High-precision Radial Velocity Research Articles

A low-mass sub-Neptune planet transiting the bright active star HD 73344

Context. Planets with radii of between 2 and 4 R⊕ closely orbiting solar-type stars are of significant importance for studying the transition from rocky to giant planets, and are prime targets for atmospheric characterization by missions such as JWST and ARIEL. Unfortunately, only a handful of examples with precise mass measurements are known to orbit bright stars. Aims. Our goal is to determine the mass of a transiting planet around the very bright F6 star HD 73344 (Vmag = 6.9). This star exhibits high activity and has a rotation period that is close to the orbital period of the planet (Pb = 15.6 days). Methods. The transiting planet, initially a K2 candidate, is confirmed through TESS observations (TOI 5140.01). We refined its parameters using TESS data and rule out a false positive with Spitzer observations. We analyzed high-precision radial velocity (RV) data from the SOPHIE and HIRES spectrographs. We conducted separate and joint analyses of K2, TESS, SOPHIE, and HIRES data using the PASTIS software. Given the star’s early type and high activity, we used a novel observing strategy, targeting the star at high cadence for two consecutive nights with SOPHIE to understand the short-term stellar variability. We modeled stellar noise with two Gaussian processes: one for rotationally modulated stellar processes, and one for short-term stellar variability. Results. High-cadence RV observations provide better constraints on stellar variability and precise orbital parameters for the transiting planet: a radius of Rb = 2.88−0.07+0.08 R⊕ and a mass of Mb = 2.98−1.90+2.50 M⊕ (upper-limit at 3σ is <10.48 M⊕). The derived mean density suggests a sub-Neptune-type composition, but uncertainties in the planet’s mass prevent a detailed characterization. In addition, we find a periodic signal in the RV data that we attribute to the signature of a nontransiting exoplanet, without totally excluding the possibility of a nonplanetary origin. This planetary candidate would have a minimum mass of about Mc sin ic = 116.3 ± −13.0+12.8 M⊕ and a period of Pc = 66.45−0.25+0.10 days. Dynamical analyses confirm the stability of the two-planet system and provide constraints on the inclination of the candidate planet; these findings favor a near-coplanar system. Conclusions. While the transiting planet orbits the bright star at a short period, stellar activity prevented us from precise mass measurements despite intensive RV follow-up. Long-term RV tracking of this planet could improve this measurement, as well as our understanding of the activity of the host star. The latter will be essential if we are to characterize the atmosphere of planets around F-type stars using transmission spectroscopy.

Adaptive median filter salt and pepper noise suppression approach for common path coherent dispersion spectrometer

The Common-path Coherent-dispersion Spectrometer (CODES), an exoplanet detection instrument, executes high-precision Radial Velocity (RV) inversions by recording the phase shifts of interference fringes. Salt-and-pepper noise caused by factors such as improper operation of the CCD probe/analog-to-digital converter and strong dark currents may interfere with the phase information of the fringe. This lowers the quality of the interfering fringe image and significantly interferes with the RV’s inversion. In this study, an adaptive median filtering algorithm (CODESmF) based on submaximum and subminimum values is designed to eliminate the interference fringe image's salt-and-pepper noise as well as to reduce RV error. This allows the interference fringe image's phase information to be retained more completely. The algorithm consists of two major modules. Pixel Sub-extreme-based Filtered Noise Monitoring Module: discriminates signal pixels and noise pixels based on the submaximum and subminimum values of the pixels in the filtering window. Adaptive Median Filter Noise Suppression Module: the signal pixel is kept at the original value output, the noise pixel serves as the filtering window's center pixel, and the adaptive median filtering procedure is repeated numerous times with various filtering window sizes. According to the experimental findings, the CODESmF outperforms comparable algorithms and works better at recovering interference fringes. More than 90% of the phase/RV error caused by salt-and-pepper noise is typically eliminated by the CODESmF algorithm, and in certain circumstances, it can even remove roughly 98% of the phase error.

