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 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 Another Superdense Sub-Neptune in K2-182 b and Refined Mass Measurements for K2-199 b and c*

2021 ◽  
Vol 162 (6) ◽  
pp. 294
Author(s):  
Joseph M. Akana Murphy ◽  
Molly R. Kosiarek ◽  
Natalie M. Batalha ◽  
Erica J. Gonzales ◽  
Howard Isaacson ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Velocity Data ◽  
Velocity Measurements ◽  
Mass Measurements ◽  
Data Set ◽  
Valuable Data ◽  
Data Points ◽  
The Masses ◽  
Radial Velocity Data ◽  
Intermediate Density

Abstract We combine multiple campaigns of K2 photometry with precision radial velocity measurements from Keck-HIRES to measure the masses of three sub-Neptune-sized planets. We confirm the planetary nature of the massive sub-Neptune K2-182 b (P b = 4.7 days, R b = 2.69 R ⊕) and derive refined parameters for K2-199 b and c (P b = 3.2 days, R b = 1.73 R ⊕ and P c = 7.4 days, R c = 2.85 R ⊕). These planets provide valuable data points in the mass–radius plane, especially as TESS continues to reveal an increasingly diverse sample of sub-Neptunes. The moderately bright (V = 12.0 mag) early K dwarf K2-182 (EPIC 211359660) was observed during K2 campaigns 5 and 18. We find that K2-182 b is potentially one of the densest sub-Neptunes known to date (20 ± 5 M ⊕ and 5.6 ± 1.4 g cm−3). The K5V dwarf K2-199 (EPIC 212779596; V = 12.3 mag), observed in K2 campaigns 6 and 17, hosts two recently confirmed planets. We refine the orbital and planetary parameters for K2-199 b and c by modeling both campaigns of K2 photometry and adding 12 Keck-HIRES measurements to the existing radial velocity data set (N = 33). We find that K2-199 b is likely rocky, at 6.9 ± 1.8 M ⊕ and 7.2 − 2.0 + 2.1 g cm−3, and that K2-199 c has an intermediate density at 12.4 ± 2.3 M ⊕ and 2.9 − 0.6 + 0.7 g cm−3. We contextualize these planets on the mass–radius plane, discuss a small but intriguing population of “superdense” sub-Neptunes (R p < 3 R ⊕, M p >20 M ⊕), and consider our prospects for the planets’ atmospheric characterization.

scholarly journals DEMONEX: The DEdicated MONitor of EXotransits

2008 ◽  
Vol 4 (S253) ◽  
pp. 408-411 ◽  
Author(s):  
J. D. Eastman ◽  
B. S. Gaudi ◽  
D. L. DePoy
Keyword(s):  
Radial Velocity ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Signal To Noise ◽  
Data Set ◽  
Transiting Planets ◽  
Readout Time ◽  
Robotic Telescope ◽  
Homogeneous Data

AbstractDEMONEX is a low-cost, 0.5 meter, robotic telescope assembled mostly from commercially available parts dedicated to obtaining precise photometry of bright stars with transiting planets. This photometry will provide a homogeneous data set for all transits visible from its location at Winer Observatory in Sonoita, Arizona. We will also search for additional planets via transit timing variations, measure or place limits on the albedos from secondary eclipses, systematically search known radial velocity planets for those that transit, and follow up promising KELT candidates. Despite its modest size, the signal-to-noise ratio per transit is comparable to that obtained with larger, 1m-class telescopes because of its short readout time and high z-band quantum efficiency. However, its main strength is that it will be used every night for transit follow-up and gather an unprecedented data set on transiting planets. With the 24 known transiting planets and 112 radial velocity planets visible from Winer Observatory, over 90% of all nights have at least one full event to observe.

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.

scholarly journals Precipitation cloud identification based on faster-RCNN for Doppler weather radar

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Yuanbo Ran ◽  
Haijiang Wang ◽  
Li Tian ◽  
Jiang Wu ◽  
Xiaohong Li
Keyword(s):  
Radial Velocity ◽  
Vertical Direction ◽  
Weather Radar ◽  
Radar Reflectivity ◽  
Convective Precipitation ◽  
Horizontal Wind ◽  
Doppler Weather Radar ◽  
Velocity Data ◽  
Precipitation Processes ◽  
Radial Velocity Data

AbstractPrecipitation clouds are visible aggregates of hydrometeor in the air that floating in the atmosphere after condensation, which can be divided into stratiform cloud and convective cloud. Different precipitation clouds often accompany different precipitation processes. Accurate identification of precipitation clouds is significant for the prediction of severe precipitation processes. Traditional identification methods mostly depend on the differences of radar reflectivity distribution morphology between stratiform and convective precipitation clouds in three-dimensional space. However, all of them have a common shortcoming that the radial velocity data detected by Doppler Weather Radar has not been applied to the identification of precipitation clouds because it is insensitive to the convective movement in the vertical direction. This paper proposes a new method for precipitation clouds identification based on deep learning algorithm, which is according the distribution morphology of multiple radar data. It mainly includes three parts, which are Constant Altitude Plan Position Indicator data (CAPPI) interpolation for radar reflectivity, Radial projection of the ground horizontal wind field by using radial velocity data, and the precipitation clouds identification based on Faster-RCNN. The testing result shows that the method proposed in this paper performs better than the traditional methods in terms of precision. Moreover, this method boasts great advantages in running time and adaptive ability.

The CORAVEL Radial Velocity Data Base

2017 ◽  
Vol 13 (S334) ◽  
pp. 271-272
Author(s):  
Stéphane Udry ◽  
Maxime Marmier ◽  
Michel Mayor ◽  
Johannes Andersen ◽  
Birgitta Nordström
Keyword(s):  
Radial Velocity ◽  
Data Base ◽  
Radial Velocities ◽  
Velocity Data ◽  
Radial Velocity Data

AbstractFrom 1977 to 1999, thousands of accurate radial velocities in both hemispheres were made on a large variety of programmes with the two CORAVEL scanners. The data base of ~350000 individual observations will now be made available to complement the Gaia data.

scholarly journals The Radial Velocity Curve of V652 Her (BD+13°3224)

1985 ◽  
Vol 87 ◽  
pp. 109-115
Author(s):  
P.W. Hill ◽  
C.S. Jeffery
Keyword(s):  
Radial Velocity ◽  
Time Resolution ◽  
High Frequency ◽  
Velocity Curve ◽  
Velocity Data ◽  
Effective Surface ◽  
Radial Velocity Curve ◽  
Minimum Radius ◽  
Helium Star ◽  
Radial Velocity Data

AbstractNew radial velocity data for the pulsating extreme helium star V652 Her (BD+13°3224) have been obtained with a time resolution of 100 s. High frequency structure in the radial velocity curve is detected, and a comparison with previous data suggests that the detailed shape of the velocity curve is variable. The data imply that the effective surface gravity must increase by a factor of 4 at minimum radius.

Sign in / Sign up

Export Citation Format

Share Document