/J/A+A/612/A41
- Title:
- HD 176986 HARPS + HARPS-N data
- Short Name:
- J/A+A/612/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a system of two super-Earths orbiting the moderately active K-dwarf HD 176986. This work is part of the RoPES RV program of G- and K-type stars that combines radial velocity from both HARPS and HARPS-N spectrograph to search for short-period terrestrial planets. HD 176986 b and c are super-Earth mass planets with masses of 5.74 and 9.18 Me, with orbital periods of 6.49 and 16.82 days, at a distances of 0.063 and 0.119AU, in orbits that are consistent with circular. The host star is a K2.5 dwarf, and in spite of its modest level of chromospheric activity log(R'hk)=-4.90+/-0.04, shows a complex activity pattern. Along with the discovery of the planets we study the magnetic cycle and rotation of the star. HD 176986 proves to be suitable to test the available techniques of RV analysis and our understanding of stellar activity.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/503/1248
- Title:
- HD 13808 HARPS radial velocities
- Short Name:
- J/MNRAS/503/1248
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive analysis of 10 years of HARPS radial velocities of the K2V dwarf star HD13808, which has previously been reported to host two unconfirmed planet candidates. We use the state-of-the-art nested sampling algorithm PolyChord to compare a wide variety of stellar activity models, including simple models exploiting linear correlations between RVs and stellar activity indicators, harmonic models for the activity signals, and a more sophisticated Gaussian process regression model. We show that the use of overly-simplistic stellar activity models that are not well-motivated physically can lead to spurious `detections' of planetary signals that are almost certainly not real. We also reveal some difficulties inherent in parameter and model inference in cases where multiple planetary signals may be present. Our study thus underlines the importance both of exploring a variety of competing models and of understanding the limitations and precision settings of one's sampling algorithm. We also show that at least in the case of HD 13808, we always arrive at consistent conclusions about two particular signals present in the RV, regardless of the stellar activity model we adopt; these two signals correspond to the previously-reported though unconfirmed planet candidate signals. Given the robustness and precision with which we can characterize these two signals, we deem them secure planet detections. In particular, we find two planets orbiting HD13808 at distances of 0.11, 0.26AU with periods of 14.2, 53.8d, and minimum masses of 11, 10 Earth masses.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A103
- Title:
- HD20794 HARPS radial velocities
- Short Name:
- J/A+A/605/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the feasibility of detecting Earth analogs around Sun-like stars using the radial velocity method by investigating one of the largest radial velocities datasets for the one of the most stable radial-velocity stars HD20794. We proceed by disentangling the Keplerian signals from correlated noise and activity-induced variability. We diagnose the noise using the differences between radial velocities measured at different wavelength ranges, so-called "differential radial velocities", as well as the combination of radial velocities measured for other stars to account for instrumental effects. We apply this method to the radial velocities measured by HARPS, and identify four signals at 18, 89, 147 and 330d. The two signals at periods of 18 and 89d are previously reported and are better quantified in this work. The signal at a period of about 147d is reported for the first time, and corresponds to a super-Earth with a minimum mass of 4.59 Earth mass located 0.51AU from HD20794. We also find a significant signal at a period of about 330d corresponding to a super-Earth or Neptune in the habitable zone. Since this signal is close to the annual sampling period and significant periodogram power in some noise proxies are found close to this signal, further observations and analyses are required to confirm it. The analyses of the eccentricity and consistency of signals provide weak evidence for the existence of the previously reported 43d signal and a new signal at a period of about 11.9d with a semi amplitude of 0.4m/s. We find that the detection of a number of signals with radial velocity variations around 0.5m/s likely caused by low mass planet candidates demonstrates the important role of noise modeling in searching for Earth analogs.
- ID:
- ivo://CDS.VizieR/J/A+A/629/A75
- Title:
- HD 97048 H13CO+ and HC15N first detections
- Short Name:
- J/A+A/629/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of different molecular lines in protoplanetary disks provide valuable information on the gas kinematics, as well as constraints on the radial density and temperature structure of the gas. With ALMA we have detected H13CO+ (J=4-3) and HC15N (J=4-3) in the HD 97048 protoplanetary disk for the first time. We compare these new detections to the ringed continuum mm-dust emission and the spatially resolved CO (J=3-2) and HCO+ (J=4-3) emission. The radial distributions of the H^13^CO^+^ and HC^15^N emission show hints of ringed sub-structure whereas, the optically thick tracers, CO and HCO+, do not. We calculate the HCO^+^/H^13^CO^+^ intensity ratio across the disk and find that it is radially constant (within our uncertainties). We use a physio-chemical parametric disk structure of the HD 97048 disk with an analytical prescription for the HCO^+^ abundance distribution to generate synthetic observations of the HCO^+^ and H^13^CO^+^ disk emission assuming LTE. The best by-eye fit models require radial variations in the HCO^+^/H^13^CO^+^ abundance ratio and an overall enhancement in H^13^CO^+^ relative to HCO^+^. This highlights the need to consider isotope selective chemistry and in particular low temperature carbon isotope exchange reactions. This also points to the presence of a reservoir of cold molecular gas in the outer disk (T<10K, R>200au). Chemical models are required to confirm that isotope-selective chemistry alone can explain the observations presented here. With these data, we cannot rule out that the known dust substructure in the HD 97048 disk is responsible for the observed trends in molecular line emission, and higher spatial resolution observations are required to fully explore the potential of optically thin tracers to probe planet-carved dust gaps. We also report non-detections of H^13^CO^+^ and HC^15^N in the HD 100546 protoplanetary disk.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A9
- Title:
- HD17674, HD29021, and HD42012 radial velocities
