J/ApJ/823/108 A dust model for bet Pic from 0.58 to 870um (Ballering+, 2016)
A comprehensive dust model applied to the resolved beta Pictoris debris disk
from optical to radio wavelengths.
Ballering N.P., Su K.Y.L., Rieke G.H., Gaspar A.
<Astrophys. J., 823, 108 (2016)>
=2016ApJ...823..108B 2016ApJ...823..108B (SIMBAD/NED BibCode)
ADC_Keywords: Models
Keywords: circumstellar matter; planetary systems; stars: individual: * bet Pic
Abstract:
We investigate whether varying the dust composition (described by the
optical constants) can solve a persistent problem in debris disk
modeling --the inability to fit the thermal emission without
overpredicting the scattered light. We model five images of the β
Pictoris disk: two in scattered light from the Hubble Space Telescope
(HST)/Space Telescope Imaging Spectrograph at 0.58µm and HST/Wide
Field Camera 3 (WFC3) at 1.16µm, and three in thermal emission from
Spitzer/Multiband Imaging Photometer for Spitzer (MIPS) at 24µm,
Herschel/PACS at 70µm, and Atacama Large Millimeter/submillimeter
Array at 870µm. The WFC3 and MIPS data are published here for the
first time. We focus our modeling on the outer part of this disk,
consisting of a parent body ring and a halo of small grains. First, we
confirm that a model using astronomical silicates cannot
simultaneously fit the thermal and scattered light data. Next, we use
a simple generic function for the optical constants to show that
varying the dust composition can improve the fit substantially.
Finally, we model the dust as a mixture of the most plausible debris
constituents: astronomical silicates, water ice, organic refractory
material, and vacuum. We achieve a good fit to all data sets with
grains composed predominantly of silicates and organics, while ice and
vacuum are, at most, present in small amounts. This composition is
similar to one derived from previous work on the HR 4796A disk. Our
model also fits the thermal spectral energy distribution, scattered
light colors, and high-resolution mid-IR data from T-ReCS for this
disk. Additionally, we show that sub-blowout grains are a necessary
component of the halo.
Description:
β Pic was imaged with the HST/STIS CCD in coronagraphic (50CORON)
mode under program GO-12551 (PI: Apai), and the results of these
observations were published in Apai et al. (2015ApJ...800..136A 2015ApJ...800..136A).
The instrument bandpass is set by the response of the CCD and centered
at 0.58um.
We searched the HST archive and found previously unpublished
observations of β Pic with the WFC3 instrument in the IR channel
(filter F110W at ∼1.16um) from program GO-11150 (PI: Graham).
The Spitzer/MIPS observations of β Pic were taken under the
Spitzer Guaranteed Time Observing Program 90 (PI: M. Werner). The data
at all three bands (24, 70, and 160um) are published here for the
first time. Two sets of 24um observations were obtained. The first set
was obtained on 2004 March 20, the second set of data was obtained on
2004 April 11. Two sets of 70um observations were obtained. The first
set was obtained on 2004 April 12. The second set was obtained on 2005
April 4.
Herschel/PACS 70um scan map observations of β Pic (PI G.
Olofsson, observation IDs 1342186612 and 1342186613) were published by
Vandenbussche et al. (2010A&A...518L.133V 2010A&A...518L.133V).
We used the ALMA 870um continuum image previously published by Dent et
al. (2014Sci...343.1490D 2014Sci...343.1490D).
Objects:
---------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------
05 47 17.09 -51 03 59.4 β Pictoris = * bet Pic
---------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 23 1000 *Optical constants of the best fit model
(60% Astronomical Silicates,
40% Organic Refractory Material);
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Note on table3.dat: The parameters of the best fit model (of the NE side)
are summarized in Table 2 below:
------------------------------------------------
Parameter Value for best model
------------------------------------------------
rin 45au
halo rout 1800au
PB rout 150au
halo p 2.4
PB p 0.5
halo amin 0.1um
atran 5um
PB amax 5000um (1)
halo q 3
PB q 3.65
fsil 0.6
fice 0
forg 0.4
fvac 0
Mhalo 1.13x10-2M{earth}
MPB 7.49x10-2M{earth}
-------------------------------------------------
Note (1): This value was fixed prior to fitting.
-------------------------------------------------
See section 6.4 for further explanations.
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See also:
J/ApJS/211/25 : Spitzer/IRS debris disk catalog. I. (Chen+, 2014)
J/ApJ/777/160 : NIR survey for planets around MG stars (Biller+, 2013)
J/ApJ/775/55 : Spitzer IR excesses in A-K stars (Ballering+, 2013)
J/ApJ/745/147 : Binaries among debris disk stars (Rodriguez+, 2012)
J/A+A/542/A18 : βPic Harps radial velocity data (Lagrange+, 2012)
J/PASP/119/994 : MIPS 24um calibrators (Engelbracht+, 2007)
J/ApJ/660/1556 : Characterization of dusty debris disks (Rhee+, 2007)
J/ApJ/653/675 : Spitzer 24µm photometry of A dwarfs (Su+, 2006)
J/ApJ/620/1010 : Spitzer 24µm photometry of A dwarfs (Rieke+, 2005)
J/MNRAS/304/733 : Beta Pictoris 1994-96 (Petterson+, 1999)
J/A+A/299/557 : Light variations on Beta Pic (Lecavelier des Etangs+, 1995)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 um lambda [0.09/10000] Wavelength
11- 16 F6.4 --- n [1.4/2.92] The n optical constant
18- 23 F6.4 --- k [0.008/0.86] The k optical constant
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Aug-2016