- ID:
- ivo://CDS.VizieR/J/AJ/162/181
- Title:
- RVel & Hipparcos positions of epsilon Eridani
- Short Name:
- J/AJ/162/181
- Date:
- 14 Mar 2022 06:39:08
- Publisher:
- CDS
- Description:
- {epsilon}Eridani is a young planetary system hosting a complex multibelt debris disk and a confirmed Jupiter-like planet orbiting at 3.48au from its host star. Its age and architecture are thus reminiscent of the early Solar System. The most recent study of Mawet et al., which combined radial-velocity data and Ms-band direct imaging upper limits, started to constrain the planet's orbital parameters and mass, but are still affected by large error bars and degeneracies. Here we make use of the most recent data compilation from three different techniques to further refine {epsilon}Eridani b's properties: RVs, absolute astrometry measurements from the Hipparcos and Gaia missions, and new Keck/NIRC2 Ms-band vortex coronagraph images. We combine this data in a Bayesian framework. We find a new mass, M_b_=0.66_-0.09_^+0.12^M_Jup_, and inclination, i=78.81_-22.41_^+29.34^deg, with at least a factor 2 of improvement over previous uncertainties. We also report updated constraints on the longitude of the ascending node, the argument of the periastron, and the time of periastron passage. With these updated parameters, we can better predict the position of the planet at any past and future epoch, which can greatly help define the strategy and planning of future observations and with subsequent data analysis. In particular, these results can assist the search for a direct detection with JWST and the Nancy Grace Roman Space Telescope's coronagraph instrument.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/639/A35
- Title:
- RV jitter and photometric var. correlation
- Short Name:
- J/A+A/639/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Characterizing the relation between stellar photometric variability and radial velocity (RV) jitter can help us to better understand the physics behind these phenomena. The current and upcoming high precision photometric surveys such as TESS, CHEOPS, and PLATO will provide the community with thousands of new exoplanet candidates. As a consequence, the presence of such a correlation is crucial in selecting the targets with the lowest RV jitter for efficient RV follow-up of exoplanetary candidates. Studies of this type are also crucial to design optimized observational strategies to mitigate RV jitter when searching for Earth-mass exoplanets. Aims. Our goal is to assess the correlation between high-precision photometric variability measurements and high-precision RV jitter over different time scales. We analyze 171 G, K, and M stars with available TESS high precision photometric time-series and HARPS precise RVs. We derived the stellar parameters for the stars in our sample and measured the RV jitter and photometric variability. We also estimated chromospheric CaII H & K activity indicator log(R'_HK_), vsini, and the stellar rotational period. Finally, we evaluate how different stellar parameters and an RV sampling subset can have an impact on the potential correlations. We find a varying correlation between the photometric variability and RV jitter as function of time intervals between the TESS photometric observation and HARPS RV. As the time intervals of the observations considered for the analysis increases, the correlation value and significance becomes smaller and weaker, to the point that it becomes negligible. We also find that for stars with a photometric variability above 6.5 ppt the correlation is significantly stronger. We show that such a result can be due to the transition between the spot-dominated and the faculae-dominated regime. We quantified the correlations and updated the relationship between chromospheric CaII H & K activity indicator log(R'_HK_) and RV jitter.
- ID:
- ivo://CDS.VizieR/J/AJ/155/79
- Title:
- RV & light curves data for 4 G-type dwarf stars
- Short Name:
- J/AJ/155/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four close-in transiting exoplanets (HATS-50b through HATS-53b), discovered using the HATSouth three-continent network of homogeneous and automated telescopes. These new exoplanets belong to the class of hot Jupiters and orbit G-type dwarf stars, with brightness in the range V=12.5-14.0 mag. While HATS-53 has many physical characteristics similar to the Sun, the other three stars appear to be metal-rich ([Fe/H]=0.2-0.3), larger, and more massive. Three of the new exoplanets, namely HATS-50b, HATS-51b, and HATS-53b, have low density (HATS-50b: 0.39+/-0.10 M_J_, 1.130+/-0.075 R_J_; HATS-51b: 0.768+/-0.045 M_J_, 1.41+/-0.19 R_J_; HATS-53b: 0.595+/-0.089 M_J_, 1.340+/-0.056 R_J_) and similar orbital periods (3.8297 days, 3.3489 days, 3.8538 days, respectively). Instead, HATS-52b is more dense (mass 2.24+/-0.15 M_J_ and radius 1.382+/-0.086 R_J_) and has a shorter orbital period (1.3667 days). It also receives an intensive radiation from its parent star and, consequently, presents a high equilibrium temperature (T_eq_=1834+/-73 K). HATS-50 shows a marginal additional transit feature consistent with an ultra-short-period hot super Neptune (upper mass limit 0.16 M_J_), which will be able to be confirmed with TESS photometry.