Early Results from the HUMDRUM Survey: A Small, Earth-mass Planet Orbits TOI-1450A

M-dwarf stars provide us with an ideal opportunity to study nearby small planets. The HUnting for M Dwarf Rocky planets Using MAROON-X (HUMDRUM) survey uses the MAROON-X spectrograph, which is ideally suited to studying these stars, to measure precise masses of a volume-limited (<30 pc) sample of transiting M-dwarf planets. TOI-1450 is a nearby (22.5 pc) binary system containing a M3 dwarf with a roughly 3000 K companion. Its primary star, TOI-1450A, was identified by the Transiting Exoplanet Survey Satellite (TESS) to have a 2.04 days transit signal, and is included in the HUMDRUM sample. In this paper, we present MAROON-X radial velocities (RVs) which confirm the planetary nature of this signal and measure its mass at nearly 10% precision. The 2.04 days planet, TOI-1450A b, has R b = 1.13 ± 0.04 R ⊕ and M b = 1.26 ± 0.13 M ⊕. It is the second-lowest-mass transiting planet with a high-precision RV mass measurement. With this mass and radius, the planet’s mean density is compatible with an Earth-like composition. Given its short orbital period and slightly sub-Earth density, it may be amenable to JWST follow-up to test whether the planet has retained an atmosphere despite extreme heating from the nearby star. We also discover a nontransiting planet in the system with a period of 5.07 days and a Msinic=1.53±0.18M⊕ . We also find a 2.01 days signal present in the systems’s TESS photometry that likely corresponds to the rotation period of TOI-1450A’s binary companion, TOI-1450B. TOI-1450A, meanwhile, appears to have a rotation period of approximately 40 days, which is in line with our expectations for a mid-M dwarf.

The GAPS programme at TNG

Aims. We report the confirmation of a new transiting exoplanet orbiting the star TOI-5076. Methods. We present our vetting procedure and follow-up observations which led to the confirmation of the exoplanet TOI-5076b. In particular, we employed high-precision TESS photometry, high-angular-resolution imaging from several telescopes, and high-precision radial velocities from HARPS-N. Results. From the HARPS-N spectroscopy, we determined the spectroscopic parameters of the host star: Teff = (5070±143) K, log 𝑔 = (4.6±0.3), [Fe/H] = (+0.20±0.08), and [α/Fe] = 0.05±0.06. The transiting planet is a warm sub-Neptune with a mass mp = (16±2) M⊙, a radius rp =(3.2±0.l) R⊙ yielding a density ρp = (2.8±0.5) g cm−3. It revolves around its star approximately every 23.445 days. Conclusions. The host star is a metal-rich, K2V dwarf, located at about 82 pc from the Sun with a radius of R⋆ = (0.78±0.01) R⊙ and a mass of M⋆ = (0.80±0.07) M⊙. It forms a common proper motion pair with an M-dwarf companion star located at a projected separation of 2178 au. The chemical analysis of the host-star and the Galactic-space velocities indicate that TOI-5076 belongs to the old population of thin-to-thick-disk transition stars. The density of TOI-5076b suggests the presence of a large fraction by volume of volatiles overlying a massive core. We found that a circular orbit solution is marginally favored with respect to an eccentric orbit solution for TOI-5076b.

Trio of super-Earth candidates orbiting K-dwarf HD 48948: a new habitable zone candidate

