J/AJ/145/66 Spitzer light curves of YSOs in IC 348 (Flaherty+, 2013)
Kinks and dents in protoplanetary disks: rapid infrared variability as evidence
for large structural perturbations.
Flaherty K.M., Muzerolle J., Rieke G., Gutermuth R., Balog Z., Herbst W.,
Megeath S.T.
<Astron. J., 145, 66 (2013)>
=2013AJ....145...66F 2013AJ....145...66F
ADC_Keywords: Clusters, open ; YSOs ; Photometry, infrared ; Equivalent widths ;
Effective temperatures
Keywords: accretion, accretion disks - stars: formation - stars: protostars -
stars: pre-main sequence - stars: variables: T Tauri, Herbig Ae/Be
Abstract:
We report on synoptic observations at 3.6 and 4.5µm of young
stellar objects in IC 348 with 38epochs covering 40days. We find that
among the detected cluster members, 338 at [3.6] and 269 at both [3.6]
and [4.5], many are variable on daily to weekly timescales with
typical fluctuations of ∼0.1mag. The fraction of variables ranges from
20% for the diskless pre-main sequence stars to 60% for the stars
still surrounded by infalling envelopes. We also find that stars in
the exposed cluster core are less variable than the stars in the
dense, slightly younger, southwestern ridge. This trend persists even
after accounting for the underlying correlation with infrared spectral
energy distribution type, suggesting that the change in variable
fraction is not simply a reflection of the change in relative fraction
of class I versus class II sources across the cloud, but instead
reflects a change in variability with age. We also see a strong
correlation between infrared variability and X-ray luminosity among
the class II sources. The observed variability most likely reflects
large changes in the structure of the inner wall located at the dust
sublimation radius. We explore the possibility that these structural
perturbations could be caused by a hot spot on the star heating dust
above the sublimation temperature, causing it to evaporate rapidly,
and increasing the inner radius for a portion of the disk. Under a
number of simplifying assumptions we show that this model can
reproduce the size and timescale of the 3.6 and 4.5µm fluctuations.
Regardless of its source, the infrared variability indicates that the
inner disk is not a slowly evolving entity, but instead is a bubbling,
warped, dented mass of gas and dust whose global size and shape
fluctuate in a matter of days.
Description:
Our cluster membership has been compiled from Luhman et al. (2003,
cat. J/ApJ/593/1093); Lada et al. (2006, cat. J/AJ/131/1574); Muench
et al. (2007, cat. J/AJ/134/411); Muzerolle et al.
(2006ApJ...643.1003M 2006ApJ...643.1003M); Luhman et al. (2005ApJ...618..810L 2005ApJ...618..810L).
We performed repeated IRAC 3.6 and 4.5µm observations (PID 60160)
of IC 348 over the course of 40days from 2009 October 3 to November 7.
The cadence of these observations was varied from once every four
hours to once every two days to capture a wide range of possible
timescales for the variability. We mapped the cluster with a 5 by 5
grid, with each grid point separated by 260" and the total field
centered at 03:44:20 +32:03:01.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 114 377 Cluster member properties
table2.dat 47 14326 [3.6] photometry
table3.dat 47 14326 [4.5] photometry
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See also:
II/197 : ISM towards IC 348 and Per OB2 (Cernis, 1993)
J/other/Nat/493.378 : LRL 54361 Spitzer light curves (Muzerolle+, 2013)
J/A+A/539/A64 : X-ray data for IC 348 young stars (Alexander+, 2012)
J/ApJS/201/11 : Mid-IR spectral variability atlas of YSOs (Kospal+, 2012)
J/A+A/537/A135 : X-ray view of IC348 (Stelzer+, 2012)
J/ApJ/733/50 : Mid-IR photometric monitoring of the ONC
(Morales-Calderon+, 2011)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/138/703 : Deep MIPS observations of IC 348 nebula (Currie+, 2009)
J/AJ/134/411 : Properties of IC 348 members (Muench+, 2007)
J/ApJ/649/862 : IR phot. of IC 348 pre-main-sequence stars (Cieza+, 2006)
J/AJ/131/1574 : Infrared photometry of IC348 members (Lada+, 2006)
J/ApJ/646/297 : Pre-main-sequence stars spitzer observations (Rebull+, 2006)
J/MNRAS/358/341 : Ic photometry of IC 348 (Littlefair+, 2005)
J/AJ/127/1602 : Cousins RI photometry in IC 348 (Cohen+, 2004)
J/ApJ/593/1093 : IC 348 membership (Luhman+, 2003)
J/ApJ/597/555 : IR photometry of IC 348 young brown dwarfs (Mainzer+, 2003)
