2009A&A...506.1367W


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.12CET00:38:59

2009A&A...506.1367W - Astronomy and Astrophysics, volume 506, 1367-1380 (2009/11-2)

Dust in brown dwarfs and extra-solar planets. II. Cloud formation for cosmologically evolving abundances.

WITTE S., HELLING C. and HAUSCHILDT P.H.

Abstract (from CDS):

Substellar objects have extremely long life spans. The cosmological consequence for older objects are low abundances for heavy elements, which in turn results in a wide distribution of objects over metallicity, hence over age. Within their cool atmosphere, dust clouds become a dominant feature, affecting the opacity and the remaining gas phase abundance of heavy elements. We investigate the influence of the stellar metallicity on the dust formation in substellar atmospheres and on the dust cloud structure and its feedback on the atmosphere. This work has implications for the general questions of star formation and of dust formation in the early universe. We utilise numerical simulations to solve a set of moment equations to determine the quasi-static dust cloud structure (Drift). These equations model the nucleation, the kinetic growth of composite particles, their evaporation, and the gravitational settling as a stationary dust formation process. Element conservation equations augment this system of equations by including the element replenishment by convective overshooting. The integration with an atmosphere code (Phoenix) allows determination of a consistent (T, p, vconv)-structure (T-local temperature, p-local pressure, vconv-convective velocity), hence, to calculate synthetic spectra. A grid of Drift-Phoenix model atmospheres was calculated for a wide range of metallicity, [M/H]in[+0.5, -0.0, -0.5, ..., -6.0], to allow for systematic study of atmospheric cloud structures throughout the evolution of the universe. We find dust clouds in even the most metal-poor ([M/H]=-6.0) atmosphere of brown dwarfs. Only the most massive among the youngest brown dwarfs and giant gas planets can resist dust formation. For very low heavy element abundances, a temperature inversion develops that has a drastic impact on the dust cloud structure. The combination of metal depletion by dust formation and the uncertainty of interior element abundances makes the modelling of substellar atmospheres an intricate problem in particular for old substellar objects. We furthermore show that the dust-to-gas ratio does not scale linearly with the object's [M/H] for a given effective temperature. The mean grain sizes and the composition of the grains change depending on [M/H], which influences the dust opacity that determines radiative heating and cooling, as well as the spectral appearance.

Abstract Copyright:

Journal keyword(s): astrochemistry - methods: numerical - stars: atmospheres - stars: low-mass, brown dwarfs

Simbad objects: 1

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Number of rows : 1

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Carina dSph G 06 41 36.7 -50 57 58   22.14 11.0 19.47   ~ 955 0

    Equat.    Gal    SGal    Ecl

C.D.S. - SIMBAD4 rel 1.7 - 2019.11.12CET00:38:59

Available data : Basic data  •  Identifiers  •  Plot & images  •  Bibliography  •  Measurements  •  External archives  •  Notes  •  Annotations


Basic data :
NAME Carina dSph -- Galaxy
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types:
G (Ref,AM,...)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
06 41 36.7 -50 57 58 [ 8000 8000 90 ] D 1982ESO...C......0L
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
06 40 24.0 -50 55 00 [ 8000 8000 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
260.1124 -22.2235 [ 8000 8000 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr :
0.220 0.150 [0.090 0.090 ] C 2003AJ....126.2346P
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz :
V(km/s) 222.9 [0.1] / z(spectroscopic) 0.000744 [0.000000] / cz 222.98 [0.10]
   C 2012AJ....144....4M
Syntax of morphological type is : mtype quality bibcode
  • mtype : Hubble morphological class (spirals, ellipticals, etc)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
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Morphological type:
dSph D 2012AJ....144....4M
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (incl) : inclination (in units of 15° from 0 to 7)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin):
19.9333 19.9333 0 (~) D 2008MNRAS.389.1924F
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
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  • flux-value : value of flux or magnitude
  • [error] : error value
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  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (4) :
B 22.14 [~] C 1989ESOLV.C......0L
V 11.0 [0.5] D 2012AJ....144....4M
R 19.47 [~] C 1989ESOLV.C......0L
K 8.68 [~] D 2008MNRAS.389.1924F
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Hierarchy : number of linked objects
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: 3
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Identifiers (13) :
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NAME Car dSph LEDA 19441 NAME Carina dSph EQ 0640-509
AM 0640-505 NAME Carina Galaxy SGC 064024-5055.0
ESO 206-20A NAME Car Dwarf Galaxy [FG85] 193
ESO-LV 206-2200 NAME Carina Dwarf Galaxy [VDD93] 55

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References (955 between 1850 and 2020) (Total 955)
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distance : 5    velocities : 2    Fe_H : 1   

   

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External archives :

Data at NED - NASA/IPAC Extragalactic Database : NAME Carina dSph

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ESO-LV 206-2200

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2019.11.12-00:38:59

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