ABSTRACT We present the discovery of three super-Earth candidates orbiting HD 48948, a bright K-dwarf star with an apparent magnitude of $m_V$ = 8.58 mag. As part of the HARPS-N Rocky Planet Search programme, we collect 189 high-precision radial velocity measurements using the HARPS-N spectrograph from 2013 October 6, to 2023 April 16. Various methodologies are applied to extract the radial velocities from the spectra, and we conduct a comprehensive comparative analysis of the outcomes obtained through these diverse extraction techniques. To ensure the robustness of our findings, we employ several methods to address stellar variability, with a focus on Gaussian Process regression. To account for the impact of stellar variability and correlated noise in the radial velocity data set, we include activity indicators, such as $\log R^{^{\prime }}_{\mathrm{HK}}$ and bisector span, in the multidimensional Gaussian Process regression. Our analysis reveals three planetary candidates with orbital periods of 7.3, 38, and 151 d, and minimum masses estimated at $4.88 \pm 0.21$ M$_{\oplus }$, $7.27 \pm 0.70$ M$_{\oplus }$, and $10.59 \pm 1.00$ M$_{\oplus }$, respectively. The outermost planet resides within the (temperate) habitable zone, positioned at a projected distance of $0.029\,{\rm arcsec}$ from its star. Given the close proximity of this planetary system, situated at a distance of 16.8 parsecs, HD 48498 emerges as a promising target (closest super-Earth around FGK stars) for future high-contrast direct imaging and high-resolution spectroscopic studies.

Three short-period Earth-sized planets around M dwarfs discovered by TESS: TOI-5720 b, TOI-6008 b, and TOI-6086 b

One of the main goals of the NASA Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of Earth-like planets around nearby M-dwarf stars. We present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M dwarfs: TOI-5720\,b, TOI-6008\,b, and TOI-6086\,b. We combined TESS data, ground-based multicolor light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD radial velocity data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720\,b is an Earth-sized planet with a radius of $R_p = 1.09 0.07 R_ It orbits a nearby (36 pc) M2.5 host with an orbital period of $P = 1.4344555 0.0000036 $ days. It has an equilibrium temperature of eq 19$ K (assuming a null albedo) and an incident flux of $S_p = 41.7 4.5 S_ TOI-6008\,b is a short-period planet of $ P = 0.8574347 0.0000424$ day. It has a radius of $R_p = 1.03 0.05 R_ an equilibrium temperature of eq 19$ K, and an incident flux of $S_p = 41.5 4.5 S_ The host star (TOI-6008) is a nearby (23 pc) M5 with an effective temperature of eff 75 K$. Based on the radial velocity measurements collected with Subaru/IRD, we set a $3 upper limit of $M_p &lt; 4M_ thus ruling out a star or brown dwarf as the transiting companion. TOI-6086\,b orbits its nearby (32 pc) M3 host star eff 75$ K) every $1.3888725 0.0000827$ days and has a radius of $ R_p = 1.18 0.07 R_ an equilibrium temperature of eq 16$ K, and an incident flux of $S_p = 26.8 2.7 S_ Additional high-precision radial velocity measurements are needed to derive the planetary masses and bulk densities and to search for additional planets in the systems. Moreover, short-period Earth-sized planets orbiting around nearby M dwarfs are suitable targets for an atmospheric characterization with the James Webb Space Telescope through transmission and emission spectroscopy and phase-curve photometry.

VELOcities of CEpheids (VELOCE). I. High-precision radial velocities of Cepheids

We present the first data release of VELOcities of CEpheids ( dedicated to measuring the high-precision radial velocities (RVs) of Galactic classical Cepheids (henceforth, Cepheids). The first data release ( DR1) comprises RV measurements of bona fide classical Cepheids on both hemispheres collected mainly between 2010 and 2022, along with observations of stars, most of which had previously been misclassified as Cepheids. The median per-observation RV uncertainty for Cepheids is and reaches $2\,$ for the brightest stars observed with Non-variable standard stars were used to characterize RV zero-point stability and to provide a base for future cross-calibrations. We determined zero-point differences between and 31 literature data sets using template fitting, which we also used to investigate linear period changes of Cepheids. In total, 76 spectroscopic binary Cepheids and 14 candidate binary Cepheids were identified using data alone, which are investigated in detail in a companion paper ( II). DR1 provides a number of new insights into the pulsational variability of Cepheids, most importantly: a) the most detailed description of the Hertzsprung progression based on RVs to date; b) the identification of double-peaked bumps in the pulsation curve; and c) clear evidence that virtually all Cepheids feature spectroscopic variability signals that lead to modulated RV variability at the level of tens to hundreds of and that cannot be satisfactorily modeled using single-periodic Fourier series. We identified stars exhibiting such modulated variability, of which 4 also exhibit orbital motion. Linear radius variations depend strongly on pulsation period and a steep increase in slope of the $ R/p$ versus $ P -$relation is found near $10$\,d. This effect, combined with significant RV amplitude differences at fixed period, challenges the existence of a tight relation between Baade-Wesselink projection factors and pulsation periods. We investigated the accuracy of RV time series measurements and RV amplitudes published by third data release ( \ DR3) and determined an offset of $0.65 relative to Whenever possible, we recommend adopting a single set of template correlation parameters for distinct classes of large-amplitude variable stars to avoid systematic offsets in among stars belonging to the same class. The peak-to-peak amplitudes of exhibit significant ($16&lt;!PCT!&gt;$) dispersion. Potential differences of RV amplitudes require further inspection, notably in the context of projection factor calibration.

