J/AJ/170/26 Predicted detections of exoplanets using CHES & HWO (Bao+, 2025)
Closeby Habitable Exoplanet Survey (CHES).
IV. Synergy between astrometry and direct imaging missions of the Habitable
World Observatory for detecting Earth-like planets.
Bao C., Ji J., Tan D., Chen G., Huang X., Wang Su, Dong Y.
<Astron. J., 170, 26 (2025)>
=2025AJ....170...26B 2025AJ....170...26B
ADC_Keywords: Exoplanets; Positional data; Optical; Infrared; Ultraviolet
Keywords: Exoplanet detection methods ; Astrometric exoplanet detection ;
Direct imaging
Abstract:
The detection and characterization of habitable planets around nearby
stars persist as some of the foremost objectives in contemporary
astrophysics. This work investigates the synergistic integration of
astrometric and direct imaging techniques by capitalizing on the
complementary capabilities of the Closeby Habitable Exoplanet Survey
(CHES) and Habitable Worlds Observatory (HWO). Planetary brightness
and position vary over time due to phase effects and orbital
architecture, information that can be precisely provided by CHES's
astrometric measurements. By combining the precise orbital constraints
from CHES with the imaging capabilities of HWO, we evaluate the
improvements in detection efficiency, signal-to-noise ratio, and
overall planet yield. Completeness is quantified as the fraction of
injected planets that are successfully detected, while yields are
estimated for various scenarios using terrestrial planet occurrence
rates derived from the Kepler data set. Our results indicate that
prior astrometric data significantly enhance detection efficiency.
Under the adopted detection limit, our analysis indicates that prior
CHES observations can increase completeness by approximately 10% and
improve detection efficiency by factors ranging from 2 to 30. The
findings underscore the importance of interdisciplinary approaches in
the search for and characterization of habitable worlds.
Description:
The Closeby Habitable Exoplanet Survey (CHES) is a proposed mission
specifically designed to discover terrestrial planets within the
habitable zones of approximately 100 nearby solar-type stars. The CHES
satellite carries a 1.2m aperture telescope and 81 scientific CMOS
detectors delivering high stability and ultralow distortion. The
astrometric wobble of host stars, induced by Earth-mass planets in 1AU
orbits, will be measured with an expected amplitude of about 0.3uas
for a solar-mass star at 10pc. CHES allocates about 4100 hr for
additional observations, such as nearby HWO targets or compact
objects.
The Habitable Worlds Observatory (HWO) builds upon and integrates
concepts from NASA's earlier mission studies, the Habitable Exoplanet
Observatory (HabEx) and the Large Ultraviolet Optical Infrared
Surveyor (LUVOIR), and is scheduled for launch in the 2040s. HWO is a
large infrared/optical/ultraviolet space telescope which prioritizes
the detection and characterization of potentially habitable planets
around nearby stars and the search for biosignatures, using an ∼6m
space telescope equipped with advanced starlight suppression
technologies, preferentially employing a coronagraph, with a potential
starshade as a backup plan.
While HWO's final target list is yet to be determined, we adopt the
catalog filtered from ∼13,000 nearby stars from Tuchow+2024
(J/AJ/167/139), which has also been utilized by Mamajek+2024 and
Harada+2024 (J/ApJS/272/30). The HWO catalog includes 164 most
accessible main-sequence stars, comprising 66 F-type stars, 55 G-type
stars, 40 K-type stars, and three M-type stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 64 164 Results of terrestrial planets for HWO targets
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See also:
III/135A : Henry Draper Catalogue and Extension (Cannon+ 1918-1924; ADC 1989)
J/A+AS/127/1 : 1997 reference of diffuse night sky brightness (Leinert+ 1998)
J/AJ/149/131 : Parameters of galactic nearby main-sequence stars (Eker+, 2015)
J/AJ/158/109 : Occurrence rates of planets orbiting FGK stars (Hsu+, 2019)
J/AJ/161/36 : 117 exoplanets in habitable zone with Kepler DR25 (Bryson+, 2021)
J/ApJS/272/30 : Habitable Worlds Observatory (HWO): 164 targets (Harada+, 2024)
J/AJ/167/139 : HPIC catalog & potential contaminants from Gaia (Tuchow+, 2024)
J/PASP/137/J4402 : HWO Target Stars & Systems 2025 list (TSS25) (Tuchow+, 2025)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- HD HD identifier of the source (III/135A)
13- 18 F6.2 % Comp-Im [46.76/100] Completeness from direct
imaging alone
(ImagingAloneCompleteness) (1)
20- 23 F4.2 --- BtC-Im [0.28/7.78] Benefit-to-Cost from
direct imaging alone
(ImagingAloneBenefittoCost) (3)
25- 28 F4.2 --- lowYields-Im [0.11/0.38] Lower bound on the yield
from direct imaging alone
(ImagingAloneYields) (2)
30- 33 F4.2 --- upYields-Im [0.16/0.78] Upper bound on the yield
from direct imaging alone
(ImagingAloneYields) (2)
35- 40 F6.2 % Comp-ImAst [70.27/100] Completeness from direct
imaging and astrometric data
(ImagingAstrometryCompleteness) (1)
42- 47 F6.2 --- BtC-ImAst [2.22/213.09] Benefit-to-Cost from
direct imaging and astrometric data
(ImagingAstrometryBenefittoCost)
(3)
49- 52 F4.2 --- lowYields-ImAst [0.14/0.4] Lower bound on the yield
from direct imaging and astrometric
data (ImagingAstrometryYields) (2)
54- 57 F4.2 --- upYields-ImAst [0.21/0.84] Upper bound on the yield
from direct imaging and astrometric
data (ImagingAstrometryYields) (2)
59- 64 F6.2 % Priority [37.29/100] Target priority (4)
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Note (1): The completeness is the fraction of injected planets that are
successfully detected. See Section 5.
Note (2): The yields are the estimated number of planets located in the
conservative habitable zone ("HZ"), and the lower (upper) bounds of yields
are based on low (high) occurrence rate model. See Section 5.
Note (3): The Benefit-to-Cost ratio corresponds to the detection efficiency.
See Section 5.
Note (4): The priority is calculated based on :
rankindex = Comp-ImAst x BtC-ImAst x Yields-ImAst
We also adopt the classification of Mamajek+2024 (2024arXiv240212414M 2024arXiv240212414M) for
targets with an existing disk or a companion star; we multiply the rank
index by 0.5 accordingly. For targets with known planets or candidates, we
multiply the rank index by 2.
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History:
From electronic version of the journal
References:
Bao et al. Paper I 2024AJ....167..286B 2024AJ....167..286B
Tan et al. Paper II 2024AJ....168..172T 2024AJ....168..172T
Huang et al. Paper III 2025ApJ...984...82H 2025ApJ...984...82H
Bao et al. Paper IV This catalog
(End) Prepared by [AAS], Robin Leichtnam [CDS] 31-Mar-2026