scholarly journals Two Giant Planets Orbiting the K Giant Star η Cet

2013 ◽  
Vol 8 (S299) ◽  
pp. 309-310
Author(s):  
T. Trifonov ◽  
S. Reffert ◽  
X. Tan ◽  
M. H. Lee ◽  
A. Quirrenbach
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Parameter Space ◽  
Planetary System ◽  
Giant Planets ◽  
Stable Region ◽  
Velocity Data ◽  
Giant Star ◽  
Present Evidence ◽  
Radial Velocity Data

AbstractWe present evidence of a new planetary system around the K giant η Cet (HIP 5364, HD 6805, HR 334), based on 124 high-precision optical and infrared radial velocity data, taken at Lick Observatory (Hamilton) and at VLT (CRIRES). The best dynamical fit to the data is consistent with two massive planets (m1sini≈2.6MJup, m2sini≈3.3MJup) and with periods of P1≈407 days, P2≈740 days. To test the η Cet system's stability we perform ~ 10,000 dynamical investigations with maximum time spans of 108 years. We find that in case of moderate eccentricities, the planets can be effectively trapped in an anti-aligned stable 2:1 mean motion resonance (MMR), very close to the separatrix. A larger non-resonant stable region exists in low-eccentricity parameter space, although less probable than the 2:1 MMR region.

scholarly journals Revisiting theKeplerfield withTESS: Improved ephemerides usingTESS2 min data

2021 ◽  
Vol 503 (3) ◽  
pp. 4092-4104
Author(s):  
Matthew P Battley ◽  
Michelle Kunimoto ◽  
David J Armstrong ◽  
Don Pollacco
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Photometric Method ◽  
Velocity Data ◽  
Signal To Noise ◽  
Data Set ◽  
The Future ◽  
Radial Velocity Data ◽  
Very High

ABSTRACTUp to date planet ephemerides are becoming increasingly important as exoplanet science moves from detecting exoplanets to characterizing their architectures and atmospheres in depth. In this work, ephemerides are updated for 22 Kepler planets and 4 Kepler planet candidates, constituting all Kepler planets and candidates with sufficient signal to noise in the TESS 2 min data set. A purely photometric method is utilized here to allow ephemeris updates for planets even when they do not posses significant radial velocity data. The obtained ephemerides are of very high precision and at least seven years ‘fresher’ than archival ephemerides. In particular, significantly reduced period uncertainties for Kepler-411d, Kepler-538b, and the candidates K00075.01/K00076.01 are reported. O–C diagrams were generated for all objects, with the most interesting ones discussed here. Updated TTV fits of five known multiplanet systems with significant TTVs were also attempted (Kepler-18, Kepler-25, Kepler-51, Kepler-89, and Kepler-396), however these suffered from the comparative scarcity and dimness of these systems in TESS. Despite these difficulties, TESS has once again shown itself to be an incredibly powerful follow-up instrument as well as a planet-finder in its own right. Extension of the methods used in this paper to the 30 min-cadence TESS data and TESS extended mission has the potential to yield updated ephemerides of hundreds more systems in the future.

scholarly journals Detection of the nearest Jupiter analogue in radial velocity and astrometry data

2019 ◽  
Vol 490 (4) ◽  
pp. 5002-5016 ◽  
Author(s):  
Fabo Feng ◽  
Guillem Anglada-Escudé ◽  
Mikko Tuomi ◽  
Hugh R A Jones ◽  
Julio Chanamé ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Giant Planets ◽  
Velocity Data ◽  
Eccentric Orbit ◽  
Brown Dwarf ◽  
Nearby Star ◽  
Long Period ◽  
The Difference ◽  
Astrometric Data ◽  
Radial Velocity Data

ABSTRACT The presence of Jupiter is crucial to the architecture of the Solar system and models underline this to be a generic feature of planetary systems. We find the detection of the difference between the position and motion recorded by the contemporary astrometric satellite Gaia and its precursor Hipparcos can be used to discover Jupiter-like planets. We illustrate how observations of the nearby star ϵ Indi A giving astrometric and radial velocity data can be used to independently find the orbit of its suspected companion. The radial velocity and astrometric data provide complementary detections which allow for a much stronger solution than either technique would provide individually. We quantify ϵ Indi A b as the closest Jupiter-like exoplanet with a mass of 3 MJup on a slightly eccentric orbit with an orbital period of 45 yr. While other long-period exoplanets have been discovered, ϵ Indi A b provides a well-constrained mass and along with the well-studied brown dwarf binary in orbit around ϵ Indi A means that the system provides a benchmark case for our understanding of the formation of gas giant planets and brown dwarfs.

scholarly journals CHARACTERIZING THE ORBITAL AND DYNAMICAL STATE OF THE HD 82943 PLANETARY SYSTEM WITH KECK RADIAL VELOCITY DATA

2013 ◽  
Vol 777 (2) ◽  
pp. 101 ◽  
Author(s):  
Xianyu Tan ◽  
Matthew J. Payne ◽  
Man Hoi Lee ◽  
Eric B. Ford ◽  
Andrew W. Howard ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Planetary System ◽  
Velocity Data ◽  
Dynamical State ◽  
Radial Velocity Data

scholarly journals Chemical abundances of three new Ba stars from the Keck/HIRES spectra

