scholarly journals The GJ 504 system revisited

2018 ◽  
Vol 618 ◽  
pp. A63 ◽  
Author(s):  
M. Bonnefoy ◽  
K. Perraut ◽  
A.-M. Lagrange ◽  
P. Delorme ◽  
A. Vigan ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Rotation Axis ◽  
Spectral Synthesis ◽  
Spectral Energy Distribution ◽  
Major Axis ◽  
Dual Band ◽  
Imaging Data ◽  
Atmospheric Models ◽  
Semi Major Axis ◽  
Orbital Inclination

Context. The G-type star GJ504A is known to host a 3–35 MJup companion whose temperature, mass, and projected separation all contribute to making it a test case for planet formation theories and atmospheric models of giant planets and light brown dwarfs. Aims. We aim at revisiting the system age, architecture, and companion physical and chemical properties using new complementary interferometric, radial-velocity, and high-contrast imaging data. Methods. We used the CHARA interferometer to measure GJ504A’s angular diameter and obtained an estimation of its radius in combinationwith the HIPPARCOS parallax. The radius was compared to evolutionary tracks to infer a new independent age range for the system. We collected dual imaging data with IRDIS on VLT/SPHERE to sample the near-infrared (1.02–2.25 μm) spectral energy distribution (SED) of the companion. The SED was compared to five independent grids of atmospheric models (petitCODE,Exo-REM, BT-SETTL, Morley et al., and ATMO) to infer the atmospheric parameters of GJ 504b and evaluate model-to-model systematic errors. In addition, we used a specific model grid exploring the effect of different C/O ratios. Contrast limits from 2011 to 2017 were combined with radial velocity data of the host star through the MESS2 tool to define upper limits on the mass of additional companions in the system from 0.01 to 100 au. We used an MCMC fitting tool to constrain the companion’sorbital parameters based on the measured astrometry, and dedicated formation models to investigate its origin. Results. We report a radius of 1.35 ± 0.04 R⊙ for GJ504A. The radius yields isochronal ages of 21 ± 2 Myr or 4.0 ± 1.8 Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4−4.3+3.8 degrees or 186.6−3.8+4.3 degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual-band images. The complete 1–4 μm SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages (≤ 1.5Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All atmospheric models yield Teff = 550 ± 50 K for GJ504b and point toward a low surface gravity (3.5–4.0 dex). The accuracy on the metallicity value is limited by model-to-model systematics; it is not degenerate with the C/O ratio. We derive log L∕L⊙ = −6.15 ± 0.15 dex for the companion from the empirical analysis and spectral synthesis. The luminosity and Teff yield masses of M = 1.3−0.3+0.6 MJup and M = 23−9+10 MJup for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity is lower than 0.55. The posterior on GJ 504b’s orbital inclination suggests a misalignment with the rotation axis of GJ 504A. We exclude additional objects (90% prob.) more massive than 2.5 and 30 MJup with semi-major axes in the range 0.01–80 au for the young and old isochronal ages, respectively. Conclusions. The mass and semi-major axis of GJ 504b are marginally compatible with a formation by disk-instability if the system is 4 Gyr old. The companion is in the envelope of the population of planets synthesized with our core-accretion model. Additional deep imaging and spectroscopic data with SPHERE and JWST should help to confirm the possible spin-orbit misalignment and refine the estimates on the companion temperature, luminosity, and atmospheric composition.

scholarly journals Investigating the young solar system analog HD 95086

2018 ◽  
Vol 617 ◽  
pp. A76 ◽  
Author(s):  
G. Chauvin ◽  
R. Gratton ◽  
M. Bonnefoy ◽  
A.-M. Lagrange ◽  
J. de Boer ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Scattered Light ◽  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Giant Planets ◽  
Dual Band ◽  
Spectral Energy ◽  
Semi Major Axis ◽  
Integral Field Spectrograph