Orbital obliquity of the young planet TOI-5398 b and the evolutionary history of the system

Multi-planet systems exhibit remarkable architectural diversity. However, short-period giant planets are typically isolated. Compact systems like TOI-5398, with an outer close-orbit giant and an inner small-size planet, are rare among systems containing short-period giants. TOI-5398’s unusual architecture coupled with its young age (650 ± 150 Myr) make it a promising system for measuring the original obliquity between the orbital axis of the giant and the stellar spin axis in order to gain insight into its formation and orbital migration. We collected in-transit (plus suitable off-transit) observations of TOI-5398 b with HARPS-N at TNG on March 25, 2023, obtaining high-precision radial velocity time series that allowed us to measure the Rossiter-McLaughlin (RM) effect. By modelling the RM effect, we obtained a sky-projected obliquity of λ = 3.0−4.2+6.8 deg for TOI-5398 b, consistent with the planet being aligned. With knowledge of the stellar rotation period, we estimated the true 3D obliquity, finding ψ = (13.2 ± 8.2) deg. Based on theoretical considerations, the orientation we measure is unaffected by tidal effects, offering a direct diagnostic for understanding the formation path of this planetary system. The orbital characteristics of TOI-5398, with its compact architecture, eccentricity consistent with circular orbits, and hints of orbital alignment, appear more compatible with the disc-driven migration scenario. TOI-5398, with its relative youth (compared with similar compact systems) and exceptional suitability for transmission spectroscopy studies, presents an outstanding opportunity to establish a benchmark for exploring the disc-driven migration model.

The compact multi-planet system GJ 9827 revisited with ESPRESSO

GJ 9827 is a bright, nearby K7V star orbited by two super-Earths and one mini-Neptune on close-in orbits. The system was first discovered using K2 data and then further characterized by other spectroscopic and photometric instruments. Previous literature studies provide several mass measurements for the three planets, however, with large variations and uncertainties. To better constrain the planetary masses, we added high-precision radial velocity measurements from ESPRESSO to published datasets from HARPS, HARPS-N, and HIRES and we performed a Gaussian process analysis combining radial velocity and photometric datasets from K2 and TESS. This method allowed us to model the stellar activity signal and derive precise planetary parameters. We determined planetary masses of Mb = 4.28−0.33+0.35 M⊕, Mc = 1.86−0.39+0.37 M⊕, and Md = 3.02−0.57+0.58 M⊕, and orbital periods of 1.208974 ± 0.000001 days for planet b, 3.648103−0.000010+0.000013 days for planet c, and 6.201812 ± 0.000009 days for planet d. We compared our results to literature values and found that our derived uncertainties for the planetary mass, period, and radial velocity amplitude are smaller than the previously determined uncertainties. We modeled the interior composition of the three planets using the machine-learning-based tool ExoMDN and conclude that GJ 9827 b and c have an Earth-like composition, whereas GJ 9827 d has an hydrogen envelope, which, together with its density, places it in the mini-Neptune regime.

