J/ApJ/745/174 Evolutionary models of young gas-giant planets (Spiegel+, 2012) ================================================================================ Spectral and photometric diagnostics of giant planet formation scenarios. Spiegel D.S., Burrows A. =2012ApJ...745..174S ================================================================================ ADC_Keywords: Models, evolutionary ; Planets ; Stars, double and multiple Keywords: brown dwarfs - radiative transfer - stars: evolution - stars: low-mass Abstract: Gas-giant planets that form via core accretion might have very different characteristics from those that form via disk instability. Disk-instability objects are typically thought to have higher entropies, larger radii, and (generally) higher effective temperatures than core-accretion objects. In this paper, we provide a large set of models exploring the observational consequences of high-entropy (hot) and low-entropy (cold) initial conditions, in the hope that this will ultimately help to distinguish between different physical mechanisms of planet formation. However, the exact entropies and radii of newly formed planets due to these two modes of formation cannot, at present, be precisely predicted. It is possible that the distribution of properties of core-accretion-formed planets and the distribution of properties of disk-instability-formed planets overlap. We, therefore, introduce a broad range of "warm-start" gas-giant planet models. Between the hottest and the coldest models that we consider, differences in radii, temperatures, luminosities, and spectra persist for only a few million to a few tens of millions of years for planets that are a few times Jupiter's mass or less. For planets that are ~five times Jupiter's mass or more, significant differences between hottest-start and coldest-start models persist for on the order of 100 Myr. We find that out of the standard infrared bands (J, H, K, L', M, N) the K and H bands are the most diagnostic of the initial conditions. A hottest-start model can be from ~4.5 mag brighter (at Jupiter's mass) to ~9 mag brighter (at 10 times Jupiter's mass) than a coldest-start model in the first few million years. In more massive objects, these large differences in luminosity and spectrum persist for much longer than in less massive objects. Finally, we consider the influence of atmospheric conditions on spectra, and find that the presence or absence of clouds, and the metallicity of an atmosphere, can affect an object's apparent brightness in different bands by up to several magnitudes. Description: In this paper, we build on previous work by examining the photometric and spectral signatures of a wide range of initial conditions, and the influence on spectra of different atmosphere types. In order to explore the range of initial entropies that are reasonable within the core-accretion context, we have computed a large number of new evolutionary models. We employ the boundary conditions of Burrows et al. (1997ApJ...491..856B), and we assume with M07 (Marley et al. 2007ApJ...655..541M) that the infalling gas radiates until it is at the same entropy as the gas already present. Figure 1 displays our new models and the M07 ones. See section 2. The differences in entropy, radius, and effective temperature between "hot-start" and "cold-start" models translate into differences in spectra and broadband magnitudes. In order to compute spectra, we assume various atmospheres. In particular, we consider four atmosphere types from Burrows et al. (2011ApJ...736...47B): hybrid clouds at solar metallicity (our "fiducial" atmospheres), hybrid clouds at 3x solar metallicity, cloud-free atmospheres at solar metallicity, and cloud-free at 3x solar metallicity. Our planets are modeled as isolated objects, assumed to be in radiative equilibrium, and their emergent spectra are calculated with the line-by-line radiative transfer code COOLTLUSTY (Hubeny et al. 2003ApJ...594.1011H; Burrows et al. 2006ApJ...650.1140B). See Figures 6 and 7 in section 4.3. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 99 176 Evolution of multi-band magnitudes (hybrid clouds and solar abundance) mag/* . 4 *The four files that show the evolution of radius and of absolute magnitudes in H, J, K, L', M, and N bands as functions of initial entropy and age. list.dat 45 1680 Summary of the 1680 spectra contained in the subdirectory spectra spectra/* . 