Observations in the past decade have revealed extrasolar planets with a wide range of orbital semimajor axes and eccentricities. Based on present understanding planet formation via core accretion oligarchic growth, we expect that giant often form closely packed configurations. While protoplanets are embedded protoplanetary gas disk, dissipation can prevent eccentricity growth suppress instabilities from becoming manifest. However, once disk dissipates, eccentricities grow rapidly, leading to...

We present new 1--1.25 micron (z and J band) Subaru/IRCS 2 (K VLT/NaCo data for HR 8799 a rereduction of the 3--5 MMT/Clio first presented by Hinz et al. (2010). Our yields detection fourth planet at projected separation ~ 15 AU -- "HR 8799e". also report new, albeit weak detections 8799b 1.03 microns 3.3 microns. Empirical comparisons to field brown dwarfs show that least HR8799c, possibly 8799d, have near-to-mid IR colors/magnitudes significantly discrepant from L/T dwarf sequence....

Recent discoveries of several transiting planets with clearly non-zero eccentricities and some large inclinations started changing the simple picture close-in having circular well-aligned orbits. Two major scenarios to form such are planet migration in a disk, planet--planet interactions combined tidal dissipation. The former scenario can naturally produce low-obliquity orbit, while latter implicitly assumes an initially highly eccentric possibly high-obliquity which then circularized...

The ensemble of now more than 250 discovered planetary systems displays a wide range masses, orbits and, in multiple systems, dynamical interactions. These represent the end point complex sequence events, wherein an entire protostellar disk converts itself into small number bodies. Here, we present self-consistent numerical simulations this process, which produce results agreement with some key trends observed properties exoplanets. Analogs to our own solar system do not appear be common,...

We present Subaru/IRCS J-band data for Fomalhaut and a (re)reduction of archival 2004–2006 HST/ACS first presented by Kalas et al. confirm the existence candidate exoplanet, b, in both 2004 2006 F606W sets at high signal-to-noise ratio. Additionally, we detection F814W new F435W. b's space motion may be consistent with it being an apsidally aligned, non-debris ring-crossing orbit, although astrometry is required firmer conclusions. cannot that b exhibits 0.7–0.8 mag variability cited as...

We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet β Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, precision measurements. While Pic b's near-IR colors mimic those a standard, cloudy early-to-mid L dwarf, it is overluminous mid-infrared compared field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., κ And 1RXJ 1609B—match JHKsL' photometry its...

Strong tidal interaction with the central star can circularize orbits of close-in planets. With standard quality factor Q our solar system, estimated circularization times for extrasolar planets are typically shorter than ages host stars. While most orbital radii a≲ 0.1 AU indeed have circular orbits, some substantial eccentricities recently been discovered. This new class eccentric implies that either their is considerably higher, or prevented by an external perturbation. Here we constrain...

We present new $L^\prime$ (3.8 $μm$) and Br-$α$ (4.05 data reprocessed archival for the young, planet-hosting star HR 8799 obtained with Keck/NIRC2, VLT/NaCo Subaru/IRCS. detect all four planets in each dataset at a moderate to high signal-to-noise (SNR $\gtrsim$ 6-15). fail identify fifth planet, "HR f", $r$ $

The Grand Tack model of terrestrial planet formation has emerged in recent years as the premier scenario used to account for several observed features inner solar system. It relies on early migration giant planets gravitationally sculpt and mix planetesimal disc down ~1 AU, after which accrete from material left a narrow circum-solar annulus. Here we have investigated how fares under range initial conditions course-change (`tack') locations. We run large number N-body simulations with tack...

The orbital distributions of currently observed extrasolar giant planets allow marginally stable orbits for hypothetical, terrestrial planets. In this paper, we propose that many these systems may not have additional on "stable" orbits, since past dynamical instability among could removed them. We numerically investigate the effects early evolution multiple stability inner, sub-Neptune-like which are modeled as test particles, and determine their dynamically unstable region. Previous studies...

We present previously unpublished 2005 July H-band coronagraphic data of the young, planet-hosting star HR 8799 from newly released Keck/NIRC2 archive. Despite poor observing conditions, we detect three planets (HR bcd), two them bc) without advanced image processing. Comparing these with published 1998–2011 astrometry and that re-reduced 2010 October Keck constrains orbits planets. Analyzing planets' separately, d's orbit is likely inclined at least 25° face-on others may be on orbits. For...

The tidal interaction between a disk and planet leads to the planet's migration. A long-standing question regarding this mechanism is how stop migration before planets plunge into their central stars. In paper, we propose new, simple significantly slow down migration, test possibility by using hybrid numerical integrator simulate disk-planet interaction. key component of scenario role low viscosity regions in protostellar disks known as dead zones, which affect planetary two ways. First all,...