- Short Name:
- J/A+A/601/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radial velocity measurements for three low-metallicity solar-like stars observed with the SOPHIE spectrograph and its predecessor ELODIE, both installed at the 193cm telescope of the Haute-Provence Observatory, allowing the detection and characterization of three new giant extrasolar planets in intermediate periods of 1.7 to 3.7yr. All three stars, HD 17674, HD 42012 and HD 29021 present single giant planetary companions with minimum masses between 0.9 and 2.5M_Jup_. The range of periods and masses of these companions, along with the distance of their host stars, make them good targets to look for astrometric signals over the lifetime of the new astrometry satellite Gaia. We discuss the preliminary astrometric solutions obtained from the first Gaia data release.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A134
- Title:
- HD1461, HD40307, and HD204313 radial velocities
- Short Name:
- J/A+A/585/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of the entire HARPS observations of three stars that host planetary systems: HD1461, HD40307, and HD204313. The data set spans eight years and contains more than 200 nightly averaged velocity measurements for each star. This means that it is sensitive to both long-period and low-mass planets and also to the e ects induced by stellar activity cycles. We modelled the data using Keplerian functions that correspond to planetary candidates and included the short- and long-term effects of magnetic activity. A Bayesian approach was taken both for the data modelling, which allowed us to include information from activity proxies such as log(R'_HK_) in the velocity modelling, and for the model selection, which permitted determining the number of significant signals in the system. The Bayesian model comparison overcomes the limitations inherent to the traditional periodogram analysis. We report an additional super-Earth planet in the HD1461 system. Four out of the six planets previously reported for HD40307 are confirmed and characterised. We discuss the remaining two proposed signals. In particular, we show that when the systematic uncertainty associated with the techniques for estimating model probabilities are taken into account, the current data are not conclusive concerning the existence of the habitable-zone candidate HD40307 g. We also fully characterise the Neptune-mass planet that orbits HD204313 in 34.9 days.
- ID:
- ivo://CDS.VizieR/IV/17A
- Title:
- HD,HDE,DM Identifications in Open Clusters
- Short Name:
- IV/17A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation of cross-identifications between the numbering system of Mermilliod (1978) for stars in open clusters and the numbering systems of several other astronomical catalogs, including HR, HD-HDE, DM, LS, LSS, GCVS, IDS, ADS, SAO, and several smaller lists. Also included are files listing the inverse cross-identifications from each catalog to the Mermilliod (1978) numbers. This version updates and expands the version presented by Mermilliod (1976A&AS...23..419M). The catalog is in 13 files: the first file contains the main cross- identification list from the Mermilliod (1978) system to the other catalogs; the next 11 files contain the inverse lists from the catalogs to Mermilliod (1978); and the thirteenth file contains a list of the references adopted for the individual star numberings for each cluster used by the Mermilliod (1978) system.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/227
- Title:
- HD 133029 & HD 192913 elemental abundances
- Short Name:
- J/A+AS/137/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fine analyses of the silicon stars HD 133029 and HD 192913 are presented using ATLAS9 model atmospheres whose predictions fit the optical region spectrophotometry and H{gamma} profiles and have the same bulk metallicity as the deduced abundances. Both are very He poor stars. The light elements are mostly solar except for silicon, and all the heavier elements, except nickel in HD 133029 which is solar, are greatly overabundant. The iron peak elements are typically 10 times overabundant. SrYZr are of order of 100 times solar. The rare earths are 1000 or more times overabundant.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A58
- Title:
- HD20794, HD85512, HD192310 HARPS radial velocities
- Short Name:
- J/A+A/534/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2009 we started, within the dedicated HARPS-Upgrade GTO program, an intense radial-velocity monitoring of a few nearby, slowly-rotating and quiet solar-type stars. The goal of this campaign is to gather, with high cadence and continuity, very-precise radial-velocity data in order to detect tiny signatures of very-low-mass stars potentially in the habitable zone of their parent stars. 10 stars have been selected among the most stable stars of the original HARPS high-precision program, uniformly spread in hour angle, such that three to four of them are observable at any time of the year. For each star we record 50 data points spread over the observing season. The data point consists of three nightly observations of a total integration time of 10 minutes each and separated by 2 hours. This is an observational strategy adopted to minimize stellar pulsation and granulation noise. In this paper we present the first results of this ambitious program. The radial-velocity data and the orbital parameters of five new and one confirmed low-mass planets around the stars HD 20794, HD 85512 and HD 192310, respectively, are reported and discussed, among which a system of three super-Earths and one harboring a 3.6-Earth-mass planet at the inner edge of the habitable zone. This result already confirms previous indications that low-mass planets seem to be very frequent around solar-type stars and that this occurrence frequency may be higher than 30%.
- ID:
- ivo://CDS.VizieR/J/A+A/542/L32
- Title:
- HD 202850 HeI and SiII spectra
- Short Name:
- J/A+A/542/L32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photospheric lines of B-type supergiants show variability in their profile shapes. In addition, their widths are much wider than can be accounted for purely by stellar rotation. This excess broadening is often referred to as macroturbulence. Both effects have been linked to stellar oscillations, but B supergiants have not been systematically searched yet for the presence of especially short-term variability caused by stellar pulsations. We have started an observational campaign to investigate the line profile variability of photospheric lines in a sample of Galactic B supergiants. These observations aim to improve our understanding of the physical effects acting in the atmospheres of evolved massive stars.