J/AJ/156/286 The LEECH exoplanet imaging survey (Stone+, 2018)
The LEECH exoplanet imaging survey: limits on planet occurrence rates under
conservative assumptions.
Stone J.M., Skemer A.J., Hinz P.M., Bonavita M., Kratter K.M., Maire A.-L.,
Defrere D., Bailey V.P., Spalding E., Leisenring J.M., Desidera S.,
Bonnefoy M., Biller B., Woodward C.E., Henning T., Skrutskie M.F.,
Eisner J.A., Crepp J.R., Patience J., Weigelt G., De Rosa R.J.,
Schlieder J., Brandner W., Apai D., Su K., Ertel S., Ward-Duong K.,
Morzinski K.M., Schertl D., Hofmann K.-H., Close L.M., Brems S.S.,
Fortney J.J., Oza A., Buenzli E., Bass B.
<Astron. J., 156, 286-286 (2018)>
=2018AJ....156..286S 2018AJ....156..286S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Interferometry ; Stars, distances ;
Photometry, infrared ; Spectral types ; Stars, ages ;
Stars, masses ; Abundances ; Stars, diameters ; Surveys
Keywords: planetary systems - planets and satellites: gaseous planets -
stars: imaging - techniques: high angular resolution
Abstract:
We present the results of the largest L' (3.8 µm) direct imaging survey
for exoplanets to date, the Large Binocular Telescope Interferometer
Exozodi Exoplanet Common Hunt (LEECH). We observed 98 stars with spectral
types from B to M. Cool planets emit a larger share of their flux in L'
compared to shorter wavelengths, affording LEECH an advantage in detecting
low-mass, old, and cold-start giant planets. We emphasize proximity over
youth in our target selection, probing physical separations smaller than
other direct imaging surveys. For FGK stars, LEECH outperforms many previous
studies, placing tighter constraints on the hot-start planet occurrence
frequency interior to ∼20 au. For less luminous, cold-start planets, LEECH
provides the best constraints on giant-planet frequency interior to ∼20 au
around FGK stars. Direct imaging survey results depend sensitively on both
the choice of evolutionary model (e.g., hot- or cold-start) and assumptions
(explicit or implicit) about the shape of the underlying planet
distribution, in particular its radial extent. Artificially low limits
on the planet occurrence frequency can be derived when the shape of the
planet distribution is assumed to extend to very large separations, well
beyond typical protoplanetary dust-disk radii (~<50 au), and when hot-start
models are used exclusively. We place a conservative upper limit on the
planet occurrence frequency using cold-start models and planetary
population distributions that do not extend beyond typical protoplanetary
dust-disk radii. We find that ~<90% of FGK systems can host a 7-10 MJup
planet from 5 to 50 au. This limit leaves open the possibility that planets
in this range are common.
Description:
Our survey was conducted using the LBTI instrument (Hinz et al.
2016SPIE.9907E..04H 2016SPIE.9907E..04H) at the LBT on Mt. Graham in southern Arizona. LBTI is
located between the two 8.4 m primary mirrors of the LBT at the combined
bent Gregorian focus. Light from each side of the telescope is corrected
for atmospheric aberrations using the LBTI AO system (Bailey et al.
2014SPIE.9148E..03B 2014SPIE.9148E..03B) and delivered into the instrument via a cryogenic
beam combiner where it is then directed to individual science modules.
For LEECH observations, we used the LMIRcam module of LBTI, which is
optimized for work in the thermal-infrared (3-5 µm; Skrutskie et al.
2010SPIE.7735E..3HS; Leisenring et al. 2012SPIE.8446E..4FL). LBTI does not
include an instrument derotator, so images always rotate with respect to
the detector pixels as the parallactic angle changes. During the course of
the LEECH survey, LMIRcam provided an 11"x11" field of view, reading a
1024x1024 subsection of its 5.2 µm cutoff HAWAII-2RG detector (the full
2048x2048 extent of the array now provides a 20"x20" field of view with
LMIRcam). LMIRcam was designed with a plate scale to accommodate imaging
interferometry at the full resolution of the 23 m LBT (10.7 mas/pixel).
