- ID:
- ivo://CDS.VizieR/J/A+A/573/L5
- Title:
- Radial velocity data of Kepler-432
- Short Name:
- J/A+A/573/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the first disclosure of the planetary nature of Kepler-432 b (aka Kepler object of interest KOI-1299.01). We accurately constrained its mass and eccentricity by high-precision radial velocity measurements obtained with the CAFE spectrograph at the CAHA 2.2-m telescope. By a simultaneous fit of these new data and Kepler photometry, we found that KOI-1299 b is a dense transiting exoplanet, having a mass of Mp=4.87+/-0.48M_Jup_ and radius of Rp=1.120+/-0.036R_Jup_. The planet revolves around a K giant star, ascending the red giant branch, every 52.5d, moving on a highly eccentric orbit with e=0.535+/-0.030. By analysing two NIR high-resolution images, we found that a star occurs at 1:100 from Kepler-432, but it is too faint to cause significant effects on the transit depth. Together with Kepler-56 and Kepler-91, KOI-1299 occupies an almost-desert region of parameter space, which is important to constrain the evolutionary processes of planetary systems.
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- ID:
- ivo://CDS.VizieR/J/AJ/161/283
- Title:
- Radial velocity estimates of 4 stars with IGRINS
- Short Name:
- J/AJ/161/283
- Date:
- 08 Mar 2022
- Publisher:
- CDS
- Description:
- Application of the radial velocity (RV) technique in the near-infrared is valuable because of the diminished impact of stellar activity at longer wavelengths, making it particularly advantageous for the study of late-type stars but also for solar-type objects. In this paper, we present the IGRINS RV open-source python pipeline for computing infrared RV measurements from reduced spectra taken with IGRINS, an R~{lambda}/{Delta}{lambda}~45000 spectrograph with simultaneous coverage of the H-band (1.49-1.80{mu}m) and K-band (1.96-2.46{mu}m). Using a modified forward-modeling technique, we construct high-resolution telluric templates from A0 standard observations on a nightly basis to provide a source of common-path wavelength calibration while mitigating the need to mask or correct for telluric absorption. Telluric standard observations are also used to model the variations in instrumental resolution across the detector, including a yearlong period when the K-band was defocused. Without any additional instrument hardware, such as a gas cell or laser frequency comb, we are able to achieve precisions of 26.8m/s in the K-band and 31.1m/s in the H-band for narrow-line hosts. These precisions are empirically determined by a monitoring campaign of two RV standard stars, as well as the successful retrieval of planet-induced RV signals for both HD189733 and {tau}BooA; furthermore, our results affirm the presence of the Rossiter-McLaughlin effect for HD189733. The IGRINS RV pipeline extends another important science capability to IGRINS, with publicly available software designed for widespread use.
- 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.
- 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/162/117
- 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/AJ/159/235
- Title:
- Radial Velocity jitters in ~600 planet host stars
- Short Name:
- J/AJ/159/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radial velocity (RV) detection of planets is hampered by astrophysical processes on the surfaces of stars that induce a stochastic signal, or "jitter," which can drown out or even mimic planetary signals. Here, we empirically and carefully measure the RV jitter of more than 600 stars from the California Planet Search sample on a star by star basis. As part of this process, we explore the activity-RV correlation of stellar cycles and include appendices listing every ostensibly companion-induced signal we removed and every activity cycle we noted. We then use precise stellar properties from Brewer+, 2017ApJS..230...12B to separate the sample into bins of stellar mass and examine trends with activity and with evolutionary state. We find that RV jitter tracks stellar evolution and that in general, stars evolve through different stages of RV jitter: the jitter in younger stars is driven by magnetic activity, while the jitter in older stars is convectively driven and dominated by granulation and oscillations. We identify the "jitter minimum"-where activity-driven and convectively driven jitter have similar amplitudes-for stars between 0.7 and 1.7M{sun} and find that more-massive stars reach this jitter minimum later in their lifetime, in the subgiant or even giant phases. Finally, we comment on how these results can inform future RV efforts, from prioritization of follow-up targets from transit surveys like the Transiting Exoplanet Survey Satellite (TESS) to target selection of future RV surveys.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/27
- Title:
- Radial velocity measurements in LAMOST-II
- Short Name:
- J/ApJS/244/27
- Date:
- 09 Dec 2021
- Publisher:
- CDS
- Description:
- The radial velocity (RV) is a basic physical quantity that can be determined through the Doppler shift of the spectrum of a star. The precision of the RV measurement depends on the resolution of the spectrum we used and the accuracy of wavelength calibration. In this work, radial velocities of the Large Sky Area Multi-Object Fibre Spectroscopic Telescope-II (LAMOST-II) medium-resolution (R~7500) spectra are measured for 1,594,956 spectra (each spectrum has two wavebands) through matching with templates. A set of RV standard stars are used to recalibrate the zero point of the measurement, and some reference sets with RVs derived from medium-/high-resolution observations are used to evaluate the accuracy of the measurement. By comparing with reference sets, the accuracy of our measurement can get 0.0277km/s with respect to radial velocities of standard stars. The intrinsic precision is estimated with the multiple observations of single stars, which can be achieved to 1.36km/s, 1.08km/s, and 0.91km/s for the spectra at signal-to-noise levels of 10, 20, and 50, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A159
- Title:
- Radial velocity measurements of 51 Peg
- Short Name:
- J/A+A/646/A159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of exoplanetary atmospheres by means of high-resolution spectroscopy is an expanding research field which provides information o n chemical composition, thermal structure, atmospheric dynamics and orbital velocity of exoplanets. In this work, we aim at the detection of the light reflected by the exoplanet 51 Peg b employing optical high-resolution spectroscopy. To detect the light reflected by the planetary dayside we use optical HARPS and HARPS-N spectra taken near the superior conjunction of the planet, when the flux contrast between the planet and the star is maximum. To search for the weak planetary signal, we cross-correlate the observed spectra with a high S/N stellar spectrum. We homogeneously analyze the available datasets and derive a 10^-5^ upper limit on the planet-to-star flux contrast in the optical. The upper limit on the planet-to-star flux contrast of 10^-5^ translates into a low albedo of the planetary atmosphere (A_g_~0.05-0.15 for an assumed planetary radius in the range 1.5-0.9R_Jup_, as estimated from the planet's mass).
- ID:
- ivo://CDS.VizieR/J/AJ/160/114
- Title:
- Radial velocity monitoring of TOI-421
- Short Name:
- J/AJ/160/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-141137, TIC94986319), a bright (V=9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421b, has an orbital period of Pb=5.19672{+/-}0.00049days, a mass of Mb=7.17{+/-}0.66M{Earth}, and a radius of Rb=2.68_-0.18_^+0.19^R{Earth}, whereas the outer warm Neptune, TOI-421c, has a period of Pc=16.06819{+/-}0.00035days, a mass of Mc=16.42_-1.04_^+1.06^M{Earth}, a radius of Rc=5.09_-0.15_^+0.16^R{Earth}, and a density of {rho}c=0.685_-0.072_^+0.080^g/cm^3^. With its characteristics, the outer planet ({rho}c=0.685_-0.072_^+0.080^g/cm^3^) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421b and TOI-421c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly{alpha} transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421c if equilibrium chemistry is assumed.
