ORBITAL MOTION OF HR 8799 b, c, d USING HUBBLE SPACE TELESCOPE DATA FROM 1998: CONSTRAINTS ON INCLINATION, ECCENTRICITY, AND STABILITY

By V. Abramenko, V. Carbone, V. Yurchyshyn, P. Goode, R. F. Stein, F. Lepreti, V. Capparelli, A. Vecchio. 2011

168 citations recorded by the source corpus.

HR 8799 is currently the only multiple-planet system that has been detected with direct imaging, with four giant planets of masses 7–10 MJup orbiting at large separations (15–68 AU) from this young late A star. Orbital motion provides insight into the stability and possible formation mechanisms of this planetary system. Dynamical studies can also provide constraints on the planets’ masses, which help calibrate evolutionary models, yet measuring the orbital motion is a very difficult task because the long-period orbits (50–500 yr) require long time baselines and high-precision astrometry. This paper studies the three planets HR 8799b, c, and d in the archival data set of HR 8799 obtained with the Hubble Space Telescope (HST) NICMOS coronagraph in 1998. The detection of all three planets is made possible by a careful optimization of the Locally Optimized Combination of Images algorithm, and we used a statistical analysis of a large number of reduced images. This work confirms previous astrometry for planet b and presents new detections and astrometry for planets c and d. These HST images provide a ten-year baseline with the discovery images from 2008, and therefore offer a unique opportunity to constrain their orbital motion now. Recent dynamical studies of this system show the existence of a few possible stable solutions involving mean motion resonances (MMRs), where the interaction between c and d plays a major role. We study the compatibility of a few of these stable scenarios (1d:1c, 1d:2c, or 1d:2c:4d) with the new astrometric data from HST. In the hypothesis of a 1d:2c:4b MMR our best orbit fit is close to the stable solution previously identified for a three-planet system and involves low eccentricity for planet d (ed = 0.10) and moderate inclination of the system (i = 28.0 deg), assuming a coplanar system, circular orbits for b and c, and exact resonance with integer period ratios. Under these assumptions, we can place strong constraints on the inclination of the system (27.3–31.4 deg) and on the eccentricity for d ed < 0.46. Our results are robust to small departures from exact integer period ratios and consistent with previously published results based on dynamical studies for a three-planet system prior to the discovery of the fourth planet.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/21bf7a771b13b75ca69937743a84f14a1ee5a23a

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Citations in the corpus

• DIRECT IMAGING OF A COLD JOVIAN EXOPLANET IN ORBIT AROUND THE SUN-LIKE STAR GJ 504 (2013, background): “Sometimes, LOCI introduces artificial shifts of the companion positions (Soummer et al. 2011).”
• Dawes Review 6: The Impact of Companions on Stellar Evolution (2016, background): “Imaging surveys able to detect high contrast are few and have detected only a handful of planets out to tens of AU (Soummer et al., 2011; Kuzuhara et al., 2013).”
• DISCOVERY AND VALIDATION OF Kepler-452b: A 1.6 R⨁ SUPER EARTH EXOPLANET IN THE HABITABLE ZONE OF A G2 STAR (2015, background): “…through a variety of means, including Doppler surveys, ground- and space-based transit surveys, gravitational microlensing surveys (starting in 1996 with OGLE-2003-BLG-235/MOA-2003-BLG-53, Bennett et al. 2006), and recently, direct imaging (beginning in 2011 with HR 8799, Soummer et al. 2011).”
• DETECTION AND CHARACTERIZATION OF EXOPLANETS AND DISKS USING PROJECTIONS ON KARHUNEN–LOÈVE EIGENIMAGES (2012, methodology): “Biases can be reduced significantly using statistical exploration of the algorithm parameter space (Soummer et al. 2011a), a computationally expensive solution, or by modifying the underlying cost function by masking some pixels (Marois et al. 2010a) or using damping penalty terms (Pueyo et al.…”
• PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, methodology): “…Ford 2002; Marois et al. 2005; Thatte et al. 2007; Biller et al. 2008; Crepp et al. 2011) together with more sophisticated processing techniques (Lafrenière et al. 2007b; Marois et al. 2010a; Soummer et al. 2011; Pueyo et al. 2012) are yielding contrasts >14 mag at 1′′ (e.g., Wahhaj et al. 2013b).”
• REGULARITY UNDERLYING COMPLEXITY: A REDSHIFT-INDEPENDENT DESCRIPTION OF THE CONTINUOUS VARIATION OF GALAXY-SCALE MOLECULAR GAS PROPERTIES IN THE MASS-STAR FORMATION RATE PLANE (2013, unknown): “…evidence for constancy (e.g., Dessauges-Zavadsky et al. 2011, Richard et al. 2011, Lara-López et al. 2013, Belli et al. 2013) and evolution (e.g., Laskar et al. 2011, Sommariva et al. 2012) of the FMR has been presented. metallicities (see, e.g., Bolatto et al. 2013; and references therein).”
• MASSES, RADII, AND CLOUD PROPERTIES OF THE HR 8799 PLANETS (2012, background): “HR 8799 b, c, and d have also been identified in an archived Hubble Space Telescope image taken in 1998 (Lafrenière et al. 2009; Soummer et al. 2011).”