J/A+A/409/147 : J magnitude of IC 348 brown dwarfs (Preibisch+, 2003)
J/AJ/122/866 : X-ray sources in IC 348 from Chandra (Preibisch+, 2001)
J/ApJ/541/977 : HST observations of low-mass stars in IC 348 (Najita+, 2000)
J/ApJ/525/466 : Young low-mass stars & brown dwarfs in IC 348 (Luhman+, 1999)
J/ApJ/497/736 : The young cluster IC 348. (Herbig, 1998)
J/A+A/324/549 : Deep UVBRI photometry in IC 348 (Trullols+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- LRL [1/57025] YSO identifier (G1)
6 A1 --- m_LRL [AB] Multiplicity flag on LRL (A or B)
8- 14 F7.4 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 22 F7.4 deg DEdeg Declination in decimal degrees (J2000)
24- 28 I5 K Teff ?=-100.000 Effective temperature
30- 37 F8.3 Lsun Lum ?=-100.000 Stellar luminosity
39- 43 F5.1 0.1nm W(Ha) ?=-10.0 Hα equivalent width; in Å (1)
44- 45 A2 --- --- [00]
47- 53 F7.3 d Per ?=-10.000 Optical period (2)
55- 60 F6.3 mag AV The V-band extinction
62- 67 F6.1 ZW LX ?=-10.0 X-ray luminosity; in 1028erg/s (3)
68- 69 A2 --- --- [00]
71- 77 F7.3 mag E3.6 ?=-10.000 Excess emission at 3.6µm
79- 85 F7.2 --- alpha ?=-100.00 Slope of the observed infrared SED (4)
87- 93 F7.2 --- alpha2 ?=-100.00 Slope of the dereddened infrared
SED (5)
95- 99 F5.2 arcmin Dist Distance from HH 211 (6)
101-102 A2 --- f_LRL Variable? (y, n, y1, n1, p, or b) (7)
104-114 A11 --- Ref Reference (8)
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Note (1): Here we actually report the negative of the Hα equivalent width,
with positive numbers corresponding to emission. Hα equivalent width
is not reported when it is in absorption.
Note (2): Optical period is taken from Cohen et al. (2004, cat. J/AJ/127/1602),
Cieza & Baliber (2006, cat. J/ApJ/649/862) and references therein. Values
of 0 correspond to stars that were detected in these surveys, but no period
structure was detected.
Note (3): From Preibisch & Zinnecker (2002AJ....123.1613P 2002AJ....123.1613P).
Note (4): Defined as λFλ∝λα over the
IRAC (3-8µm) wavelengths.
Note (5): Unless otherwise stated, this is the value of the infrared SED that
is used in the text.
Note (6): IC 348 is composed of an exposed cluster core in the northeast and a
highly obscured region in the southwest where most of the younger class I
sources, along with all of the molecular outflows and submillimeter cores,
reside. The presence of these less-evolved sources indicates that the
southwestern ridge is a region of very recent star formation. We
characterize the position as the distance from HH 211, a prominent
Herbig-Haro object in this region.
Note (7): Multiplicity flag on Name as follows:
y = Variable;
n = Not variable;
y1 = Variable, but only detected at [3.6];
n1 = Not variable, but only detected at [3.6];
p = Periodic;
b = A nearby source prevents us from accurately assessing variability;
blank = Source was not detected.
Note (8): Reference as follows:
luh03 = Luhman et al. (2003, cat. J/ApJ/593/1093);
mue07 = Muench et al. (2007, cat. J/AJ/134/411);
lad06 = Lada et al. (2006, cat. J/AJ/131/1574);
muz06 = Muzerolle et al. (2006ApJ...643.1003M 2006ApJ...643.1003M);
luh05 = Luhman et al. (2005ApJ...618..810L 2005ApJ...618..810L).
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- LRL [1/57025] YSO identifier (G1)
6 A1 --- m_LRL [AB] Multiplicity flag on LRL (A or B)
8- 14 F7.4 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 22 F7.4 deg DEdeg Declination in decimal degrees (J2000)
24- 30 F7.1 d MJD [55106.9/55142.1] Modified Julian Date
32- 39 F8.3 mag [3.6] ?=-100.000 Spitzer/IRAC 3.6µm band magnitude
41- 47 F7.4 mag e_[3.6] ?=10.0000 Uncertainty in [3.6]
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- LRL [1/57025] YSO identifier (G1)
6 A1 --- m_LRL [AB] Multiplicity flag on LRL (A or B)
8- 14 F7.4 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 22 F7.4 deg DEdeg Declination in decimal degrees (J2000)
24- 30 F7.1 d MJD [55106.9/55142.1] Modified Julian Date
32- 39 F8.3 mag [4.5] ?=-100.000 Spitzer/IRAC 4.5µm band magnitude
41- 47 F7.4 mag e_[4.5] ?=10.0000 Uncertainty in [4.5]
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Global notes:
Note (G1): Sequential running number for Young Stellar Objects (YSOs) in IC 348
as listed in literature (Luhman et al., 1998ApJ...508..347L 1998ApJ...508..347L number).
<Cl* IC 348 LRL NNNNNA> in Simbad.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 02-Apr-2014