The GJ 504 system revisited: Combining interferometric, radial velocity, and high contrast imaging data

The G-type star GJ504A is known to host a 3 to 35 MJup companion whose temperature, mass, and projected separation all contribute to make it a test case for the planet formation theories and for atmospheric models of giant planets and light brown dwarfs. We collected data from the CHARA interferometer, SOPHIE spectrograph, and VLT/SPHERE high contrast imager to revisit the properties of the system. We measure a radius of 1.35+/- 0.04Rsun for GJ504A which yields isochronal ages of 21+/-2Myr or 4.0+/-1.8Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4+3.8−4.3 degrees or 18.6+4.3−3.8 degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual band SPHERE 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 six atmospheric models used yield Teff=550±50K 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 logL/L⊙=−6.15±0.15 dex for the companion compatible with masses of M=1.3+0.6−0.3MJup and M=23+10−9MJup for the young and old age ranges, respectively. The semi-major axis (sma) is above 27.8 au and the eccentricity lower than 0.55. The posterior on GJ~504b's orbital inclination suggests a misalignment with GJ~504A rotation axis. We combine the radial velocity and multi-epoch imaging data to exclude additional objects (90\% prob.) more massive than 2.5 and 30 MJup with sma in the range 0.01-80 au for the young and old system ages, respectively. The companion is in the envelope of the population of planets synthetized with our core-accretion model

The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data

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. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 093.C-0500, 095.C-0298, 096.C-0241, and 198.C-0209, and on interferometric observations obtained with the VEGA instrument on the CHARA Array

The GJ 504 system revisited

International audienceContext. The G-type star GJ504A is known to host a 3–35 M Jup 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 H IPPARCOS 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 μ m) 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 μ m 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 T eff = 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 T eff yield masses of M = 1.3 −0.3 +0.6 M Jup and M = 23 −9 +10 M Jup 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 M Jup 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

The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data

Context The G-type star GJ504A is known to host a 3 to 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 combination with 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 NIR (1.02-2.25μm) 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’s orbital 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+3.8/−4.3 degrees or 18.6+4.3/−3.8 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 ± 50K 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+0.6 −0.3MJup and M = 23+10 −9 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.</p

The GJ 504 system revisited

International audienceContext. The G-type star GJ504A is known to host a 3–35 M Jup 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 H IPPARCOS 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 μ m) 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 μ m 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 T eff = 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 T eff yield masses of M = 1.3 −0.3 +0.6 M Jup and M = 23 −9 +10 M Jup 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 M Jup 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

The GJ 504 system revisited

International audienceContext. The G-type star GJ504A is known to host a 3–35 M Jup 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 H IPPARCOS 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 μ m) 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 μ m 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 T eff = 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 T eff yield masses of M = 1.3 −0.3 +0.6 M Jup and M = 23 −9 +10 M Jup 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 M Jup 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

The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data

International audienceContext. The G-type star GJ504A is known to host a 3-35 M&lt;SUB&gt;Jup&lt;/SUB&gt; 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. &lt;BR /&gt; 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. &lt;BR /&gt; 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 mum) 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. &lt;BR /&gt; Results: We report a radius of 1.35 &plusmn; 0.04 R&lt;SUB&gt;&amp;sun;&lt;/SUB&gt; for GJ504A. The radius yields isochronal ages of 21 &plusmn; 2 Myr or 4.0 &plusmn; 1.8 Gyr for the system and line-of-sight stellar rotation axis inclination of 162.4&lt;SUB&gt;-4.3&lt;/SUB&gt;&lt;SUP&gt; 3.8&lt;/SUP&gt; degrees or 186.6&lt;SUB&gt;-3.8&lt;/SUB&gt;&lt;SUP&gt; 4.3&lt;/SUP&gt; degrees. We re-detect the companion in the Y2, Y3, J3, H2, and K1 dual-band images. The complete 1-4 mum SED shape of GJ504b is best reproduced by T8-T9.5 objects with intermediate ages (&lt;= 1.5Gyr), and/or unusual dusty atmospheres and/or super-solar metallicities. All atmospheric models yield T&lt;SUB&gt;eff&lt;/SUB&gt; = 550 &plusmn; 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&lt;SUB&gt;&amp;sun;&lt;/SUB&gt; = -6.15 &plusmn; 0.15 dex for the companion from the empirical analysis and spectral synthesis. The luminosity and T&lt;SUB&gt;eff&lt;/SUB&gt; yield masses of M = 1.3&lt;SUB&gt;-0.3&lt;/SUB&gt;&lt;SUP&gt; 0.6&lt;/SUP&gt; M&lt;SUB&gt;Jup&lt;/SUB&gt; and M = 23&lt;SUB&gt;-9&lt;/SUB&gt;&lt;SUP&gt; 10&lt;/SUP&gt; M&lt;SUB&gt;Jup&lt;/SUB&gt; 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 M&lt;SUB&gt;Jup&lt;/SUB&gt; with semi-major axes in the range 0.01-80 au for the young and old isochronal ages, respectively. &lt;BR /&gt; 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