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Kepler-160
Kepler-160
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Kepler-160
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra[1]
Right ascension 19h 11m 05.6526s[2]
Declination +42° 52′ 09.473″[2]
Apparent magnitude (V) 13.101
Characteristics
Evolutionary stage G2V
J−H color index 0.359
J−K color index 0.408
Variable type ROT, Planetary transit
Astrometry
Proper motion (μ) RA: 3.477(16) mas/yr[2]
Dec.: −5.233(19) mas/yr[2]
Parallax (π)1.0644±0.0154 mas[2]
Distance3,060 ± 40 ly
(940 ± 10 pc)
Details
Radius1.118+0.015
−0.045
[3] R
Luminosity1.01±0.05[3] L
Surface gravity (log g)4.515[4] cgs
Temperature5471+115
−37
[3] K
Metallicity [Fe/H]-0.361 dex
Other designations
Gaia DR3 2102587087846067712, KOI-456, KIC 7269974, 2MASS J19110565+4252094[5]
Database references
SIMBADdata
KICdata

Kepler-160 is a main-sequence star approximately the width of our Galactic arm away in the constellation Lyra, first studied in detail by the Kepler Mission, a NASA-led operation tasked with discovering terrestrial planets. The star, which is very similar to the Sun in mass and radius,[4][3] has three confirmed planets and one unconfirmed planet orbiting it.

Characteristics

[edit]

The star Kepler-160 is rather old, having no detectable circumstellar disk.[6] The star's metallicity is unknown, with conflicting values of either 40% or 160% of solar metallicity reported.[7][8]

Despite having at least one potentially Earth-like planet (KOI-456.04), the Breakthrough Listen search for extraterrestrial intelligence found no potential technosignatures.[9]

Planetary system

[edit]

The two planetary candidates in the Kepler-160 system were discovered in 2010, published in early 2011[10] and confirmed in 2014.[11] The planets Kepler-160b and Kepler-160c are not in orbital resonance despite their orbital periods ratio being close to 1:3.[12]

An additional rocky transiting planet candidate KOI-456.04, located in the habitable zone, was detected in 2020,[3] and more non-transiting planets are suspected due to residuals in the solution for the transit timing variations. From what researchers can tell, KOI-456.04 looks to be less than twice the size of Earth and is apparently orbiting Kepler-160 at about the same distance from Earth to the sun (one complete orbit is 378 days). Perhaps most important, it receives about 93% as much light as Earth gets from the sun.[13] Nontransiting planet candidate Kepler-160d has a mass between about 1 and 100 Earth masses and an orbital period between about 7 and 50 d.[3]

The Kepler-160 planetary system[3]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b 0.05511+0.0019
−0.0037
4.309397+0.000013
−0.000012
0 1.715+0.061
−0.047
 R🜨
c 0.1192+0.004
−0.008
13.699429±0.000018 0 3.76+0.23
−0.09
 R🜨
d 1—100 M🜨 7—50
e (unconfirmed) 1.089+0.037
−0.073
378.417+0.028
−0.025
0 1.91+0.17
−0.14
 R🜨

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Kepler-160 is a similar to the Sun, with an effective temperature of 5471 , a radius of 1.118 solar radii, and a of 1.01 solar luminosities, located approximately 3,141 light-years away in the constellation . Discovered through NASA's mission, which operated from 2009 to 2013, the star hosts a multi-planet system that includes two confirmed transiting planets—Kepler-160 b, a with a radius of 1.72 radii and an of 4.31 days, and Kepler-160 c, a Neptune-sized world with a radius of 3.76 radii and an of 13.7 days—as well as a non-transiting , Kepler-160 d, with an estimated between 1 and 100 masses and an of approximately 30 days. The system's most notable feature is the transiting KOI-456.04 (also known as Kepler-160 e), a with a radius of 1.91 radii and an of 378.4 days, positioned in the star's where it receives about 93% of 's incident stellar flux, making it one of the most Earth-like exoplanet candidates known in terms of size, insolation, and host star similarity (as of 2025). This configuration, a validated with a false positive probability of 0.18% (corresponding to >99% confidence of being genuine), highlights Kepler-160 as a key target for studies of potentially habitable worlds around Sun-like stars.

Stellar properties

Physical parameters

Kepler-160 is a , closely resembling the Sun in its fundamental characteristics. It is located in the constellation at a distance of 3,060 ± 40 light-years (940 ± 12 pc) from , as determined from Gaia DR3 parallax measurements. The star has a radius of 1.1180.045+0.015R1.118^{+0.015}_{-0.045} \, R_\odot, an of 5,47137+115K5,471^{+115}_{-37} \, \mathrm{K}, and a of 1.01±0.05L1.01 \pm 0.05 \, L_\odot. Its mass is 0.970.06+0.05M0.97^{+0.05}_{-0.06} \, M_\odot, derived from spectral analysis and models. The surface gravity is logg=4.470.12+0.05\log g = 4.47^{+0.05}_{-0.12} (in cgs units), consistent with a main-sequence dwarf. A photometric of Kepler curves reveals a period of approximately 22 days, indicated by the dominant peak in the Lomb-Scargle . These parameters position Kepler-160 as a , with properties enabling detailed comparisons to the Sun in studies of planetary systems.