Context. HD 95086 (A8V, 17 Myr) hosts a rare planetary system for which a multi-belt debris disk and a giant planet of 4–5 MJup have been directly imaged. Aims. Our study aims to characterize the global architecture of this young system using the combination of radial velocity and direct imaging observations. We want to characterize the physical and orbital properties of HD 95086 b, search for additional planets at short and wide orbits and image the cold outer debris belt in scattered light. Methods. We used HARPS at the ESO 3.6 m telescope to monitor the radial velocity of HD 95086 over two years and investigate the existence of giant planets at less than 3 au orbital distance. With the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE at VLT, we imaged the faint circumstellar environment beyond 10 au at six epochs between 2015 and 2017. Results. We do not detect additional giant planets around HD 95086. We identify the nature (bound companion or background contaminant) of all point-like sources detected in the IRDIS field of view. None of them correspond to the ones recently discovered near the edge of the cold outer belt by ALMA. HD 95086 b is resolved for the first time in J-band with IFS. Its near-infrared spectral energy distribution is well fitted by a few dusty and/or young L7–L9 dwarf spectral templates. The extremely red 1–4 μm spectral distribution is typical of low-gravity objects at the L/T spectral type transition. The planet’s orbital motion is resolved between January 2015 and May 2017. Together with past NaCo measurements properly re-calibrated, our orbital fitting solutions favor a retrograde low to moderate-eccentricity orbit e = 0.2+0.3−0.2, with a semi-major axis ~52 au corresponding to orbital periods of ~288 yr and an inclination that peaks at i = 141°, which is compatible with a planet-disk coplanar configuration. Finally, we report the detection in polarimetric differential imaging of the cold outer debris belt between 100 and 300 au, consistent in radial extent with recent ALMA 1.3 mm resolved observations.

scholarly journals Properties of the young gas giant planet β Pictoris b

2013 ◽  
Vol 8 (S299) ◽  
pp. 241-246
Author(s):  
Mickaël Bonnefoy ◽  
Anthony Boccaletti ◽  
Anne-Marie Lagrange ◽  
France Allard ◽  
Christoph Mordasini ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Major Axis ◽  
Spectral Energy ◽  
Atmospheric Models ◽  
Semi Major Axis ◽  
Orbital Parameters ◽  
Formation History ◽  
History Of ◽  
Gas Giant

AbstractThe young (12+8−4 Myr) and nearby (19.44±0.05 pc) star β Pictoris is considered one of the best laboratories for the study of early phases of planetary systems formation since the identification of an extended debris disk surrounding the star in 1984. In 2009, we imaged at 3.8 μm with NaCo at VLT a gas giant planet around β Pictoris, roughly along the disk mid-plane, with a semi-major axis between 8 and 14 AU. We present here the first images of the planet in the J (1.265 μm), H (1.66 μm), and M' (4.78 μm) bands obtained between 2011 and 2012. We used these data to build the 1-5 μm spectral energy distribution (SED) of the companion, and to consolidate previous semi-major axis (8-10 AU) estimates. We compared the SED to seven atmospheric models to derive Teff = 1700 ± 100 K. We used the temperature and the luminosity of β Pictoris b to estimate new masses for the companion. We compared these masses to independent constraints set by the orbital parameters and the radial velocities and use them to discuss the formation history of the object.

scholarly journals γ DOR: A PULSATING COMPONENT OF KIC 8043961 IN A STELLAR TRIPLE SYSTEM

2020 ◽  
Vol 56 (2) ◽  
pp. 179-191
Author(s):  
C. Kamil ◽  
H. A. Dal ◽  
O. Özdarcan ◽  
E. Yoldaş
Keyword(s):  
Major Axis ◽  
Primary Component ◽  
Mass Ratio ◽  
Third Body ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
The Third ◽  
New Findings ◽  
Effective Temperatures ◽  
Orbit Model

We present new findings about KIC 8043961. We find the effective temperatures of the components as 6900 ± 200 K for the primary, and 6598 ± 200 K for the secondary, while the logarithm of the surface gravities are found to be 4.06 cm s-2 and 3.77 cm s-2, respectively. Combination of the light curve with the spectroscopic orbit model results leads to a mass ratio of 1.09 ± 0.07 with an orbital inclination of 73.71 ± 0.14 and a semi-major axis of 8.05 ± 0.22 R⨀ . Masses of the primary and secondary components are calculated as 1.379 ± 0.109 M⨀ and 1.513 ± 0.181 M⨀, while the radii are found to be 1.806 ± 0.084 R⨀ and 2.611 ± 0.059 R⨀. In addition, we obtain a considerable light contribution (≈0.54%) of a third body. We compute a possible mass for the third body as 0.778 ± 0.002 M⨀. We find that the primary component exhibits γ Dor type pulsations with 137 frequencies.

scholarly journals Hint of curvature in the orbital motion of the exoplanet 51 Eridani b using 3 yr of VLT/SPHERE monitoring

