Hydrogen Recombination Line Luminosities and Variability from Forming Planets

We calculated hydrogen recombination line luminosities (H-$\alpha$, Paschen-$\beta$ and Brackett-$\gamma$) from three dimensional thermo-hydrodynamical simulations of forming planets from 1 to 10 Jupiter-masses. We explored various opacities to estimate the line emissions with extinction in each cases assuming boundary layer accretion. When realistic opacities are considered, only lines from planets $\ge$10 Jupiter-mass can be detected with current instrumentation, highlighting that from most planets one cannot expect detectable emission. This might explain the very low detection rate of H-$\alpha$ from forming planets from observations. While the line emission comes from both the forming planet and its circumplanetary disk, we found that only the disk component could be detected due to extinction. We examined the line variability as well, and found that it is higher for higher mass planets. Furthermore, we determine for the first time, the parametric relationship between the mass of the planet and the luminosity of the hydrogen recombination lines, as well as the equation between the accretion luminosity and hydrogen recombination line luminosities.

[1]  H. Canovas,et al.  The widest Hα survey of accreting protoplanets around nearby transition disks , 2019 .

[2]  C. U. Keller,et al.  Two accreting protoplanets around the young star PDS 70 , 2019, Nature Astronomy.

[3]  Elvira Covino,et al.  X-shooter spectroscopy of young stellar objects: I - Mass accretion rates of low-mass T Tauri stars in \sigma Orionis , 2012, 1209.5799.

[4]  D. Lin,et al.  USING FU ORIONIS OUTBURSTS TO CONSTRAIN SELF-REGULATED PROTOSTELLAR DISK MODELS , 1993, astro-ph/9312015.

[5]  K. Menou,et al.  DISK-FED GIANT PLANET FORMATION , 2016, 1602.02781.

[6]  Julien H. Girard,et al.  A search for accreting young companions embedded in circumstellar disks , 2018, Astronomy & Astrophysics.

[7]  T. Guillot,et al.  Circumplanetary disc or circumplanetary envelope , 2016, 1605.04586.

[8]  S. Warren,et al.  Optical constants of ice from the ultraviolet to the microwave: A revised compilation , 2008 .

[9]  P. Schneider,et al.  Spectro-astrometry of the pre-transitional star LkCa 15 does not reveal an accreting planet but extended Hα emission , 2018, Astronomy & Astrophysics.

[10]  Zhaohuan Zhu,et al.  ACCRETING CIRCUMPLANETARY DISKS: OBSERVATIONAL SIGNATURES , 2014, 1408.6554.

[11]  Jack J. Lissauer,et al.  Formation of the Giant Planets by Concurrent Accretion of Solids and Gas , 1995 .

[12]  H. M. Lee,et al.  Optical properties of interstellar graphite and silicate grains , 1984 .

[13]  B. Ercolano,et al.  X-Ray Enabled MOCASSIN: A Three-dimensional Code for Photoionized Media , 2007, 0710.2103.

[14]  Jonathan P. Williams,et al.  Protoplanetary Disks and Their Evolution , 2011, 1103.0556.

[15]  B. Draine.  Scattering by Interstellar Dust Grains. II. X-Rays , 2003, astro-ph/0308251.

[16]  Sean M. Andrews,et al.  PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS , 2009, 0906.0730.

[17]  Megh Nad Saha D.Sc..  LIII. Ionization in the solar chromosphere , 2009 .

[18]  MOCASSIN: a fully three-dimensional Monte Carlo photoionization code , 2002, astro-ph/0209378.

[19]  A. Youdin,et al.  MINIMUM CORE MASSES FOR GIANT PLANET FORMATION WITH REALISTIC EQUATIONS OF STATE AND OPACITIES , 2014, 1412.5185.

[20]  K. Batygin.  On the Terminal Rotation Rates of Giant Planets , 2018, 1803.07106.

[21]  Matthew R. Bate,et al.  Gas accretion on to planetary cores: three-dimensional self-gravitating radiation hydrodynamical calculations , 2008, 0811.1259.

[22]  E. Chiang,et al.  GAP OPENING IN 3D: SINGLE-PLANET GAPS , 2016, 1606.02299.

[23]  Laird M. Close,et al.  Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk , 2018, The Astrophysical Journal Letters.