Age and activity

Kepler-160 is estimated to be older than the Sun, with spectroscopic analyses placing its age at 8.91.7+4.28.9_{-1.7}^{+4.2} billion years, indicating a mature main-sequence G-type star. Other gyrochronological and isochrone-based estimates vary, ranging from approximately 1.6 Gyr to 6.0 Gyr, reflecting uncertainties in models for solar analogs. This advanced evolutionary stage suggests the absence of a detectable circumstellar disk, as protoplanetary disks typically dissipate within a few hundred million years, consistent with the star's maturity. Measurements of Kepler-160's show discrepancies across spectroscopic surveys. Some analyses report near-solar abundances with [Fe/H] ≈ 0.14 ± 0.04 dex or 0.20 ± 0.04 dex, corresponding to roughly 140–160% of solar . In contrast, other determinations yield lower values, such as [Fe/H] ≈ -0.01 dex or even -0.36 dex, implying 40% or less solar abundance; these differences likely arise from variations in modeling and data quality in the California-Kepler Survey. Resolving these inconsistencies would refine models of the star's formation and evolution. The star exhibits low levels of chromospheric activity, typical of a mature , with no prominent flares or starspots detected in the Kepler light curves after detrending for instrumental effects. Photometric variability is dominated by low-frequency signals (periods ≳ 10 days), consistent with subdued in an aged . Lomb-Scargle analysis of the reveals a potential period of approximately 22 days, aligning with expectations for a middle-aged G dwarf similar to the Sun's 25-day equatorial . This quiescent activity profile supports long-term orbital stability for inner planets, potentially enhancing habitability prospects in the system's .

Discovery and characterization

Kepler Space Telescope observations

The , launched in 2009, conducted high-precision photometric observations of the Kepler-160 field from May 2009 to September 2013, monitoring the star's brightness to detect periodic dips indicative of planetary transits. Kepler-160, designated KOI-456 in the catalog, was first identified as hosting transiting planet candidates during the analysis of early mission data collected in quarters Q1 through Q2 (2009–2010). These initial candidates, KOI-456.01 and KOI-456.02, were announced in the first Kepler planet candidate catalog, which reported 1,235 potential transiting exoplanets based on transit searches in the pre-processed light curves. The detection relied on the transit method, where the planets pass in front of the star from the observer's perspective, causing measurable reductions in stellar flux. For Kepler-160, the light curves revealed two distinct periodic signals corresponding to the inner planets. Kepler-160 b (KOI-456.01) exhibits an orbital period of 4.309397 ± 0.000013 days, while Kepler-160 c (KOI-456.02) has an orbital period of 13.699429 ± 0.000018 days, both derived from phase-folding the Kepler long-cadence photometry and fitting transit models to the data. These periods place the planets in close orbits, with b completing a full revolution in approximately 4.3 days and c in about 13.7 days, as confirmed through statistical validation of the multi-planet system in 2014. Further analysis of Kepler data from quarters Q1–Q12 validated the candidates as bona fide planets, ruling out false positives such as through centroid offsets, secondary searches, and pixel-level contrast tests. The 2014 validation effort incorporated statistical false positive probabilities below 1% for both planets, establishing Kepler-160 b and c as the first confirmed members of the system.

Validation and follow-up studies

The initial validation of Kepler-160 b and c occurred in 2014 through statistical analysis of Kepler light curves from quarters Q1–Q12, which assessed false positive probabilities for multi-planet candidates and confirmed the planets to better than 99% confidence using light curve modeling and multiplicity statistics. In 2020, Heller et al. reanalyzed the archival Kepler data using the transit least-squares on pre-processed from Data Release 25, identifying and validating a new transiting candidate, KOI-456.04, based on three observed transits with consistent depths and timings. The validation employed the package to compute a false positive probability of 1.81 × 10⁻³ for the three-planet scenario and model-shift tests to rule out instrumental artifacts, achieving approximately 85% reliability for the candidate. Follow-up methods included reprocessing of archival Kepler photometry with detrending via biweight filters and fitting to refine transit parameters, alongside N-body simulations to investigate transit timing variations (TTVs). TTV analysis revealed substantial variations in Kepler-160 c's timings, with amplitudes of about 20 minutes and periods around 879 days, attributed to gravitational perturbations from a non-transiting companion rather than the validated transiting planets. These studies refined key transit parameters for the transiting bodies, including depths averaging 271 ppm for KOI-456.04 with individual measurements of 207 ± 54 ppm, 237 ± 46 ppm, and 370 ± 41 ppm, and updated durations and error bars drawn from the Kepler Object of Interest table in Data Release 25. The results integrated prior Kepler observations into a comprehensive system model, confirming the architecture without requiring new telescopic data.

