J/ApJ/742/123 Photometry and Velocity of LSPM J1112+7626 (Irwin+, 2011)
LSPM J1112+7626: detection of a 41 day M-dwarf eclipsing binary from the MEarth
transit survey.
Irwin J.M., Quinn S.N., Berta Z.K., Latham D.W., Torres G., Burke C.J.,
Charbonneau D., Dittmann J., Esquerdo G.A., Stefanik R.P., Oksanen A.,
Buchhave L.A., Nutzman P., Berlind P., Calkins M.L., Falco E.E.
<Astrophys. J., 742, 123 (2011)>
=2011ApJ...742..123I 2011ApJ...742..123I
ADC_Keywords: Binaries, eclipsing ; Photometry ; Radial velocities
Keywords: binaries: eclipsing - stars: low-mass
Abstract:
We report the detection of eclipses in LSPM J1112+7626, which we find
to be a moderately bright (IC=12.14±0.05) very low mass binary
system with an orbital period of 41.03236±0.00002 days, and
component masses M1=0.395±0.002M☉ and
M2=0.275±0.001M☉ in an eccentric (e=0.239±0.002) orbit. A
65 day out-of-eclipse modulation of approximately 2% peak-to-peak
amplitude is seen in I-band, which is probably due to rotational
modulation of photospheric spots on one of the binary components. This
paper presents the discovery and characterization of the object,
including radial velocities sufficient to determine both component
masses to better than 1% precision, and a photometric solution. We
find that the sum of the component radii, which is much better
determined than the individual radii, is inflated by 3.8+0.9-0.5%
compared to the theoretical model predictions, depending on the age
and metallicity assumed. These results demonstrate that the
difficulties in reproducing observed M-dwarf eclipsing binary radii
with theoretical models are not confined to systems with very short
orbital periods. This object promises to be a fruitful testing ground
for the hypothesized link between inflated radii in M-dwarfs and
activity.
Description:
LSPM J1112+7626 was targeted as part of routine operation of the
MEarth transit survey (Nutzman & Charbonneau 2008PASP..120..317N 2008PASP..120..317N;
Irwin et al. 2009IAUS..253...37I 2009IAUS..253...37I) during the 2009-2010 season, with
the first observations taken on UT 2009 December 2. Eclipses were
first detected on UT 2010 April 3 (this was a primary eclipse), and
subsequently confirmed on UT 2010 April 28 by observing the majority
of a secondary eclipse egress. A further eclipse (which was also a
secondary) was observed on UT 2010 June 8 with MEarth and the Clay
telescope.
High-resolution spectroscopic observations were obtained using the
TRES fiber-fed echelle spectrograph on the FLWO 1.5m Tillinghast
reflector with a resolving power of R∼44000. Observations commenced on
UT 2010 May 1, and continued until UT 2011 April 13, with 43 epochs
acquired.
Objects:
------------------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
------------------------------------------------------------------------
11 12 42.32 +76 26 56.4 LSPM J1112+7626 = FBS 1109+767 (P=41.03236)
------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 8245 Light curve data
table4.dat 40 39 Radial velocity data
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See also:
B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2013)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
I/298 : LSPM-North Catalog (Lepine+ 2005)
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
J/ApJ/736/12 : Transit light curves of GJ1214 (Berta+, 2011)
J/AJ/141/78 : Low-mass eclipsing binaries in KIC (Coughlin+, 2011)
J/AJ/141/166 : HATNet variability survey of K and M dwarfs (Hartman+, 2011)
J/ApJ/728/48 : Multicolor eclipse data for 6 new binaries (Kraus+, 2011)
J/AJ/142/160 : Kepler Mission. II. 2165 eclipsing binaries (Slawson+, 2011)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/ApJ/684/635 : New low-mass eclipsing binary from SDSS-II (Blake+, 2008)
J/MNRAS/389/585 : Fundamental parameters of M dwarfs (Casagrande+, 2008)
J/AJ/130/1680 : LSPM-North proper-motion catalog nearby stars (Lepine+, 2005)
J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/A+A/327/1039 : Structure and evolution of low-mass stars (Chabrier+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 -- Set Data-set identifier (1)
2 I1 -- Orb ? Orbit number; from zero at T0 (2)
4- 17 F14.6 d HJD Heliocentric Julian Date of mid-exposure (UTC)
19- 25 F7.4 mag mag Differential magnitude
27- 32 F6.4 mag e_mag Error in mag
34- 39 F6.3 mag dmag Frame zero point offset Δmag
41- 45 F5.2 pix FWHM FWHM of stellar images (3)
47- 52 F6.4 -- AirM Airmass
54 I1 -- Flag Field angle divided by 180 degrees (4)
56- 63 F8.3 pix x X pixel coordinate of star
65- 72 F8.3 pix y Y pixel coordinate of star
74- 80 F7.4 mag CM Common-mode differential magnitude (5)
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Note (1): Data-set as follows:
C = Clay telescope secondary eclipse (magnitudes for each
eclipse/night were separately normalized to zero median).
H = Hankasalmi primary eclipse (normalized to zero median as above).
O = MEarth out of eclipse (magnitudes in the instrumental system).
P = MEarth primary eclipse (715nm long-pass, normalized as above).
S = MEarth secondary eclipse (normalized as above).
Note (2): Given only for the data-sets containing eclipses. These are the
numbers used in the figures showing the light curves in the paper.
Note (3): Zero in cases where the FWHM could not be reliably estimated.
Note (4): Flag for detecting "meridian flip" on German equatorial mountings.
Used only for the MEarth data, where the flag is 0 when the telescope
was observing in the usual orientation for the east side and 1 for the
west side of the meridian. Note that there is not a one-to-one
relation with the sign of the hour angle because the MEarth mounts can
track approximately 5 degrees across the meridian before needing to
change sides of the pier, so this flag can sometimes be 0 even for
(small) positive hour angle.
Note (5): For the MEarth data only. Gives the "common mode" interpolated to the
Julian date of the exposure. Derived from the average differential
magnitude of all the M-dwarfs observed by all 8 MEarth telescopes in a
given time interval. This should be scaled and subtracted from "mag"
to correct for the suspected variations in the MEarth bandpass with
humidity and temperature (see text).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 12 F12.4 d HJD Heliocentric Julian Date of mid-exposure (UTC)
14- 20 F7.5 --- Phase Normalized orbital phase
22- 27 F6.2 km/s RV1 Barycentric radial velocity of star 1
29- 34 F6.2 km/s RV2 Barycentric radial velocity of star 2
36- 40 F5.3 --- Cpk Peak normalized cross-correlation from todcor (1)
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Note (1): These are later used for weighting the radial velocity points in the
solution.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Apr-2013