2019 ◽  
Vol 624 ◽  
pp. A118 ◽  
Author(s):  
A.-L. Maire ◽  
L. Rodet ◽  
F. Cantalloube ◽  
R. Galicher ◽  
W. Brandner ◽  
...  
Keyword(s):  
Orbital Motion ◽  
Rotation Axis ◽  
Spectral Energy Distribution ◽  
Giant Planet ◽  
Spectral Energy ◽  
Spin Orbit ◽  
Stellar Rotation ◽  
Semi Major Axis ◽  
Primary Star ◽  
Orbital Parameters

Context. The 51 Eridani system harbors a complex architecture with its primary star forming a hierarchical system with the binary GJ 3305AB at a projected separation of 2000 au, a giant planet orbiting the primary star at 13 au, and a low-mass debris disk around the primary star with possible cold and warm components inferred from the spectral energy distribution. Aims. We aim to better constrain the orbital parameters of the known giant planet. Methods. We monitored the system over three years from 2015 to 2018 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument at the Very Large Telescope (VLT). Results. We measure an orbital motion for the planet of ~130 mas with a slightly decreasing separation (~10 mas) and find a hint of curvature. This potential curvature is further supported at 3σ significance when including literature Gemini Planet Imager (GPI) astrometry corrected for calibration systematics. Fits of the SPHERE and GPI data using three complementary approaches provide broadly similar results. The data suggest an orbital period of 32−9+17 yr (i.e., 12−2+4 au in semi-major axis), an inclination of 133−7+14 deg, an eccentricity of 0.45−0.15+0.10, and an argument of periastron passage of 87−30+34 deg [mod 180°]. The time at periastron passage and the longitude of node exhibit bimodal distributions because we do not yet detect whether the planet is accelerating or decelerating along its orbit. Given the inclinations of the orbit and of the stellar rotation axis (134–144°), we infer alignment or misalignment within 18° for the star–planet spin-orbit. Further astrometric monitoring in the next 3–4 yr is required to confirm at a higher significance the curvature in the motion of the planet, determine if the planet is accelerating or decelerating on its orbit, and further constrain its orbital parameters and the star–planet spin-orbit.

scholarly journals Discovery of a brown dwarf companion to the star HIP 64892

2018 ◽  
Vol 615 ◽  
pp. A160 ◽  
Author(s):  
A. Cheetham ◽  
M. Bonnefoy ◽  
S. Desidera ◽  
M. Langlois ◽  
A. Vigan ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Angular Separation ◽  
Dual Band ◽  
Spectral Energy ◽  
Mass Ratio ◽  
Atmospheric Models ◽  
Brown Dwarf ◽  
Low Mass ◽  
Formation And Evolution ◽  
Projected Distance

We report the discovery of a bright, brown dwarf companion to the star HIP 64892, imaged with VLT/SPHERE during the SHINE exoplanet survey. The host is a B9.5V member of the Lower-Centaurus-Crux subgroup of the Scorpius Centaurus OB association. The measured angular separation of the companion (1.2705 ± 0.0023”) corresponds to a projected distance of 159 ± 12 AU. We observed the target with the dual-band imaging and long-slit spectroscopy modes of the IRDIS imager to obtain its spectral energy distribution (SED) and astrometry. In addition, we reprocessed archival NACO L-band data, from which we also recover the companion. Its SED is consistent with a young (<30 Myr), low surface gravity object with a spectral type of M9γ ± 1. From comparison with the BT-Settl atmospheric models we estimate an effective temperature of Teff = 2600 ± 100 K, and comparison of the companion photometry to the COND evolutionary models yields a mass of ~29−37 MJ at the estimated age of 16−7+15 Myr for the system. The star HIP 64892 is a rare example of an extreme-mass ratio system (q ~ 0.01) and will be useful for testing models relating to the formation and evolution of such low-mass objects.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 609 ◽  
pp. L5 ◽  
Author(s):  
A. Reiners ◽  
I. Ribas ◽  
M. Zechmeister ◽  
J. A. Caballero ◽  
T. Trifonov ◽  
...  
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Rotation Period ◽  
Major Axis ◽  
Temperate Zone ◽  
Minimum Mass ◽  
M Dwarfs ◽  
Semi Major Axis ◽  
Liquid Form

We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V = 8.9 mag, M = 0.58 ± 0.08 M⊙), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of K = 5.1 ± 0.4 m s−1 and a period of P = 86.54 ± 0.06 d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass mP sin i = 25 ± 2 M⊕, 1.5 times the mass of Neptune, with an orbital semi-major axis a = 0.32 au and low eccentricity (e < 0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1 d (and its first harmonic), which we attribute to the rotation period of the star.