TOI-1199 b and TOI-1273 b: Two new transiting hot Saturns detected and characterized with SOPHIE and TESS

We report the characterization of two planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with periods of 3.7 and 4.6 days, respectively. Follow-up observations for both targets, which include several ground-based light curves, confirmed the transit events. High-precision radial velocities from the SOPHIE spectrograph revealed signals at the expected frequencies and phases of the transiting candidates and allowed mass determinations with a precision of 8.4% and 6.7% for TOI-1199 b and TOI-1273 b, respectively. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We find that the planets have masses of 0.239 ± 0.020 MJ and 0.222 ± 0.015 MJ and radii of 0.938 ± 0.025 RJ and 0.99 ± 0.22 RJ, respectively. The grazing transit of TOI-1273 b translates to a larger uncertainty in its radius, and hence also in its bulk density, compared to TOI-1199 b. The inferred bulk densities of 0.358 ± 0.041 g cm−3 and 0.28 ± 0.11 g cm−3 are among the lowest known for exoplanets in this mass range, which, considering the brightness of the host stars (V≈11 mag), render them particularly amenable to atmospheric characterization via the transit spectroscopy technique. The better constraints on the parameters of TOI-1199 b provide a transmission spectroscopy metric of 134 ± 17, making it the better suited of the two planets for atmospheric studies.

The PFS View of TOI-677 b: A Spin–Orbit Aligned Warm Jupiter in a Dynamically Hot System* *This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

TOI-677 b is part of an emerging class of “tidally detached” gas giants (a/R ⋆ ≳ 11) that exhibit large orbital eccentricities and yet low stellar obliquities. Such sources pose a challenge for models of giant planet formation, which must account for the excitation of high eccentricities without large changes in the orbital inclination. In this work, we present a new Rossiter–McLaughlin measurement of the tidally detached warm Jupiter TOI-677 b, obtained using high-precision radial velocity observations with Magellan’s Planet Finder Spectrograph (PFS). Combined with previously published observations from the Very Large Telescope’s ESPRESSO spectrograph, we derive one of the most precisely constrained sky-projected spin–orbit angle measurements to date for an exoplanet. The combined fit offers a refined set of self-consistent parameters, including a low sky-projected stellar obliquity of λ=3.°2−1.∘5+1.∘6 and a moderately high eccentricity of e=0.460−0.018+0.019 , which further constrain the puzzling architecture of this system. We examine several potential scenarios that may have produced the current TOI-677 orbital configuration, ultimately concluding that TOI-677 b most likely had its eccentricity excited through disk–planet interactions. This system adds to a growing population of aligned warm Jupiters on eccentric orbits around hot (T eff > 6100 K) stars.

TOI-4438 b: a transiting mini-Neptune amenable to atmospheric characterization

We report the confirmation and mass determination of a mini-Neptune transiting the M3.5\,V star TOI-4438 (G 182-34) every 7.44 days. A transit signal was detected with NASA's TESS space mission in the sectors 40, 52, and 53. In order to validate the planet TOI-4438\,b and to determine the system properties, we combined TESS data with high-precision radial velocity measurements from the CARMENES spectrograph, spanning almost one year, and ground-based transit photometry. We found that TOI-4438\,b has a radius of $R_ b $\,=\,2.52\,pm \,0.13 R$_ (5&lt;!PCT!&gt; precision), which together with a mass of $M_ b $\,=\,5.4\,pm \,1.1 M$_ (20&lt;!PCT!&gt; precision), results in a bulk density of $ b $ (sim 28&lt;!PCT!&gt; precision), aligning the discovery with a volatile-rich planet. Our interior structure retrieval with a pure water envelope yields a minimum water mass fraction of 46&lt;!PCT!&gt; (1sigma ). TOI-4438\,b is a volatile-rich mini-Neptune with likely H/He mixed with molecules, such as water, CO$_2$, and CH$_4$. The primary star has a $J$-band magnitude of 9.7, and the planet has a high transmission spectroscopy metric (TSM) of 136\,pm \,13. Taking into account the relatively warm equilibrium temperature of $T_ eq $\,=\,435\,pm \,15 K, and the low activity level of its host star, TOI-4438\,b is one of the most promising mini-Neptunes around an M dwarf for transmission spectroscopy studies.

