2010A&A...513A..19F


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST21:50:02

2010A&A...513A..19F - Astronomy and Astrophysics, volume 513, A19-19 (2010/4-1)

The role of convection, overshoot, and gravity waves for the transport of dust in M dwarf and brown dwarf atmospheres.

FREYTAG B., ALLARD F., LUDWIG H.-G., HOMEIER D. and STEFFEN M.

Abstract (from CDS):

Observationally, spectra of brown dwarfs indicate the presence of dust in their atmospheres while theoretically it is not clear what prevents the dust from settling and disappearing from the regions of spectrum formation. Consequently, standard models have to rely on ad hoc assumptions about the mechanism that keeps dust grains aloft in the atmosphere. We apply hydrodynamical simulations to develop an improved physical understanding of the mixing properties of macroscopic flows in M dwarf and brown dwarf atmospheres, in particular of the influence of the underlying convection zone. We performed two-dimensional radiation hydrodynamics simulations including a description of dust grain formation and transport with the CO5BOLD code. The simulations cover the very top of the convection zone and the photosphere including the dust layers for a sequence of effective temperatures between 900K and 2800K, all with logg=5 assuming solar chemical composition. Convective overshoot occurs in the form of exponentially declining velocities with small scale heights, so that it affects only the region immediately above the almost adiabatic convective layers. From there on, mixing is provided by gravity waves that are strong enough to maintain thin dust clouds in the hotter models. With decreasing effective temperature, the amplitudes of the waves become smaller but the clouds become thicker and develop internal convective flows that are more efficient in transporting and mixing material than gravity waves. The presence of clouds often leads to a highly structured appearance of the stellar surface on short temporal and small spatial scales (presently inaccessible to observations). We identify convectively excited gravity waves as an essential mixing process in M dwarf and brown dwarf atmospheres. Under conditions of strong cloud formation, dust convection is the dominant self-sustaining mixing component.

Abstract Copyright:

Journal keyword(s): brown dwarfs - hydrodynamics - convection - waves - stars: atmospheres - stars: low-mass

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 * eps Ind B BD* 22 04 10.52064 -56 46 57.7452     24.12 20.8 15.60 T1V+T6V 129 2

    Equat.    Gal    SGal    Ecl

C.D.S. - SIMBAD4 rel 1.7 - 2020.07.14CEST21:50:02

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


Basic data :
* eps Ind B -- Brown Dwarf (M<0.08solMass)
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:
IR (2MASS,WISEA,...), ** (Ref,**,...), * (*,GJ,...), PM* (Ref,2016ApJS..224...36K), BD* (Ref), V* (V*), Rad ([B2006])
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) :
22 04 10.52064 -56 46 57.7452 (Near-IR) [ 60 60 90 ] C 2003yCat.2246....0C
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) :
22 00 22.30042 -56 59 27.1019 [ 60 60 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) :
336.12090835 -48.14563949 [ 60 60 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 :
3955.59 -2464.29 [0.77 12.85 90] C 2016AJ....152...24W
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas):
275.79 [0.69] A 1997A&A...323L..49P
Spectral type is made of 3 parts: %coding is composed of 4 parts :
  • the spectral type, which is made of a temperature class, eventually a luminosity class (roman number) and/or spectral peculiarities;
  • a quality letter: A=best quality→E=worst quality, {� } =unknown quality %
  • a quality letter: A=best quality -> E=worst quality, {� } =unknown quality
  • bibcode : bibcode of the spectral type reference
Spectral type:
T1V+T6V C 2005AJ....129.2849B
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
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • 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 (8) :
V 24.12 [0.03] D 2010A&A...510A..99K
R 20.8 [~] D 2007ApJ...658..557B
G 18.5914 [0.0832] C 2018yCat.1345....0G
I 15.60 [~] D 2006IBVS.5721....1K
J 11.908 [0.022] C 2003yCat.2246....0C
H 11.306 [0.024] C 2003yCat.2246....0C
K 11.208 [0.021] C 2003yCat.2246....0C
z 15.07 [0.02] D 2010A&A...510A..99K
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Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!).
Some important notes on this object about identifications and objects associations.
notes:

  • * Eps Ind B is associated with source 1WGA J2203.9-5647 in 2004MNRAS.354..913B (separation about 30arcsec).
  • GJ 845 B is WDS J22034-5647Ba and GJ 845 C is WDS J22034-5647Bb in the literature.


The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (14) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

2MASS J22041052-5646577 GJ 845 B WDS J22034-5647B [B2006] J220410.5-564657
* eps Ind B GJ 845 C WISEA J220415.75-564724.4 Gaia DR2 6412596012146094848
** VLK 1 V* CI Ind WISEP J220415.66-564723.5
** SOZ 1B WDS J22034-5647Ba,Bb WISE J220415.65-564723.6

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References (129 between 1850 and 2020) (Total 129)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


distance : 2    PM : 3    PLX : 1    MK : 11   

   


External archives :

Link by name to the catalogue in VizieR :

2MASS J22041052-5646577 GJ 845 B GJ 845 C V* CI Ind WDS J22034-5647Ba,Bb
WDS J22034-5647B WISEA J220415.75-564724.4 WISE J220415.65-564723.6 Gaia DR2 6412596012146094848

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2020.07.14-21:50:02

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