J/ApJ/768/25 Spitzer and Herschel observations of debris disks (Gaspar+, 2013)
The collisional evolution of debris disks.
Gaspar A., Rieke G.H., Balog Z.
<Astrophys. J., 768, 25 (2013)>
=2013ApJ...768...25G 2013ApJ...768...25G
ADC_Keywords: Photometry, infrared ; Stars, ages ; Spectral types
Keywords: circumstellar matter; infrared: stars; methods: numerical
planetary systems
Abstract:
We explore the collisional decay of disk mass and infrared emission in
debris disks. With models, we show that the rate of the decay varies
throughout the evolution of the disks, increasing its rate up to a
certain point, which is followed by a leveling off to a slower value.
The total disk mass falls off ∝t-0.35 at its fastest point
(where t is time) for our reference model, while the dust mass and its
proxy -the infrared excess emission- fades significantly faster
(∝t-0.8). These later level off to a decay rate of
Mtot(t)∝t-0.08 and Mdust(t) or Lir(t)∝t-0.6.
This is slower than the ∝t.-1 decay given for all three
system parameters by traditional analytic models. We also compile an
extensive catalog of Spitzer and Herschel 24, 70, and 100µm
observations. Assuming a log-normal distribution of initial disk
masses, we generate model population decay curves for the fraction of
stars harboring debris disks detected at 24µm. We also model the
distribution of measured excesses at the far-IR wavelengths
(70-100µm) at certain age regimes. We show general agreement at
24µm between the decay of our numerical collisional population
synthesis model and observations up to a Gyr. We associate offsets
above a Gyr to stochastic events in a few select systems. We cannot
fit the decay in the far-infrared convincingly with grain strength
properties appropriate for silicates, but those of water ice give fits
more consistent with the observations (other relatively weak grain
materials would presumably also be successful). The oldest disks have
a higher incidence of large excesses than predicted by the model;
again, a plausible explanation is very late phases of high dynamical
activity around a small number of stars. Finally, we constrain the
variables of our numerical model by comparing the evolutionary trends
generated from the exploration of the full parameter space to
observations. Amongst other results, we show that erosive collisions
are dominant in setting the timescale of the evolution and that
planetesimals on the order of 100 km in diameter are necessary in the
cascades for our population synthesis models to reproduce the
observations.
Description:
We compiled an extensive catalog of 24-100um observations of sources
with reliable photometry and ages from various sources.
Spitzer 24 and 70um data for field stars were obtained from Sierchio
et al. (2014ApJ...785...33S 2014ApJ...785...33S), Su et al. (2006, J/ApJ/653/675), and K.
Y. L. Su (2012, private communication). We added 24um data from a
number of stellar cluster studies (see section 3).
Publicly available PACS 70 and 100um data from the Herschel DEBRIS
(Matthews 2008cosp...37.1957M 2008cosp...37.1957M; Matthews et al. 2010A&A...518L.135M 2010A&A...518L.135M)
and DUNES (Eiroa 2010cosp...38.2471E 2010cosp...38.2471E; Eiroa et al.
2010A&A...518L.131E 2010A&A...518L.131E, 2011A&A...536L...4E 2011A&A...536L...4E) surveys were also obtained
from the Herschel Science Archive data archive.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 147 374 Photometry of the DEBRIS and DUNES Surveys
refs.dat 80 29 References
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See also:
VI/139 : Herschel Observation Log (Herschel Science Centre, 2013)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/A+A/555/A11 : DUNES survey observational results (Eiroa+, 2013)
J/AJ/143/135 : Ages of A-K type stars in DEBRIS survey (Vican, 2012)
J/ApJ/750/98 : 24um obs. of AFGKM stars of 3 clusters (Urban+, 2012)
J/ApJ/738/122 : ScoCen debris disks Around F- and G-type stars (Chen+, 2011)
J/A+A/531/A8 : Activity indexes & velocities for 890 stars (Jenkins+, 2011)
J/AZh/88/1217 : Solar-like activity of low-mass stars (Kasova+, 2011)
J/A+A/520/A79 : Nearby stars chromospheric activity (Martinez-Arnaiz+, 2010)
J/MNRAS/403/1089 : SUNS and DEBRIS surveys target selection (Phillips+, 2010)
J/ApJ/698/1989 : Spitzer survey of NGC 2451 (Balog+, 2009)
J/ApJ/697/1578 : A debris disk study of Praesepe (Gaspar+, 2009)
