J/ApJ/718/1353 Light curve of the triple system NLTT 41135 (Irwin+, 2010)
NLTT 41135: a field M dwarf + brown dwarf eclipsing binary in a triple system,
discovered by the MEarth observatory.
Irwin J., Buchhave L., Berta Z.K., Charbonneau D., Latham D.W., Burke C.J.,
Esquerdo G.A., Everett M.E., Holman M.J., Nutzman P., Berlind P.,
Calkins M.L., Falco E.E., Winn J.N., Johnson J.A., Gazak J.Z.
<Astrophys. J., 718, 1353-1366 (2010)>
=2010ApJ...718.1353I 2010ApJ...718.1353I
ADC_Keywords: Stars, double and multiple ; Photometry
Keywords: binaries: eclipsing - brown dwarfs - stars: individual (NLTT 41135) -
stars: low-mass
Abstract:
We report the discovery of an eclipsing companion to NLTT 41135, a
nearby M5 dwarf that was already known to have a wider, slightly more
massive common proper motion companion, NLTT 41136, at 2.4"
separation. Analysis of combined-light and RV curves of the system
indicates that NLTT 41135B is a (31-34)±3MJup brown dwarf (where
the range depends on the unknown metallicity of the host star) on a
circular orbit. The visual M dwarf pair appears to be physically
bound, so the system forms a hierarchical triple, with masses
approximately in the ratio 8:6:1. The eclipses are grazing, preventing
an unambiguous measurement of the secondary radius, but follow-up
observations of the secondary eclipse (e.g., with the James Webb Space
Telescope) could permit measurements of the surface brightness ratio
between the two objects, and thus place constraints on models of brown
dwarfs.
Description:
Eclipses in NLTT 41135 were initially detected from data taken during
2009 February to May (inclusive) as part of routine operation of the
MEarth observatory. We immediately switched to a follow-up mode after
the initial detection, observing the object at the highest possible
cadence (approximately 3 minutes including overheads) during the night
of UT 2009 May 25 when an eclipse was predicted to occur.
In order to determine the flux ratio of the M dwarf pair, and hence
the intrinsic flux decrement during eclipse, we obtained a single,
resolved image of the system using the Orthogonal Parallel Transfer
Imaging Camera (OPTIC) on the University of Hawaii 2.2m telescope,
during the night of UT 2009 June 9 (Table 1).
Observations centered around the primary eclipse of UT 2009 June 20
were obtained using the KeplerCam instrument on the Fred Lawrence
Whipple Observatory (FLWO) 1.2m telescope (Table 2).
Objects:
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RA (2000) DE Designation(s)
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15 46 04.26 +04 41 30.0 NLTT 41135 = WDS J15461+0441B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 196 UH 2.2m resolved z-band light curve
table2.dat 68 63 FLWO 1.2m z-band light curve
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2012)
I/298 : LSPM-North Catalog (Lepine+ 2005)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d HJD Heliocentric Julian Date of mid-exposure in
UTC time-system
16- 22 F7.4 mag zmag Differential z-band magnitude
24- 29 F6.4 mag e_zmag Error in zmag (1)
31- 36 F6.3 mag Dmag Frame zero point offset (2)
38- 42 F5.2 pix FWHM FWHM of stellar images (3)
44- 50 F7.5 -- Airmass Airmass
52- 59 F8.3 pix x X pixel coordinate of star (4)
61- 68 F8.3 pix y Y pixel coordinate of star (4)
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Note (1): Estimated using a standard CCD noise model, including contributions
from Poisson noise in the stellar counts, sky noise, readout noise
and errors in the sky background estimation.
Note (2): Correction to the frame magnitude zero-point applied by the
differential photometry procedure. More negative numbers indicate
greater losses. Please note that this has already been applied to the
zmag column and is provided only for reference (e.g. distinguishing
frames with large losses due to cloud).
Note (3): The plate scale was 0.14"/pixels for the UH 2.2m and 0.67"/pixels for
the FLWO 1.2m.
Note (4): On the CCD image and derived using a standard intensity-weighted
moments analysis.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Jun-2012