- ID:
- ivo://CDS.VizieR/J/AJ/156/64
- Title:
- RV measurements for 6 K giants in the SENS program
- Short Name:
- J/AJ/156/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of long-period radial velocity (RV) variations in six intermediate-mass K-giant stars using precise RV measurements. These discoveries are part of the Search for Exoplanets around Northern Circumpolar Stars (SENS) survey being conducted at the Bohyunsan Optical Astronomy Observatory. The nature of the RV variations was investigated by looking for photometric and line shape variations. We can find no variability with the RV period in these quantities and conclude that RV variations are most likely due to unseen sub-stellar companions. Orbital solutions for the six stars yield orbital periods in the range 418-1065 days and minimum masses in the range 1.9-8.5 M_J_. These properties are typical on planets around intermediate-mass stars. Our SENS survey so far has about an 8% confirmed planet occurrence rate, and it will provide better statistics on planets around giant stars when the survey is completed.
- ID:
- ivo://CDS.VizieR/J/AJ/158/165
- Title:
- RV observations & activity indicators for Kepler-538b
- Short Name:
- J/AJ/158/165
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although several thousands of exoplanets have now been detected and characterized, observational biases have led to a paucity of long-period, low-mass exoplanets with measured masses and a corresponding lag in our understanding of such planets. In this paper we report the mass estimation and characterization of the long-period exoplanet Kepler-538b. This planet orbits a Sun-like star (V=11.27) with M_*_=0.892_-0.035_^+0.051^ M_{sun}_ and R_*_=0.8717_-0.0061_^+0.0064^ R_{sun}_. Kepler-538b is a 2.215_-0.034_^+0.040^ R_{Earth}_ sub-Neptune with a period of P=81.73778+/-0.00013 days. It is the only known planet in the system. We collected radial velocity (RV) observations with the High Resolution Echelle Spectrometer (HIRES) on Keck I and High Accuracy Radial velocity Planet Searcher in North hemisphere (HARPS-N) on the Telescopio Nazionale Galileo (TNG). We characterized stellar activity by a Gaussian process with a quasi-periodic kernel applied to our RV and cross-correlation function FWHM observations. By simultaneously modeling Kepler photometry, RV, and FWHM observations, we found a semi-amplitude of K=1.68_-0.38_^+0.39^ m/s and a planet mass of M_p_=10.6_-2.4_^+2.5^ M_{Earth}_. Kepler-538b is the smallest planet beyond P=50 days with an RV mass measurement. The planet likely consists of a significant fraction of ices (dominated by water ice), in addition to rocks/metals, and a small amount of gas. Sophisticated modeling techniques such as those used in this paper, combined with future spectrographs with ultra high-precision and stability will be vital for yielding more mass measurements in this poorly understood exoplanet regime. This in turn will improve our understanding of the relationship between planet composition and insolation flux and how the rocky to gaseous transition depends on planetary equilibrium temperature.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A17
- Title:
- RV of candidate hybrid variable stars
- Short Name:
- J/A+A/610/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hundreds of candidate hybrid pulsators of intermediate type A-F were revealed by recent space missions. Hybrid pulsators allow us to study the full stellar interiors, where both low-order p- and high-order g-modes are simultaneously excited. The true hybrid stars must be identified since other processes, related to stellar multiplicity or rotation, might explain the presence of (some) low frequencies observed in their periodograms. We measured the radial velocities of 50 candidate delta Scuti - gamma Doradus hybrid stars from the Kepler mission with the Hermes and Ace spectrographs over a time span of months to years. We aim to derive the fraction of binary and multiple systems and to provide an independent and homogeneous determination of the atmospheric properties and v.sini for all targets. The long(er)-term objective is to identify the (probable) physical cause of the low frequencies. We computed one-dimensional cross-correlation functions (CCFs) in order to find the best set of parameters in terms of number of components, spectral type(s), and v.sini for each target. Fundamental parameters were determined by fitting (composite) synthetic spectra to the normalised median spectra corrected for the appropriate Doppler shifts. We report on the analysis of 478 high-resolution Hermes and 41 Ace spectra of A/F-type candidate hybrid pulsators from the Kepler field. We determined their radial velocities, projected rotational velocities, and atmospheric properties and classified our targets based on the shape of the CCFs and the temporal behaviour of the radial velocities. We derived orbital solutions for seven new systems. Three preliminary long-period orbital solutions are confirmed by a photometric time-delay analysis. Finally, we determined a global multiplicity fraction of 27 percent in our sample of candidate hybrid stars.
