- ID:
- ivo://CDS.VizieR/J/A+A/647/A160
- Title:
- Radial velocity data of epsilon Cyg
- Short Name:
- J/A+A/647/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Hamilton Echelle Spectrograph at Lick Observatory, we have obtained precise radial velocities of a sample of 373 G- and K-giant stars from 1999 until 2012, leading to the discovery of several single and multiple planetary systems. The radial velocities of the long-period (~53 years) spectroscopic binary epsilon Cyg (HIP 102488) are found to exhibit additional variations with a much shorter period (~291 days). This signature is not perfectly regular, as its period and amplitude seem to change over time. We intend to improve the orbital solution of the epsilon Cyg system, and attempt to identify the cause of the nearly periodic shorter period variations, which might be due to an additional substellar companion. We use precise radial velocity measurements of the K-giant star epsilon Cyg from Lick Observatory, in combination with a large set of RVs collected more recently with the SONG telescope, as well as archival data sets.
Number of results to display per page
Search Results
- 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/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/A+A/625/A71
- Title:
- Radial velocity measurements for 7 stars
- Short Name:
- J/A+A/625/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since 1998, a planet-search around main sequence stars within 50pc in the southern hemisphere has been underway with the CORALIE spectrograph at La Silla Observatory. With an observing time span of more than 20 years, the CORALIE survey is able to detect long-term trends in data with masses and separations large enough to select ideal targets for direct imaging. Detecting these giant companion candidates will allow us to start bridging the gap between radial-velocity-detected exoplanets and directly imaged planets and brown dwarfs. Long-term precise Doppler measurements with the CORALIE spectrograph reveal radial-velocity signatures of massive planetary companions and brown dwarfs on long-period orbits. In this paper we report the discovery of new companions orbiting HD 181234, HD 13724, HD 25015, HD 92987 and HD 50499. We also report updated orbital parameters for HD 50499b, HD 92788b and HD 98649b. In addition, we confirm the recent detection of HD 92788c. The newly reported companions span a period range of 15.6 to 40.4 years and a mass domain of 2.93 to 26.77 MJup, the latter of which straddles the nominal boundary between planets and brown dwarfs. We report the detection of five new companions and updated parameters of four known extrasolar planets. We identify at least some of these companions to be promising candidates for imaging and further characterisation.
- ID:
- ivo://CDS.VizieR/J/AJ/157/97
- Title:
- Radial velocity measurements of K2-3 & GJ3470
- Short Name:
- J/AJ/157/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations refined the transit ephemerides of K2-3 b, c, and d by over a factor of 10. We analyze ground-based photometry from the Evryscope and Fairborn Observatory to determine the characteristic stellar activity timescales for our Gaussian Process fit, including the stellar rotation period and activity region decay timescale. The stellar rotation signals for both stars are evident in the radial velocity data and is included in our fit using a Gaussian process trained on the photometry. We find the masses of K2-3 b, K2-3 c, and GJ3470 b to be 6.48_-0.93_^+0.99^, 2.14_-1.04_^+1.08^, and 12.58_-1.28_^+1.31^ M_{Earth}_, respectively. K2-3 d was not significantly detected and has a 3{sigma} upper limit of 2.80 M_{Earth}_. These two systems are training cases for future TESS systems; due to the low planet densities ({rho}<3.7 g/cm^-3^) and bright host stars (K<9 mag), they are among the best candidates for transmission spectroscopy in order to characterize the atmospheric compositions of small planets.
- 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.