Analysis of the public HARPS/ESO spectroscopic archive

Context. Magnetic activity is currently the primary limiting factor in radial velocity (RV) exoplanet searches. Even inactive stars, such as the Sun, exhibit RV jitter of the order of a few m s−1 due to active regions on their surfaces. Time series of chromospheric activity indicators, such as the Ca II H&amp;K lines, can be utilized to reduce the impact of such activity phenomena on exoplanet search programmes. In addition, the identification and correction of instrumental effects can improve the precision of RV exoplanet surveys. Aims. We aim to update the HARPS -RVBANK RV database and include an additional 3.5 yr of time series and Ca II H&amp;K lines (R′HK) chromospheric activity indicators. This additional data will aid in the analysis of the impact of stellar magnetic activity on the RV time series obtained with the HARPS instrument. Our updated database aims to provide a valuable resource for the exoplanet community in understanding and mitigating the effects of such stellar magnetic activity on RV measurements. Methods. The new HARPS-RVBANK database includes all stellar spectra obtained with the HARPS instrument prior to January 2022. The RVs corrected for small but significant nightly zero-point variations were calculated using an established method. The R′HK estimates were determined from both individual spectra and co-added template spectra with the use of model atmospheres. As input for our derivation of R′HK, we derived stellar parameters from co-added, high signal-to-noise ratio templates for a total of 3230 stars using the stellar parameter code SPECIES. Results. The new version of the HARPS RV database has a total of 252 615 RVs of 5239 stars. Of these, 195 387 have R′HK values, which corresponds to 77% of all publicly available HARPS spectra. Currently, this is the largest public database of high-precision (down to ~1 m s−1) RVs, and the largest compilation of R′HK measurements. We also derived lower limits for the RV jitter of F-, G-, and K-type stars as a function of R′HK.

The 3D Kinematics of the Orion Nebula Cluster. II. Mass-dependent Kinematics of the Inner Cluster

We present the kinematic analysis of 246 stars within 4′ from the center of Orion Nebula Cluster (ONC), the closest massive star cluster with active star formation across the full mass range, which provides valuable insights in the formation and evolution of star cluster on an individual-star basis. High-precision radial velocities and surface temperatures are retrieved from spectra acquired by the NIRSPEC instrument used with adaptive optics (NIRSPAO) on the Keck II 10 m telescope. A 3D kinematic map is then constructed by combining with the proper motions previously measured by the Hubble Space Telescope Advanced Camera for Surveys/WFPC2/WFC3IR and Keck II NIRC2. The measured root-mean-squared velocity dispersion is 2.26 ± 0.08 km s−1, significantly higher than the virial equilibrium’s requirement of 1.73 km s−1, suggesting that the ONC core is supervirial, consistent with previous findings. Energy equipartition is not detected in the cluster. Most notably, the velocity of each star relative to its neighbors is found to be negatively correlated with stellar mass. Low-mass stars moving faster than their surrounding stars in a supervirial cluster suggests that the initial masses of forming stars may be related to their initial kinematic states. Additionally, a clockwise rotation preference is detected. A weak sign of inverse mass segregation is also identified among stars excluding the Trapezium stars, although it could be a sample bias. Finally, this study reports the discovery of four new candidate spectroscopic binary systems.

ESPRESSO Observations of Gaia BH1: High-precision Orbital Constraints and no Evidence for an Inner Binary