[24]  R. Nelson,et al.  GLOBAL HYDROMAGNETIC SIMULATIONS OF A PLANET EMBEDDED IN A DEAD ZONE: GAP OPENING, GAS ACCRETION, AND FORMATION OF A PROTOPLANETARY JET , 2013, 1309.2871.

[25]  S. Okuzumi,et al.  A FAST AND ACCURATE CALCULATION SCHEME FOR IONIZATION DEGREES IN PROTOPLANETARY AND CIRCUMPLANETARY DISKS WITH CHARGED DUST GRAINS , 2011, 1106.3528.

[26]  W. Kley.  Mass flow and accretion through gaps in accretion discs , 1998, astro-ph/9809253.

[27]  K. Ohtsuki,et al.  DISTRIBUTION OF ACCRETING GAS AND ANGULAR MOMENTUM ONTO CIRCUMPLANETARY DISKS , 2011, 1112.3706.

[28]  A. Crida,et al.  ACCRETION OF JUPITER-MASS PLANETS IN THE LIMIT OF VANISHING VISCOSITY , 2013, 1312.6302.

[29]  K. Nordsieck,et al.  The Size distribution of interstellar grains , 1977 .

[30]  A. Skemer,et al.  Accreting protoplanets in the LkCa 15 transition disk , 2015, Nature.

[31]  M. Ikoma,et al.  Theoretical Model of Hydrogen Line Emission from Accreting Gas Giants , 2018, The Astrophysical Journal.

[32]  J. Carpenter,et al.  STRUCTURE AND EVOLUTION OF PRE-MAIN-SEQUENCE CIRCUMSTELLAR DISKS , 2009, 0906.2227.

[33]  J. Szulágyi,et al.  Observability of forming planets and their circumplanetary discs II. – SEDs and near-infrared fluxes , 2019, Monthly Notices of the Royal Astronomical Society.

[34]  J. Szulágyi,et al.  Effects of the Planetary Temperature on the Circumplanetary Disk and on the Gap , 2017, 1705.08444.

[35]  C. Mordasini,et al.  The Planetary Accretion Shock. II. Grid of Postshock Entropies and Radiative Shock Efficiencies for Nonequilibrium Radiation Transport , 2019, The Astrophysical Journal.

[36]  P. J. Storey,et al.  The dusty MOCASSIN: fully self-consistent 3D photoionization and dust radiative transfer models , 2005, astro-ph/0507050.

[37]  C. Mordasini,et al.  Thermodynamics of giant planet formation: shocking hot surfaces on circumplanetary discs , 2016, 1609.08652.

[38]  Johns Hopkins University,et al.  Disk Accretion onto High-Mass Planets , 1999 .

[39]  L. Colangeli,et al.  Optical constants of cosmic carbon analogue grains — I. Simulation of clustering by a modified continuous distribution of ellipsoids , 1996 .

[40]  S. Okuzumi,et al.  ON THE VIABILITY OF THE MAGNETOROTATIONAL INSTABILITY IN CIRCUMPLANETARY DISKS , 2014, 1402.6091.

[41]  U. Christensen,et al.  Energy flux determines magnetic field strength of planets and stars , 2009, Nature.

[42]  R. Teyssier,et al.  Radiation hydrodynamics with adaptive mesh refinement and application to prestellar core collapse. I. Methods , 2011, 1102.1216.

[43]  E. Bergin,et al.  Meridional flows in the disk around a young star , 2019, Nature.

[44]  M. Bate,et al.  The growth and hydrodynamic collapse of a protoplanet envelope , 2012, 1208.5513.

[45]  M. N. Saha.  LIII. Ionization in the solar chromosphere , 1920 .

[46]  M. Bate,et al.  Circumplanetary disc properties obtained from radiation hydrodynamical simulations of gas accretion by protoplanets , 2009, 0904.4884.

[47]  L. Testi,et al.  X-shooter spectroscopy of young stellar objects. IV. Accretion in low-mass stars and substellar objects in Lupus , 2013, 1310.2069.

[48]  J. Dra̧żkowska,et al.  Dust Evolution and Satellitesimal Formation in Circumplanetary Disks , 2018, The Astrophysical Journal.