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2111. Radial Velocity and BIS measurements of Polaris
ID:
ivo://CDS.VizieR/J/A+A/623/A146
Title:
Radial Velocity and BIS measurements of Polaris
Short Name:
J/A+A/623/A146
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate temporally changing variability amplitudes and the multi- periodicity of the type-I Cepheid Polaris using 162 high-precision radial velocity (RV) and bisector inverse span (BIS) measurements based on optical spectra recorded using Hermes at the 1.2m Flemish Mercator telescope on La Palma, Canary Islands, Spain. Using an empirical template fitting method, we show that Polaris' RV amplitude has been stable to within ~30m/s between September 2011 and November 2018. We apply the template fitting method to publicly accessible, homogeneous RV data sets from the literature and provide an updated solution of Polaris' eccentric 29.3yr orbit. While the inferred pulsation-induced RV amplitudes differ among individual data sets, we find no evidence for time-variable RV amplitudes in any of the separately considered, homogeneous data sets. Additionally, we find that increasing photometric amplitudes determined using SMEI photometry are likely spurious detections due to as yet ill-understood systematic effects of instrumental origin. Given this confusing situation, further analysis of high-quality homogeneous data sets with well-understood systematics is required to confidently establish whether Polaris' variability amplitude is subject to change over time. We confirm periodic bisector variability periods of 3.97d and 40.22d using Hermes BIS measurements and identify a third signal at a period of 60.17d. Although the 60.17d signal dominates the BIS periodogram, we caution that this signal may not be independent of the 40.22d signal. Finally, we show that the 40.22d signal cannot be explained by stellar rotation. Further long-term, high-quality spectroscopic monitoring is required to unravel the complete set of Polaris' periodic signals, which has the potential to provide unprecedented insights into the evolution of Cepheid variables.
2112. Radial velocity and g-i color in M85 globular clusters
ID:
ivo://CDS.VizieR/J/ApJ/903/110
Title:
Radial velocity and g-i color in M85 globular clusters
Short Name:
J/ApJ/903/110
Date:
15 Mar 2022
Publisher:
CDS
Description:
We present a study on the stellar population and kinematics of globular clusters (GCs) in the peculiar galaxy M85. We obtain optical spectra of 89 GCs at 8kpc<R<160kpc using the MMT/Hectospec. We divide them into three groups, blue/green/red GCs (B/G/RGCs), with their (g-i)0 colors. All GC subpopulations have mean ages of about 10Gyr, but showing differences in metallicities. The BGCs and RGCs are the most metal-poor ([Z/H]~-1.49) and metal-rich ([Z/H]~-0.45), respectively, and the GGCs are in between. We find that the inner GC system exhibits a strong overall rotation that is entirely due to a disklike rotation of the RGC system. The BGC system shows little rotation. The GGCs show kinematic properties clearly distinct among the GC subpopulations, having higher mean velocities than the BGCs and RGCs and being aligned along the major axis of M85. This implies that the GGCs have an origin different from the other GC subpopulations. The rotation-corrected velocity dispersion of the RGC system is much lower than that of the BGC system, indicating the truncation of the red halo of M85. The BGCs have a flat velocity dispersion profile out to R=67kpc, reflecting the dark matter extent of M85. Using the velocity dispersion of the BGC system, we estimate the dynamical mass of M85 to be 3.8x1012M{sun}. We infer that M85 has undergone merging events lately, resulting in the peculiar kinematics of the GC system.
2113. Radial Velocity and Photometry of HD 104994
ID:
ivo://CDS.VizieR/J/AJ/120/2101
Title:
Radial Velocity and Photometry of HD 104994
Short Name:
J/AJ/120/2101
Date:
21 Oct 2021
Publisher:
CDS
Description:
Intense coordinated spectroscopic and photometric monitoring of the suspected Wolf-Rayet binary WR 46 in 1999 reveals clear periodic variations, P=0.329+/-0.013 days, in the radial velocities of the emission lines of highest ionization potential, O VI and N V, found deepest in the Wolf-Rayet wind and thus least likely to be perturbed by a companion. These are accompanied by coherent variability in the profiles of lines with lower ionization/excitation potential and in the continuum flux. Most probably originating from orbital motion of the Wolf-Rayet component of the binary, this periodic radial velocity signal disappears from time to time, thus creating a puzzle yet to be solved. We show that the entangled patterns of the line profile variability are mainly governed by transitions between high and low states of the system's continuum flux. Based in part on observations obtained at the European Southern Observatory, La Silla, Chile (ESO program 62.H-0110).
2114. Radial velocity data of Kepler-432
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.
2115. Radial velocity estimates of 4 stars with IGRINS
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.
2116. Radial velocity exploration of {epsilon} Eridani
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.
2117. Radial velocity follow up of Barnard's star with HPF
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.
2118. Radial velocity follow-up of the HD 3167 system
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.
2119. Radial velocity for 19 RR Lyrae
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.
2120. Radial Velocity jitters in ~600 planet host stars
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.

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