- ID:
- ivo://CDS.VizieR/J/AJ/140/1337
- Title:
- RV of 111 Galactic halo stars in Virgo
- Short Name:
- J/AJ/140/1337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-slit radial velocity measurements for 111 stars in the direction of the Virgo Stellar Stream (VSS). The stars were photometrically selected to be probable main-sequence stars in the Galactic halo. When compared with the radial velocity distribution expected for the halo of the Milky Way, as well as the distribution seen in a control field, we observe a significant excess of negative velocity stars in the field, which can likely be attributed to the presence of a stellar stream.
- ID:
- ivo://CDS.VizieR/J/MNRAS/356/1583
- Title:
- RV of Sigma Ori low-mass candidate members
- Short Name:
- J/MNRAS/356/1583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities for 38 low-mass candidate members of the {sigma} Orionis young group. We have measured their radial velocities by cross-correlation of high-resolution (R>>6000) AF2/Wide Field Fibre Optical Spectrograph (WYFFOS) spectra of the gravity-sensitive NaI doublet at 8183,8195{AA}, on the nights of 2003 January 3 and 4. The total sample contained 117 objects, of which 54 have sufficient signal-to-noise ratio to detect NaI at an equivalent width of 3{AA}; however, we only detect NaI in 38 of these. This implies that very low-mass members of this young group display weaker NaI absorption than similarly aged objects in the Upper Scorpius OB association. We develop a technique to assess membership using radial velocities with a range of uncertainties that does not bias the selection when large uncertainties are present. The resulting membership probabilities are used to assess the issue of exclusion in photometric selections, and we find that very few members are likely to be excluded by such techniques. We also assess the level of contamination in the expected pre-main-sequence region of colour-magnitude space brighter than I=17. We find that contamination by non-members in the expected pre-main-sequence region of the colour-magnitude diagram is small. We conclude that although radial velocity alone is insufficient to confirm membership, high signal-to-noise ratio observations of the NaI doublet provide the opportunity to use the strength of NaI absorption in concert with radial velocities to asses membership down to the lowest masses, where lithium absorption no longer distinguishes youth.
- ID:
- ivo://CDS.VizieR/J/AN/341/99
- Title:
- RV of 11 spectroscopic binaries
- Short Name:
- J/AN/341/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our second radial velocity (RV) monitoring campaign, carried out with the Echelle spectrograph FLECHAS at the University Observatory Jena in the course of the Grosschwabhausen binary survey between December 2016 and June 2018. The aim of this project is to obtain precise RV measurements for spectroscopic binary stars in order to redetermine, verify, improve, and constrain their Keplerian orbital solutions. In this paper, we describe the observations, data reduction, and analysis and present the results of this project. In total, we have taken 721 RV measurements of 11 stars and derived well-determined orbital solutions for nine systems (seven single- and two double-lined spectroscopic binaries) with periods in the range between 2 and 70 days. In addition, we could rule out the orbital solutions for the previously classified spectroscopic binary systems HIP 107136 and HIP 107533, whose radial velocities are found to be constant on the km/s-level over a span of time of more than 500 days. In the case of HIP 2225, a significant change of its systematic velocity is detected between our individual observing epochs, indicating the presence of an additional companion, which is located on a wider orbit in this system.
- ID:
- ivo://CDS.VizieR/J/A+A/496/513
- Title:
- RV of 6 stars with long-period giant planets
- Short Name:
- J/A+A/496/513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of six new substellar companions of main-sequence stars, detected by multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6m telescope, La Silla, Chile. These extrasolar planets orbit the stars BD-17 0063, HD 20868, HD 73267, HD 131664, HD 145377, and HD 153950. The orbital characteristics that reproduce the observed data are presented, as well as the stellar and planetary parameters. Masses of the companions range from 2 to 18 Jupiter masses, and periods range from 100 to 2000 days. The observational data are carefully analysed for activity-induced effects, and we conclude that the observed radial velocity variations are of exoplanetary origin. Of particular interest is the very massive planet (or brown-dwarf companion) orbiting the metal-rich HD 131664 with m_2_sini=18.15M_{Jup}_ and a 5.34-year orbital period. These new discoveries are consistent with the observed statistical properties of exoplanet samples known so far.