Effect of an oblate rotating atmosphere on the orientation of a satellite orbit

1961 ◽  
Vol 261 (1305) ◽  
pp. 246-258 ◽  
Keyword(s):  
Orbital Plane ◽  
Satellite Orbit ◽  
Major Axis ◽  
Earth Satellite ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
Small Eccentricity ◽  
Earth Satellite Orbit ◽  
The Right ◽  
Right Ascension

For an earth satellite orbit of small eccentricity ( e < 0·2) formulae are derived for the changes per revolution produced by the atmosphere in the argument of perigee, in the right ascension of the ascending node, and in the orbital inclination. These changes are then expressed in terms of the change in length of the semi-major axis, and numerical values are obtained for satellite 1957 β . It is found that the rotation of the major axis in the orbital plane due to the atmosphere is significant, being most important for inclinations between 60 and 70°. The total rotation, due both to the gravitational potential and to the atmosphere, agrees reasonably well with the observed values. The oblateness of the atmosphere is found to have only a small effect on the changes in the orbital inclination and the right ascension of the ascending node.

A discussion on orbital analysis - Odd zonal harmonics in the geopotential, determined from fourteen well-distributed satellite orbits

1967 ◽  
Vol 262 (1124) ◽  
pp. 144-147
Keyword(s):  
Gravitational Potential ◽  
Major Axis ◽  
Detailed Account ◽  
Satellite Orbits ◽  
Orbital Eccentricity ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
Zonal Harmonics ◽  
Distributed Satellite ◽  
Orbital Analysis

Coefficients of the odd zonal harmonics in the Earth’s gravitational potential are evaluated by analysing the oscillations in orbital eccentricity of fourteen satellites chosen to give the widest and most uniform possible distribution in orbital inclination and semi-major axis. The best representations of the odd zonal harmonics are found to be in terms of seven coefficients (J5, */15)) or ten coefficients (J 3,J 5, J 21) and values for these coefficients are given. A detailed account of this work is being published in Planetary and Space Science.

scholarly journals Averaged changes in the orbital elements of meteoroids due to Yarkovsky-Radzievskij force

2014 ◽  
Vol 9 (S310) ◽  
pp. 160-161
Author(s):  
Galina O. Ryabova
Keyword(s):  
Rotation Axis ◽  
Major Axis ◽  
Orbital Elements ◽  
Meteoroid Stream ◽  
Semi Major Axis ◽  
Estimate Dispersion

AbstractYarkovsky-Radzievskij effect exceeds the Poynting-Robertson effect in the perturbing action on particles larger than 100 μm. We obtained formulae for averaged changes in a meteoroid's Keplerian orbital elements and used them to estimate dispersion in the Geminid meteoroid stream. It was found that dispersion in semi-major axis of the model shower increased nearly three times on condition that meteoroids rotation is fast, and the rotation axis is stable.

scholarly journals Imaging and Modeling of Double Stars with the Navy Prototype Optical Interferometer: a Continuation of the Mark III Double Star Program

1999 ◽  
Vol 170 ◽  
pp. 416-421
Author(s):  
Christian A. Hummel
Keyword(s):  
High Precision ◽  
Stellar System ◽  
Major Axis ◽  
Double Star ◽  
Physical Parameters ◽  
Optical Interferometer ◽  
Semi Major Axis ◽  
Orbital Inclination ◽  
Double Stars ◽  
Star Program

AbstractWe present results from the new Navy Prototype Optical Interferometer (NPOI) – the orbit of the double star Mizar A and measurements of Matar – which are compared to an orbit determined with the predecessor of NPOI, the Mark III Interferometer. Uncertainties of the orbital inclination are between 0.1 and 0.3 degrees; those of the semi-major axis are less than 0.5 percent. We determine the component masses and other parameters of the double star system, including relative photometry, directly through a fit to a combination of interferometric and spectroscopic data. Algorithms were developed to handle any hierarchical stellar system.We describe plans for the study of spectroscopic double stars with NPOI, which draw from our experience with the Mark III binary program. This program yielded orbits of 26 stars, of which 17 were published with mass determinations of 24 components using spectroscopy. The accuracy of the physical parameters were often limited by the spectroscopy. We show that in order to benefit from the high precision of the interferometric observations, new high-precision spectroscopic observations, combined with improved algorithms for the detection of the secondaries, are required.

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