Planetary system

Inner transiting planets

The inner transiting planets of the Kepler-160 system, Kepler-160 b and Kepler-160 c, were identified through photometric observations by the and validated using transit light curve analysis. These planets orbit close to their Sun-like host star, receiving high levels of stellar insolation that influences their thermal properties. Kepler-160 b is a compact super-Earth-sized world, while Kepler-160 c is a larger body consistent with a composition. Kepler-160 b has a radius of 1.7150.047+0.0611.715^{+0.061}_{-0.047} radii and orbits at a semi-major axis of 0.055110.0037+0.00190.05511^{+0.0019}_{-0.0037} AU, corresponding to an of approximately 4.3 days. Its equilibrium temperature, calculated assuming zero and efficient heat redistribution, is about 1134 K, rendering it a hot Venus-like with intense surface conditions. Due to the absence of reported signals in follow-up observations, the mass of Kepler-160 b remains unconstrained, with upper limits likely below 10 masses. Kepler-160 c is significantly larger, with a radius of 3.760.09+0.233.76^{+0.23}_{-0.09} radii and a semi-major axis of 0.11920.008+0.0040.1192^{+0.004}_{-0.008} AU, yielding an orbital period of roughly 13.7 days. This places it in a potential category, possibly featuring a hydrogen-helium envelope over a rocky core. Its equilibrium temperature is approximately 771 K, still elevated but cooler than that of planet b. Similar to b, no radial velocity detections have constrained the mass of c, implying upper limits below 10 Earth masses. The orbital period ratio between Kepler-160 c and b is close to 3:1 (approximately 3.18), suggesting potential for mean-motion resonance, but detailed transit timing variation (TTV) analysis reveals no significant evidence of resonant interactions or TTV signals attributable to mutual gravitational perturbations between the two planets. Instead, observed TTVs for c are primarily linked to an inner non-transiting companion.
PlanetRadius (R⊕)Semi-major Axis (AU)Equilibrium Temperature (K)Mass Upper Limit (M⊕)
Kepler-160 b1.7150.047+0.0611.715^{+0.061}_{-0.047}0.055110.0037+0.00190.05511^{+0.0019}_{-0.0037}~1134<10
Kepler-160 c3.760.09+0.233.76^{+0.23}_{-0.09}0.11920.008+0.0040.1192^{+0.004}_{-0.008}~771<10

Habitable zone candidate

The super-Earth candidate KOI-456.04, proposed as Kepler-160 e, is a transiting planet with a radius of 1.910.14+0.17R1.91^{+0.17}_{-0.14} R_\oplus, making it slightly larger than Earth but within the size range for potentially rocky worlds. This candidate orbits its host star at a semi-major axis of 1.0890.073+0.0371.089^{+0.037}_{-0.073} AU, comparable to Earth's distance from the Sun, with an orbital period of 378.4170.025+0.028378.417^{+0.028}_{-0.025} days. KOI-456.04 receives an insolation flux of 0.930.12+0.180.93^{+0.18}_{-0.12} times that incident on , positioning it firmly within the optimistic of Kepler-160, where conditions could allow for liquid under certain atmospheric assumptions. This flux level suggests equilibrium temperatures around 245 , potentially supporting temperate surface conditions if the planet maintains an Earth-like and . The candidate was identified and validated in 2020 through advanced reprocessing of Kepler light curves using the , combined with transit injection tests to confirm the signal's authenticity and rule out instrumental artifacts. These methods, including detrending with a Tukey’s biweight filter and fitting, yielded a multiple event statistic of 10.7 and a low false positive probability of 1.81×1031.81 \times 10^{-3}, indicating high reliability as a genuine planetary signal rather than a false positive.