1680 Individual spectrum following 4 atmospheres, 15 masses and 28 ages -------------------------------------------------------------------------------- Note on mag/*: The filename specifies the mass in units of Jupiter's mass. -------------------------------------------------------------------------------- Description of file: spectra/* The file names indicate the combination (mass in Mjup and Age in Myr). Each file contains the following rows: Row #: Value 1: column 1: Age (Myr); columns 2-601: wavelength (in microns, in range 0.8-15.0) 2-end: column 1: initial entropy; columns 2-601: F_nu (in mJy for a source at 10 pc) Row 1 contains the wavelength scale (in columns 2-601) for a moderate resolution (R=200) spectrum. In rows 2-end, where the spectra appear, the source is assumed to be at a distance of 10pc. Initial entropies increase from 8.0 to the minimum of 13.0 and the maximum stable initial entropy that we could calculate, in increments of 0.25. See also: J/AJ/143/39 : Analysis of hot Jupiters in Kepler Q2 (Coughlin+, 2012) J/A+A/547/A105 : D-burning in core accretion objects (Molliere+, 2012) J/ApJ/692/L9 : Tidal evolution of transiting exoplanets (Levrard+, 2009) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Model Model type (G1) (1) 6- 11 F6.2 Myr Age [1/100] Age 13- 17 F5.2 Mjup Mass [1/10] Mass 19- 22 F4.2 Rjup R.h Hot-start model radius (1) 24- 28 F5.2 mag Jmag.h Hot-start model J band magnitude (1) 30- 34 F5.2 mag Hmag.h Hot-start model H band magnitude (1) 36- 40 F5.2 mag Kmag.h Hot-start model K band magnitude (1) 42- 46 F5.2 mag Lmag.h Hot-start model L' band magnitude (1) 48- 52 F5.2 mag Mmag.h Hot-start model M band magnitude (1) 54- 58 F5.2 mag Nmag.h Hot-start model N band magnitude (1) 60- 63 F4.2 Rjup R.c Cold-start model radius (1) 65- 69 F5.2 mag Jmag.c Cold-start model J band magnitude (1) 71- 75 F5.2 mag Hmag.c Cold-start model H band magnitude (1) 77- 81 F5.2 mag Kmag.c Cold-start model K band magnitude (1) 83- 87 F5.2 mag Lmag.c Cold-start model L' band magnitude (1) 89- 93 F5.2 mag Mmag.c Cold-start model M band magnitude (1) 95- 99 F5.2 mag Nmag.c Cold-start model N band magnitude (1) -------------------------------------------------------------------------------- Note (1): The "hot-start" model represents disk-instability planets (high initial entropy), and the "cold-start" model a formation via core accretion (low initial entropy). The corresponding data are illustrated in Figure 7. -------------------------------------------------------------------------------- Byte-by-byte Description of file: mag/* -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 13 E13.7 --- Sinit [8/13] Initial entropy, in k per baryon (k=Boltzmann's constant) 15- 27 E13.7 Myr Age Age of planet 29- 41 E13.7 Rjup R Radius of planet 43- 55 E13.7 mag Hmagh1 hy1s atmosphere absolute H band magnitude (1) 57- 69 E13.7 mag Hmagh3 hy3s atmosphere absolute H band magnitude (1) 71- 83 E13.7 mag Hmagc1 cf1s atmosphere absolute H band magnitude (1) 85- 97 E13.7 mag Hmagc3 cf3s atmosphere absolute H band magnitude (1) 99-111 E13.7 mag Jmagh1 hy1s atmosphere absolute J band magnitude (1) 113-125 E13.7 mag Jmagh3 hy3s atmosphere absolute J band magnitude (1) 127-139 E13.7 mag Jmagc1 cf1s atmosphere absolute J band magnitude (1) 141-153 E13.7 mag Jmagc3 cf3s atmosphere absolute J band magnitude (1) 155-167 E13.7 mag Kmagh1 hy1s atmosphere absolute K band magnitude (1) 169-181 E13.7 mag Kmagh3 hy3s atmosphere absolute K band magnitude (1) 183-195 E13.7 mag Kmagc1 cf1s atmosphere absolute K band magnitude (1) 197-209 E13.7 mag Kmagc3 cf3s atmosphere absolute K band magnitude (1) 211-223 E13.7 mag Lmagh1 hy1s atmosphere absolute L' band magnitude (1) 225-237 E13.7 mag Lmagh3 hy3s atmosphere absolute L' band magnitude (1) 239-251 E13.7 mag Lmagc1 cf1s atmosphere absolute L' band magnitude (1) 253-265 E13.7 mag Lmagc3 cf3s atmosphere absolute L' band magnitude (1) 267-279 E13.7 mag Mmagh1 hy1s atmosphere absolute M' band magnitude (1) 281-293 E13.7 mag Mmagh3 hy3s atmosphere absolute M' band magnitude (1) 295-307 E13.7 mag Mmagc1 cf1s atmosphere absolute M' band magnitude (1) 309-321 E13.7 mag Mmagc3 cf3s atmosphere absolute M' band magnitude (1) 323-335 E13.7 mag Nmagh1 hy1s atmosphere absolute N band magnitude (1) 337-349 E13.7 mag Nmagh3 hy3s atmosphere absolute N band magnitude (1) 351-363 E13.7 mag Nmagc1 cf1s atmosphere absolute N band magnitude (1) 365-377 E13.7 mag Nmagc3 cf3s atmosphere absolute N band magnitude (1) -------------------------------------------------------------------------------- Note (1): * The models are: cf1s = cloud-free atmosphere with solar matellacity cf3s = cloud-free atmosphere with 3x solar matellacity hy1s = hybrid clouds with solar matellacity hy3s = hybrid clouds with 3x solar matellacity * The flux zero points used for computing these magnitudes are: J0 = 1560Jy (1.56e-20 erg/cm^2^/s/Hz) H0 = 1040Jy (1.04e-20 erg/cm^2^/s/Hz) K0 = 645Jy (6.45e-21 erg/cm^2^/s/Hz) L'0 = 246Jy (2.49e-21 erg/cm^2^/s/Hz) M0 = 163Jy (1.63e-21 erg/cm^2^/s/Hz) N0 = 39.8Jy (3.98e-22 erg/cm^2^/s/Hz) * That is, in band X, with zero point X0, the magnitude is M(X)=-2.5log10[F(X)/X0], where F(X) is the X-band flux, integrated over the band-pass. -------------------------------------------------------------------------------- Byte-by-byte Description of file: list.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 4 A4 --- Model Model (G1) 6- 8 I3 Mjup Mass Mass 10- 13 I4 Myr Age Age 15- 45 A31 --- FileName Name of the file in subdirectory spectra (see the "Description of file: spectra/*" section above) -------------------------------------------------------------------------------- Global note: Note (G1): Model as follows: cf1s = cloud-free at solar abundance of metals; cf3s = cloud-free at 3X solar abundance. hy1s = hybrid clouds at solar abundance of metals; hy3s = hybrid clouds at 3X solar abundance; -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 02-Aug-2013