However, for LEECH observations, we operated without overlapping and
interfering the beams of the two primary mirrors, opting to make two images
of each source on the detector instead. In this mode, the L' images from
each side were oversampled, providing added robustness to bad pixels
and cosmic rays.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 103 98 Target summary
table3.dat 85 35 Best-fit age, mass, and metallicity for observed
stars in the Field-B/A sublist
table4.dat 48 115 LEECH observing log
table6.dat 102 26 Summary of binary system parameters
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See also:
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/PASP/122/162 : Direct imaging of exoplanets (Beichman+, 2010)
J/ApJ/768/2 : Spitzer and Herschel observations of debris disks
(Gaspar+, 2013)
J/A+A/591/A84 : Search for UMa group companions (Ammler-von Eiff+, 2016)
J/AJ/156/137 : Wide-orbit Exoplanet search with IR Direct imaging
(Baron+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Target name
12- 14 A3 --- n_Name Note on Name (1)
16- 35 A20 --- OName Other name
37- 38 I2 h RAh Hour of Right Ascension (J2000)
40- 41 I2 min RAm Minute of Right Ascension (J2000)
43- 44 I2 s RAs Second of Right Ascension (J2000)
46 A1 --- DE- Sign of the Declination (J2000)
47- 48 I2 deg DEd Degree of Declination (J2000)
50- 51 I2 arcmin DEm Arcminute of Declination (J2000)
53- 54 I2 arcsec DEs Arcsecond of Declination (J2000)
56- 60 F5.2 pc Dist [3.2/78.25] Distance
62- 66 F5.2 mag Vmag [0.03/10.17] V band magnitude
68- 71 F4.2 mag Kmag [0.13/6.88]? K band magnitude
73- 80 A8 --- SpType Spectral type
82- 85 F4.2 mag Lmag [0.13/6.77] L' band magnitude (2)
87- 90 I4 Myr Age [10/1650] Age (3)
92- 95 F4.2 Msun Mass [0.4/4.07] Stellar mass (4)
97-103 A7 --- Sublist Target sublist (5)
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Note (1): Note as follows:
b = Our photometric sensitivity was sufficient to detect =<10 MJup
cold-start planets in this system;
c = Close (~<1") binary system;
d = Wide (≳1") binary system.
Note (2): Magnitudes in the L'-band were derived using the K-L' or V-L' color
spectral-type relations of Bessell & Brett (1988PASP..100.1134B 1988PASP..100.1134B).
Note (3): Stellar ages for stars in the FGK subsample are from
Mamajek & Hillenbrand (2008, J/ApJ/687/1264) and Heinze et al.
(2010ApJ...714.1551H 2010ApJ...714.1551H). Ages for stars in the Dusty-A/F subsample are from
Gaspar et al. (2013, J/ApJ/768/25). Ages for stars in the UMa subsample are
from Jones et al. (2015ApJ...813...58J 2015ApJ...813...58J). Ages for stars in the Field-B/A
subsample are derived in this work.
Note (4): Stellar masses were derived by fitting to PARSEC isochrones
(Marigo et al. 2017ApJ...835...77M 2017ApJ...835...77M) using the target age and photometry,
except for the Field-B/A sublist for which mass and age were fit
simultaneously (see Section 2.2).
Note (5): We compiled a master target list comprising four sublists for use
during the LEECH survey. Each sublist carried a slightly different emphasis,
though the guiding principles for each were relative proximity and age
~<1 Gyr. The four sublists are defined as follows:
FGK = Emphasizes proximity and F/G/K spectral type. Targets for this FGK
sublist were drawn from Heinze et al. (2010ApJ...714.1570H 2010ApJ...714.1570H) and
Mamajek & Hillenbrand (2008, J/ApJ/687/1264);
UMa = Stars in the Ursa Major moving group selected from King et al.
(2003AJ....125.1980K 2003AJ....125.1980K). This sublist provides a set of targets,
with spectral types ranging from A to M, that all have the same
well-constrained age (414±23 Myr; Jones et al.