We present high-precision radial velocity observations of Gaia BH1, the nearest known black hole (BH). The system contains a solar-type G star orbiting a massive dark companion, which could be either a single BH or an inner BH + BH binary. A BH + BH binary is expected in some models where Gaia BH1 formed as a hierarchical triple, which is attractive because they avoid many of the difficulties associated with forming the system through isolated binary evolution. Our observations test the inner binary scenario. We have measured 115 precise RVs of the G star, including 40 from ESPRESSO with a precision of 3–5 m s−1, and 75 from other instruments with a typical precision of 30–100 m s−1. Our observations span 2.33 orbits of the G star and are concentrated near a periastron passage, when perturbations due to an inner binary would be largest. The RVs are well-fit by a Keplerian two-body orbit and show no convincing evidence of an inner binary. Using REBOUND simulations of hierarchical triples with a range of inner periods, mass ratios, eccentricities, and orientations, we show that plausible inner binaries with periods P inner ≳ 1.5 days would have produced larger deviations from a Keplerian orbit than observed. Binaries with P inner ≲ 1.5 days are consistent with the data, but these would merge within a Hubble time and would thus imply fine-tuning. We present updated parameters of Gaia BH1's orbit. The RVs yield a spectroscopic mass function fMBH=3.9358±0.0002M⊙ —about 7000σ above the ∼2.5 M ⊙ maximum neutron star mass. Including the inclination constraint from Gaia astrometry, this implies a BH mass of M BH = 9.27 ± 0.10 M ⊙.

The California Legacy Survey. IV. Lonely, Poor, and Eccentric: A Comparison between Solitary and Neighborly Gas Giants

We compare systems with single giant planets to systems with multiple giant planets using a catalog of planets from a high-precision radial velocity survey of FGKM stars. Our comparison focuses on orbital properties, planet masses, and host-star properties. We use hierarchical methods to model the orbital eccentricity distributions of giant singles and giant multiples, and find that the distributions are distinct. The multiple giant planets typically have moderate eccentricities and their eccentricity distribution extends to e = 0.47 (90th percentile), while the single giant planets have a pileup of nearly circular orbits and a long tail that extends to e = 0.77. We determine that the stellar hosts of multiple giants are distinctly more metal rich than the hosts of solitary giants, with respective mean metallicities of 0.228 ± 0.027 versus 0.129 ± 0.019 dex. We measure the distinct occurrence distributions of single and multiple giants with respect to orbital separation, and find that single gas giants have a ∼2.3σ significant hot Jupiter (a < 0.06) pileup not seen among multigiant systems. We find that the median mass () of giants in multiples is nearly double that of single giants (1.71 M J versus 0.92 M J). We find that giant planets in the same system have correlated masses, analogous to the “peas in a pod” effect seen among less-massive planets.

Dynamics of Photospheric Magnetic Flux Distribution and Variations in Solar RVs: A Study Using HARPS-N Solar and SDO Observations

The distribution and evolution of photospheric magnetic fields in sunspots, plages, and network, and variations in their relative flux content, play key roles in radial velocity (RV) fluctuations observed in Sun-as-a-star spectra. Differentiating and disentangling such magnetic contributions to RVs help in building models to account for stellar activity signals in high-precision RV exoplanet searches. In this work, as earlier authors, we employ high-resolution images of the solar magnetic field and continuum intensities from SDO/HMI to understand the activity contributions to RVs from HARPS-N solar observations. Using well-observed physical relationships between strengths and fluxes of photospheric magnetic fields, we show that the strong fields (spots, plages, and network) and the weak inter-network fields leave distinguishing features in their contributions to the RV variability. We also find that the fill factors and average unsigned magnetic fluxes of different features correlate differently with the RVs and hence warrant care in employing either of them as a proxy for RV variations. In addition, we examine disk-averaged UV intensities at 1600 and 1700 Å wavelength bands imaged by SDO/AIA and their performances as proxies for variations in different magnetic features. We find that the UV intensities provide a better measure of contributions of plage fields to RVs than the Ca ii H-K emission indices, especially during high activity levels when the latter tend to saturate.

The Orbit of Warm Jupiter WASP-106 b is Aligned with its Star

Understanding orbital obliquities, or the misalignment angles between a star’s rotation axis and the orbital axis of its planets, is crucial for unraveling the mechanisms of planetary formation and migration. In this study, we present an analysis of Rossiter–McLaughlin (RM) observations of the warm Jupiter exoplanet WASP-106 b. The high-precision radial velocity measurements were made with HARPS and HARPS-N during the transit of this planet. We aim to constrain the orientation of the planet’s orbit relative to its host star’s rotation axis. The RM observations are analyzed using a code which models the RM anomaly together with the Keplerian orbit given several parameters in combination with a Markov chain Monte Carlo implementation. We measure the projected stellar obliquity in the WASP-106 system for the first time and find λ = (−1 ± 11)°, supporting the theory of quiescent migration through the disk.