Non-transiting companions

In the Kepler-160 system, evidence for non-transiting companions arises primarily from transit timing variations (TTVs) observed in the transiting planet Kepler-160 c, which has an of approximately 13.7 days. These TTVs, with an of about 20 minutes and a periodicity of roughly 879 days, indicate gravitational perturbations from an unseen body, as deviations from a strictly linear cannot be explained by stellar activity or instrumental effects alone. The candidate non-transiting planet, designated Kepler-160 d, was inferred through dynamical modeling involving N-body simulations and (MCMC) fitting to the TTV signal of Kepler-160 c. This approach assumes low mutual inclinations between the planets and explores orbital configurations near mean-motion resonances, such as 5:2 or 7:2 with Kepler-160 c, to match the observed timing deviations. The resulting model attributes the perturbations solely to a single companion, with no compelling evidence for additional perturbers in the current dataset. Kepler-160 d is estimated to have a mass between 1 and 100 Earth masses (M⊕) and an orbital period ranging from approximately 4 to 38 days, placing it in the planetary regime rather than a stellar or brown dwarf companion. These parameters vary broadly depending on the assumed resonance and orbital setup, as the lack of direct radial velocity or transit observations limits precision; for instance, shorter periods near 7 days yield higher masses, while longer periods up to 50 days allow lower masses. The inferred location of Kepler-160 d is interior to Kepler-160 c, likely between the inner transiting Kepler-160 b (period ~4.3 days) and c, which could influence the overall system dynamics by introducing resonant interactions that enhance long-term stability. N-body simulations demonstrate that such configurations remain stable over at least 1 million years, avoiding close encounters or ejections, though broader parameter explorations reveal possibilities for multiple low-mass bodies contributing to the TTV signal if future observations refine the data. Additional monitoring is required to narrow these uncertainties and confirm the companion's existence.

Scientific significance

Habitability prospects

The (HZ) around Kepler-160, a G2V star with luminosity approximately 1.1 times that of the Sun, is defined by conservative boundaries that account for the potential for liquid water on a rocky 's surface under Earth-like atmospheric conditions. The conservative inner boundary is set by the runaway limit, where feedback leads to rapid atmospheric loss, while the outer boundary is determined by the maximum CO₂ , beyond which CO₂ condenses out and cooling occurs. Optimistic boundaries extend these limits inward to the moist threshold and outward to conditions resembling early Mars or , allowing for a broader range of potential scenarios. The candidate KOI-456.04 receives an incident stellar flux of 0.93 ± 0.15 times that of (F⊕), placing it firmly within both conservative and optimistic HZ boundaries for this star. KOI-456.04, with a radius of 1.91 ± 0.16 ⊕, is consistent with a rocky composition if it retains less than 0.75% of its mass in a hydrogen-helium , making it a viable candidate for . An Earth-like could raise its from approximately 245 K to around +5 °C, supporting liquid surface water under suitable atmospheric pressures. Its orbital period of 378 days precludes significant , avoiding extreme temperature contrasts that could hinder global . This system bears a close resemblance to the Earth-Sun pair, with KOI-456.04 orbiting at a separation scaled similarly to 1 and receiving comparable insolation from a Sun-like host. The star's estimated age of about 8.9 Gyr indicates long-term stability, with low activity levels (possible rotation period ~22 days) that minimize disruptive flares and support prolonged conditions favorable for . In contrast, the inner transiting planets Kepler-160 b and c receive fluxes far exceeding Earth's, rendering them uninhabitable due to extreme heat. Despite these prospects, challenges persist, including (UV) flux from the G2V host comparable to the Sun's, which could erode atmospheres over billions of years without sufficient magnetic . Additionally, the planet's potential for retention is uncertain, as gradual hydrodynamic escape during the star's main-sequence might have depleted volatiles, though the system's maturity suggests any remaining could have persisted long enough for biological processes.

Searches for extraterrestrial signals

The Sun-like nature of Kepler-160 and the presence of the planet candidate KOI-456.04 have motivated searches for technosignatures from this system, as it represents one of the closest analogs to the Sun-Earth pair among known exoplanets. In June 2020, the Breakthrough Listen project performed dedicated radio observations of Kepler-160 using the 100-m to seek artificial emissions, totaling approximately 80 minutes on June 14. The observations targeted potential signals from the star or its planets, including KOI-456.04, but detected none. The search spanned 1.1–1.9 GHz (L-band), 1.8–2.8 GHz (S-band), and 3.95–8.0 GHz (C-band), employing the turboSETI pipeline for analysis. It was sensitive to technosignatures (3 Hz resolution, drift rates ±4 Hz s⁻¹) and pulsed signals (5 ms duration), with no candidates identified after vetting for radio frequency interference. At the system's distance of 3,141 light-years, the observations set upper limits on transmitter equivalent isotropically radiated power (EIRP) of 5.9 × 10^{14} W for signals and 7.3 × 10^{12} W for signals—levels comparable to Earth's most powerful radars if originating from a technological civilization. Future efforts could include confirming KOI-456.04's planetary nature with the space telescope and extending similar radio surveys to other candidates from TESS and missions. Atmospheric transmission spectroscopy with the offers prospects for detecting potential biosignatures, such as or oxygen, in systems like Kepler-160 featuring Sun-like hosts and worlds.
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