J/ApJS/179/451 : IR excesses for protoplanetary disks (Kenyon+, 2008)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/A+A/483/903 : Mt Wilson index for main sequence F-K stars (Buccino+, 2008)
J/PASP/119/994 : MIPS 24um calibrators (Engelbracht+, 2007)
J/ApJ/670/516 : NGC 2547 4.5-8um photometry (Gorlova+, 2007)
J/AJ/133/2524 : Spectra of young nearby stars (White+, 2007)
J/ApJ/653/675 : Spitzer 24µm photometry of A dwarfs (Su+, 2006)
J/ApJ/636/1098 : Debris disks around solar-type stars (Bryden+, 2006)
J/MNRAS/372/163 : Activity indices for southern stars (Jenkins+, 2006)
J/AJ/132/161 : NStars project: The southern sample. I. (Gray+, 2006)
J/ApJ/620/1010 : Spitzer 24µm photometry of A dwarfs (Rieke+, 2005)
J/ApJS/152/261 : Chromospheric Ca II emission in nearby stars (Wright+, 2004)
J/AJ/126/2048 : NStars project: the Northern Sample. I. (Gray+, 2003)
J/ApJ/555/932 : IR fluxes of solar-type stars (Spangler+, 2001)
J/A+A/379/976 : Moving groups late-type stars EWs + fluxes (Montes+ 2001)
J/A+A/348/897 : Ages of main-sequence stars (Lachaume+, 1999)
J/MNRAS/298/332 : Chromospheric activity-age relation (Rocha-Pinto+ 1998)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- S Survey (Db=DEBRIS survey (HD sources only);
or D=DUNES survey)
4- 13 A10 --- Name Star name (HD or HIP)
14 A1 --- n_Name [*ds] Individual note on star (1)
16- 22 A7 --- SpT MK spectral type
24- 27 F4.2 Gyr Age [0.01/9.3]? Age
29- 33 I5 mJy P24 [31/13347] 24um predicted flux density for
the photosphere
35- 41 F7.2 mJy P70 [3.4/1475] 70um predicted flux density for
the photosphere
43- 48 F6.2 mJy P100 [0/702.3] 100um predicted flux density for
the photosphere
50- 53 I4 mJy F24 [42/1647]? Spitzer/MIPS 24um measured flux
density
55- 59 F5.2 mJy e_F24 [0.4/16.5]? 24um estimated measurement error (2)
61- 64 F4.2 mJy R24 [0.8/6.4]? 24um excess with only WISE W4 (22um)
available are calculated, but the MIPS 24um
field is left empty
66- 72 F7.2 mJy F70 [-16.2/1040]? Spitzer/MIPS 70um measured flux
density
74- 78 F5.2 mJy e_F70 [1.6/11.1]? 70um estimated measurement error
80- 84 F5.2 --- chi70 [-8.1/19.6]? 70um excess χ70 parameter (3)
86- 91 F6.2 mJy F100 [-18.2/863]? Herschel/PACS 100um measured flux
density
92- 93 A2 --- f_F100 [cb ] Flag(s) on F100 (4)
95- 99 F5.2 mJy e_F100 [0.8/80]? 100um estimated measurement error (5)
101-105 F5.2 mJy chi100 [-3.8/19.6]? 100um excess χ100 parameter
107 A1 --- FIR? [YN?] Far-IR excess? (Yes or No)
109 I1 --- q_Age [1/3]? Age reliability flag (6)
111-147 A37 --- r_Age Reference (see refs.dat file)
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Note (1): Flag as follows:
s = Extended source, based on the visual examination of the PACS 70
and/or 100 and/or 160 images.
d = K band data used instead of WISE W3.
* = HD 007439: Used standard colors in place of K.;
HD 061421: K magnitude derived from COBE measurements.
Note (2): Allowing for systematics, 1% photometric error was root-sum-squared
with the statistic ones at 24um (Engelbracht et al. 2007, J/PASP/119/994)
Note (3): Excess parameter χ70 (see, e.g., Bryden et al. 2006,
J/ApJ/636/1098) is: χ70=(F70-P70)/e_F70 (equation 1).
Note (4): Flag as follows:
c = PACS 70um data also available and was used for Spitzer MIPS 70um
comparison.
b = Extended source; photometry value from literature:
HD 05418 (Matthews et al. 2010A&A...518L.135M 2010A&A...518L.135M),
HD 102647 (Churcher et al. 2011MNRAS.417.1715C 2011MNRAS.417.1715C),
HD 109085 (Matthews et al. 2010A&A...518L.135M 2010A&A...518L.135M),
HD 115617 (Wyatt et al. 2012MNRAS.424.1206W 2012MNRAS.424.1206W),
HD 165908 (Kennedy et al. 2012MNRAS.421.2264K 2012MNRAS.421.2264K),
HIP 007978 (Liseau et al. 2010A&A...518L.132L 2010A&A...518L.132L),
HIP 107649 (Marshall et al. 2011A&A...529A.117M 2011A&A...529A.117M).
Note (5): Allowing for systematics, 5% photometric error was root-sum-squared
with the statistic ones when computing χ85.
Note (6): The age flag is based on the number and reliability of
independent methods yielding consistent age values.
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode Bibcode
24- 46 A23 --- Aut Author's name(s)
48- 80 A33 --- Comm Comment
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History:
From electronic version of the journal
References:
Gaspar et al. Paper I. 2012ApJ...749...14G 2012ApJ...749...14G
Gaspar et al. Paper II. 2012ApJ...754...74G 2012ApJ...754...74G
(End) Emmanuelle Perret [CDS] 21-Nov-2014