2015ApJ...813...58J 2015ApJ...813...58J);
Dusty-A/F = Includes A- and F-type stars that show evidence of a debris disk,
drawn from Gaspar et al. (2013, J/ApJ/768/25);
Field-A/B = Includes B- and A-type field stars with estimated ages ~<1 Gyr
(see Section 2.2).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 15 I4 Myr Age [50/1646] Best-fit age
17- 20 I4 Myr b_Age16-84 [14/1249] Lower value of age in the
interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
22- 25 I4 Myr B_Age16-84 [81/1723] Upper value of age in the
interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
27- 30 I4 Myr b_Age2.5-97.5 [7/1045] Lower value of age in the
interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
32- 35 I4 Myr B_Age2.5-97.5 [124/5477] Upper value of age in the
interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
37- 39 F3.1 Msun Mass [1.5/4.5] Best-fit mass
41- 43 F3.1 Msun b_Mass16-84 [1.4/4.4] Lower value of mass in the
interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
45- 47 F3.1 Msun B_Mass16-84 [1.5/4.5] Upper value of mass in the
interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
49- 51 F3.1 Msun b_Mass2.5-97.5 [1.4/4.3] Lower value of mass in the
interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
53- 55 F3.1 Msun B_Mass2.5-97.5 [1.5/4.5] Upper value of mass in the
interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
57- 61 F5.2 [Sun] logZ [-0.26/0.04] Best-fit metallicity
log10(Z/Z☉)
63- 67 F5.2 [Sun] b_logZ16-84 [-0.27/-0.11] Lower value of metallicity in
the interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
69- 73 F5.2 [Sun] B_logZ16-84 [-0.13/0.09] Upper value of metallicity in
the interval between 16% and 84% in the
cumulative distribution function of
the posterior probability distribution
75- 79 F5.2 [Sun] b_logZ2.5-97.5 [-0.3/-0.17] Lower value of metallicity in
the interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
81- 85 F5.2 [Sun] B_logZ2.5-97.5 [-0.04/0.19] Upper value of metallicity in
the interval between 2.5% and 97.5% in the
cumulative distribution function of
the posterior probability distribution
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12- 22 A11 "date" Date Observation date
24- 26 F3.1 arcsec Seeing [0.6/2.1] Mean seeing (1)
28- 30 F3.1 arcsec e_Seeing [0/0.7]? Standard deviation of the seeing (1)
32- 35 I4 s Tint-l [10/4794]? Exposure time with the left side
of LBT
37- 39 I3 deg Rot-l [0/169]? Rotation angle with the left side of
LBT
41- 44 I4 s Tint-r [105/6675]? Exposure time with the right side
of LBT
46- 48 I3 deg Rot-r [3/170]? Rotation angle with the right side of
LBT
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Note (1): Mean and standard deviation of the seeing as measured by the DIMM at
LBT and recorded in image headers. For some data sets, seeing was unavailable
in headers. For these we report the value written in the nightly observing
log.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
12 A1 --- n_Name [d] Note on Name (1)
14- 17 F4.2 Msun M1 [0.85/3.48] Mass of the primary
19- 22 F4.2 Msun M2 [0.3/2.7]? Mass of the secondary
24- 27 F4.2 --- M2/M1 [0.09/1] Mass ratio (2)
29- 33 F5.3 arcsec Sep [0.003/8]? Separation
35- 38 F4.2 --- e [0/0.92]? Eccentricity
40- 44 F5.1 AU acrit-cs [5.9/109.7]? Circumstellar critical radius
acritcs (3)
46- 51 F6.2 AU acrit-cb [0.06/972] Circumbinary critical radius
acritcb (4)
53- 59 F7.2 d Per [4.02/1202.2]? Period
61- 82 A22 --- r_acrit Reference for acrit
84-102 A19 --- Bibcode Bibcode of the reference
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Note (1): Note as follows:
d = These targets include some restricted parameter space in the LEECH
sensitivity maps.
Note (2): We conservatively assume a mass ratio of 1 when there is no constraint
on the secondary mass. This maximizes the excluded parameter space.
Note (3): Planets are dynamically excluded on orbits with larger semimajor axes,
following Holman & Wiegert (1999AJ....117..621H 1999AJ....117..621H).
Note (4): Planets are dynamically excluded on orbits with smaller semimajor
axes, following Holman & Wiegert (1999AJ....117..621H 1999AJ....117..621H).
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 24-Apr-2019