2021 ◽  
Vol 21 (11) ◽  
pp. 278
Author(s):  
Shuai Liu ◽  
Liang Wang ◽  
Jian-Rong Shi ◽  
Zhen-Yu Wu ◽  
Hong-Liang Yan ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Parameter Space ◽  
Thin Disk ◽  
High Signal ◽  
Velocity Data ◽  
Signal To Noise ◽  
Chemical Abundances ◽  
Radial Velocity Data

Abstract Based on high resolution, high signal-to-noise (S/N) ratio spectra from Keck/HIRES, we have determined abundances of 20 elements for 18 Ba candidates. The parameter space of these stars is in the range of 4880 ≤ T eff ≤ 6050 K, 2.56 ≤ log g ≤ 4.53 dex and − 0.27 ≤ [Fe/H] ≤ 0.09 dex. It is found that four of them can be identified as Ba stars with [s/Fe] > 0.25 dex (s: Sr, Y, Zr, Ba, La, Ce and Nd), and three of them are newly discovered, which include two Ba giants (HD 16178 and HD 22233) and one Ba subgiant (HD 2946). Our results show that the abundances of α, odd and iron-peak elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, Mn, Ni and Cu) for our program stars are similar to those of the thin disk, while the distribution of [hs/ls] (hs: Ba, La, Ce and Nd, ls: Sr, Y and Zr) ratios of our Ba stars is similar to those of the known Ba objects. None of the four Ba stars show clear enhancement in carbon including the known CH subgiant HD 4395. It is found that three of the Ba stars present clear evidence of hosting stellar or sub-stellar companions from the radial velocity data.

scholarly journals Kinematics of Disk Stars in the Solar Neighbourhood

1998 ◽  
Vol 11 (1) ◽  
pp. 574-574
Author(s):  
A.E. Gómez ◽  
S. Grenier ◽  
S. Udry ◽  
M. Haywood ◽  
V. Sabas ◽  
...  
Keyword(s):  
Dispersion Relation ◽  
Radial Velocity ◽  
Velocity Dispersion ◽  
Tangential Velocity ◽  
Thin Disk ◽  
The Other ◽  
Proper Motions ◽  
Velocity Data ◽  
Kinematic Data ◽  
Radial Velocity Data

Using Hipparcos parallaxes and proper motions together with radial velocity data and individual ages estimated from isochones, the velocity ellipsoid has been determined as a function of age. On the basis of the available kinematic data two different samples were considered: a first one (7789 stars) for which only tangential velocities were calculated and a second one containing 3104 stars with available U, V and W velocity components and total velocities ≤ 65 km.s-1. The main conclusions are: -Mixing is not complete at about 0.8-1 Gyr. -The shape of the velocity ellipsoid changes with time getting rounder from σu/σv/σ-w = 1/0.63/0.42 ± 0.04 at about 1 Gyr to1/0.7/0.62 ±0.04 at 4-5 Gyr. -The age-velocity-dispersion relation (from the sample with kinematical selection) rises to a maximum, thereafter remaining roughly constant; there is no dynamically significant evolution of the disk after about 4-5 Gyr. -Among the stars with solar metallicities and log(age) > 9.8 two groups are identified: one has typical thin disk characteristics, the other is older than 10 Gyr and lags the LSR at about 40 km.s-1 . -The variation of the tangential velocity with age(without selection on the tangential velocity) shows a discontinuity at about 10 Gyr, which may be attributed to stars typically of the thick disk populations for ages > 10 Gyr.

An Efficient Dual-Resolution Approach for Ensemble Data Assimilation and Tests with Simulated Doppler Radar Data

2008 ◽  
Vol 136 (3) ◽  
pp. 945-963 ◽  
Author(s):  
Jidong Gao ◽  
Ming Xue
Keyword(s):  
High Resolution ◽  
Data Assimilation ◽  
Radial Velocity ◽  
Computational Cost ◽  
Radar Data ◽  
Horizontal Resolution ◽  
Velocity Data ◽  
Background Error ◽  
Cross Covariance ◽  
Radial Velocity Data

Abstract A new efficient dual-resolution (DR) data assimilation algorithm is developed based on the ensemble Kalman filter (EnKF) method and tested using simulated radar radial velocity data for a supercell storm. Radar observations are assimilated on both high-resolution and lower-resolution grids using the EnKF algorithm with flow-dependent background error covariances estimated from the lower-resolution ensemble. It is shown that the flow-dependent and dynamically evolved background error covariances thus estimated are effective in producing quality analyses on the high-resolution grid. The DR method has the advantage of being able to significantly reduce the computational cost of the EnKF analysis. In the system, the lower-resolution ensemble provides the flow-dependent background error covariance, while the single-high-resolution forecast and analysis provides the benefit of higher resolution, which is important for resolving the internal structures of thunderstorms. The relative smoothness of the covariance obtained from the lower 4-km-resolution ensemble does not appear to significantly degrade the quality of analysis. This is because the cross covariance among different variables is of first-order importance for “retrieving” unobserved variables from the radar radial velocity data. For the DR analysis, an ensemble size of 40 appears to be a reasonable choice with the use of a 4-km horizontal resolution in the ensemble and a 1-km resolution in the high-resolution analysis. Several sensitivity tests show that the DR EnKF system is quite robust to different observation errors. A 4-km thinned data resolution is a compromise that is acceptable under the constraint of real-time applications. A data density of 8 km leads to a significant degradation in the analysis.

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