The GAPS programme at TNG

Context. With the growth of comparative exoplanetology, it is increasingly clear that the relationship between inner and outer planets plays a key role in unveiling the mechanisms governing formation and evolution models. For this reason, it is important to probe the inner region of systems hosting long-period giants in search of undetected lower mass planetary companions. Aims. We aim to present the results of a high-cadence and high-precision radial velocity (RV) monitoring of three late-type dwarf stars hosting long-period giants with well-measured orbits in order to search for short-period sub-Neptunes (SN, M sin i &lt; 30 M⊕). Methods. Building on the results and expertise of our previous studies, we carried out combined fits of our HARPS-N data with literature RVs. We used Markov chain Monte Carlo (MCMC) analyses to refine the literature orbital solutions and search for additional inner planets, applying Gaussian process regression techniques to deal with the stellar activity signals where required. We then used the results of our survey to estimate the frequency of sub-Neptunes in systems hosting cold Jupiters, f(SN|CJ), and compared it with the frequency around field M dwarfs, f(SN). Results. We identify a new short-period, low-mass planet orbiting GJ 328, GJ 328 c, with Pc = 241.8-1.7+1.3 days and Mc sin i = 21.4-3.2+3.4M⊕. We moreover identify and model the chromospheric activity signals and rotation periods of GJ 649 and GJ 849, around which no additional planet is found. Then, taking into account also planetary system around the previously analysed low-mass star BD-11 4672, we derive an estimate of the frequencies of inner planets in such systems. In particular, f(SN|CJ) = 0.25-0.07+0.58 for mini-Neptunes (10 M⊕ &lt; M sin i &lt; 30 M⊕, P &lt; 150 d), marginally larger than f(SN). For lower mass planets (M sin i &lt; 10 M⊕) instead f(SN|CJ) &lt; 0.69, which is compatible with f(SN). Conclusions. In light of the newly detected mini-Neptune, we find tentative evidence of a positive correlation between the presence of long-period giant planets and that of inner low-mass planets, f(SN|CJ) &gt; f(SN). This might indicate that cold Jupiters have an opposite influence in the formation of inner sub-Neptunes around late-type dwarfs as opposed to their solar-type counterparts, boosting the formation of mini-Neptunes instead of impeding it.

Sub-m s−1 upper limits from a deep HARPS-N radial-velocity search for planets orbiting HD 166620 and HD 144579

ABSTRACT Minimizing the impact of stellar variability in radial velocity (RV) measurements is a critical challenge in achieving the 10 cm s−1 precision needed to hunt for Earth twins. Since 2012, a dedicated programme has been underway with HARPS-N, to conduct a blind RV rocky planets search (RPS) around bright stars in the Northern hemisphere. Here we describe the results of a comprehensive search for planetary systems in two RPS targets, HD 166620 and HD 144579. Using wavelength-domain line-profile decorrelation vectors to mitigate the stellar activity and performing a deep search for planetary reflex motions using a trans-dimensional nested sampler, we found no significant planetary signals in the data sets of either of the stars. We validated the results via data-splitting and injection recovery tests. Additionally, we obtained the 95th percentile detection limits on the HARPS-N RVs. We found that the likelihood of finding a low-mass planet increases noticeably across a wide period range when the inherent stellar variability is corrected for using scalpelsU-vectors. We are able to detect planet signals with Msin i ≤ 1 M⊕ for orbital periods shorter than 10 d. We demonstrate that with our decorrelation technique, we are able to detect signals as low as 54 cm s−1, which brings us closer to the calibration limit of 50 cm s−1 demonstrated by HARPS-N. Therefore, we show that we can push down towards the RV precision required to find Earth analogues using high-precision radial velocity data with novel data-analysis techniques.