J/AJ/157/202 IRAC fluxes of the ID8 and P1121 systems (Su+, 2019)
Extreme debris disk variability: exploring the diverse outcomes of large
asteroid impacts during the era of terrestrial planet formation.
Su K.Y.L., Jackson A.P., Gaspar A., Rieke G.H., Dong R., Olofsson J.,
Kennedy G.M., Leinhardt Z.M., Malhotra R., Hammer M., Meng H.Y.A.,
Rujopakarn W., Rodriguez J.E., Pepper J., Reichart D.E., James D.,
Stassun K.G.
<Astron. J., 157, 202 (2019)>
=2019AJ....157..202S 2019AJ....157..202S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, G-type ; Photometry, infrared
Keywords: circumstellar matter - infrared: planetary systems -
planets and satellites: dynamical evolution and stability -
stars: individual (2MASS J08090250-4858172, 2MASS J07354269-1450422)
Abstract:
The most dramatic phases of terrestrial planet formation are thought
to be oligarchic and chaotic growth, on timescales of up to 100-200 Myr,
when violent impacts occur between large planetesimals of sizes up to
protoplanets. Such events are marked by the production of large amounts
of debris, as has been observed in some exceptionally bright and young
debris disks (termed extreme debris disks). Here we report five years
of Spitzer measurements of such systems around two young solar-type
stars: ID8 and P1121. The short-term (weekly to monthly) and long-term
(yearly) disk variability is consistent with the aftermaths of large
impacts involving large asteroid-sized bodies. We demonstrate that an
impact-produced clump of optically thick dust, under the influence of
the dynamical and viewing geometry effects, can produce short-term
modulation in the disk light curves. The long-term disk flux variation
is related to the collisional evolution within the impact-produced
fragments once released into a circumstellar orbit. The time-variable
behavior observed in the P1121 system is consistent with a hypervelocity
impact prior to 2012 that produced vapor condensates as the dominant
impact product. Two distinct short-term modulations in the ID8 system
suggest two violent impacts at different times and locations. Its
long-term variation is consistent with the collisional evolution of two
different populations of impact-produced debris dominated by either vapor
condensates or escaping boulders. The bright, variable emission from
the dust produced in large impacts from extreme debris disks provides
a unique opportunity to study violent events during the era of
terrestrial planet formation.
Description:
Spitzer/IRAC observations were obtained under GO programs PID 10157
(PI Rieke) and PID 11093, 13014 (PI Su). ID8 was monitored with daily
cadence under program PID 10157 from 2014 June to August, resulting in
a total of 59 sets of observations in 2014. Both ID8 and P1121 were
monitored under PID 11093 and 13014 with a cadence of about three days
during their visibility windows from 2015 to 2017, resulting in a total
of 220 sets of observations for ID8 and a total of 93 sets of observations
for P1121. For both objects, we used a frame time of 30 s with 10 cycling
dithers (i.e., 10 frames per Astronomical Observation Request (AOR))
to minimize the intrapixel sensitivity variations of the detector
(Reach et al. 2005PASP..117..978R 2005PASP..117..978R) at both [3.6] and [4.5], achieving
a signal-to-noise ratio (S/N)>100 in single-frame photometry. These data
were processed with the IRAC pipeline S19.2.0 by the Spitzer Science
Center.
Objects:
-------------------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------------------
08 09 02.51 -48 58 17.3 ID8 = 2MASS J08090250-4858172
07 35 42.69 -14 50 42.2 P1121 = 2MASS J07354269-1450422
-------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . this file
table1.dat 74 421 The IRAC fluxes of the ID8 system
table2.dat 74 114 The IRAC fluxes of the P1121 system
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See also:
J/ApJ/636/1098 : Debris disks around solar-type stars (Bryden+, 2006)
J/ApJ/705/89 : IRS spectra of solar-type stars (Lawler+, 2009)
J/ApJS/211/25 : Spitzer/IRS debris disk catalog. I. (Chen+, 2014)
J/ApJ/798/87 : Spitzer/IRS debris disk catalog. II. (Mittal+, 2015)
J/ApJ/805/77 : Spitzer 3.6 and 4.5um monitoring of 5 stars (Meng+, 2015)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- AOR [45677056/61677824] Spitzer Astronomical
Observation Request (AOR) key
10- 20 F11.5 d BMJD3.6 [56072.71322/58018.37332]? Barycentric Modified
Julian Date of the 3.6 micron observation
22- 26 F5.2 mJy F3.6 [9.31/11.93]? Spitzer/IRAC 3.6 micron band flux
density
28- 31 F4.2 mJy e_F3.6 [0.01/0.13]? Uncertainty in F3.6
33- 36 F4.2 mJy exF3.6 [0.47/3.37]? Excess 3.6 micron flux density (1)
38- 41 F4.2 mJy e_exF3.6 [0.13/0.19]? Uncertainty in exF3.6
43- 53 F11.5 d BMJD4.5 [56072.70783/58018.36796] Barycentric Modified
Julian Date of the 4.5 micron observation
55- 59 F5.2 mJy F4.5 [6.91/10.47] Spitzer/IRAC 4.5 micron band flux
density
61- 64 F4.2 mJy e_F4.5 [0.01/0.33] Uncertainty in F4.5
66- 69 F4.2 mJy exF4.5 [0.74/4.84] Excess 4.5 micron flux density (1)
71- 74 F4.2 mJy e_exF4.5 [0.09/0.35] Uncertainty in exF4.5
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Note (1): Excluding the star.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 06-Aug-2019