We present and analyze a new M' detection of the young exoplanet β Pictoris b from 2008 VLT/NaCo data at separation ≈4 AU high signal-to-noise rereduction L' taken in 2009 December. Based on our orbital analysis, planet's orbit is viewed almost perfectly edge-on (i ∼ 89 deg) has Saturn-like semimajor axis 9.50 AU+3.93 AU− 1.7 AU. Intriguingly, aligned with major outer disk (Ω 31 but probably misaligned warp/inclined 80 AU, often cited as signpost for existence. Our results motivate studies...

Out of the handful asteroids that have been imaged, some distributions blocks are not easily explained. In this paper, we investigate possibility seismic shaking leads to size sorting particles in asteroids. particular, focus on so-called Brazil Nut Effect (BNE) separates large from small ones under vibrations. We study BNE over a wide range parameters by using N-body code PKDGRAV, and find effect is largely insensitive coefficients restitution, but sensitive friction constants oscillation...

Context . Prevailing N -body planet formation models typically start with lunar-mass embryos and show a general trend of rapid migration massive planetary cores to the inner Solar System in absence trap. This setup cannot capture evolution from planetesimal embryo, which is crucial final architecture system. Aims We aim model starting planetesimals ~10 −6 −10 −4 M ⊕ reproduce giant planets System. Methods simulated population 1000-5000 smooth protoplanetary disc, was evolved under effects...

The final masses of Jovian planets are attained when the tidal torques that they exert on their surrounding protostellar disks sufficient to open gaps in face disk viscosity, thereby shutting off any further accretion. In sufficiently well ionized disks, predominant form viscosity originates from magnetorotational instability (MRI) drives hydromagnetic turbulence. region low ionization rate, so-called dead zone, turbulence is damped and we show lower mass will be formed. We considered three...

Most low-mass protostellar discs evolve in clustered environments where they are affected by external radiation fields, while others more isolated star-forming regions. Assuming that the magnetorotational instability (MRI) is main source of viscosity, we calculate size a poorly ionized, MRI inactive and hence low viscosity region — 'dead zone'-in these discs. We include disc ionization X-rays, cosmic rays, radioactive elements thermal collisions, recombination molecules, metals grains, as...

The discovery of over 400 extrasolar planets allows us to statistically test our understanding formation and dynamics planetary systems via numerical simulations. Traditional N-body simulations multiple-planet without gas disks have successfully reproduced the eccentricity (e) distribution observed systems, by assuming that are relatively closely packed when disk dissipates, so they become dynamically unstable within stellar lifetime. However, such studies cannot explain small semi-major...

Context. Planet formation with pebbles has been proposed to solve a couple of long-standing issues in the classical model. Some sophisticated simulations have done confirm efficiency pebble accretion. However, there not any global N-body that compare outcomes planet via accretion observed extrasolar planetary systems. Aims. In this paper, we study effects range initial parameters accretion, and present first results our simulations. Methods. We incorporate model by Ida et al. (2016) code...

Overcoming type I migration and preventing low-mass planets from spiralling into the central star is a long-studied topic. It well known that outward possible in viscous-heated discs relatively close to because entropy gradient can be sufficiently steep positive corotation torque overcomes negative Lindblad torque. Yet efficiently trapping this region remains elusive. Here we study disc conditions yield for under specific planet prescriptions. Using steady-state model with constant...

Recent observations have shown that at least some close-in exoplanets maintain eccentric orbits despite tidal circularization timescales are typically much shorter than stellar ages. We explore gravitational interactions with a more distant planetary companion as possible cause of these unexpected non-zero eccentricities. For simplicity, we focus on the evolution planar two-planet system subject to slow eccentricity damping and provide an intuitive interpretation resulting long-term orbital...

Aims. The connection between initial disc conditions and final orbital physical properties of planets is not well-understood. In this paper, we numerically study the formation planetary systems via pebble accretion investigate effects such as masses, dissipation timescales, metallicities on planet outcomes. Methods. We improved N-body code SyMBA that was modified by taking account new planet-disc interaction models type II migration. adopted 'two-alpha disc' model to mimic both standard...

Many close-in multiple-planet systems show a peas-in-a-pod trend, where sizes, masses, and orbital spacing of neighbouring planets are comparable to each other. On the other hand, some planetary have more diverse black size mass distribution, including Solar System. Classical planet formation models tend produce former type rather than latter, origin their difference is not well understood. Recent observational numerical studies support disc evolution that largely driven by magnetic winds...