astronomy

Kepler-1708b

Kepler-1708b is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kepler-1708b rather than just read about it. In short: Kepler-1708b (previously known as KIC 7906827.01) is a Jupiter-sized exoplanet orbiting the Sun-like star Kepler-1708, located in the constellation of Cygnus approximately 5,600 light years away from Earth. It was first detected in 2011 by NASA's Kepler mission using the transit method, but was not identified as a candidate planet until 2019.

Key takeaways

Kepler-1708b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kepler-1708b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-1708b from memory before moving on to harder problems.

Reference excerpt

Kepler-1708b (previously known as KIC 7906827.01) is a Jupiter-sized exoplanet orbiting the Sun-like star Kepler-1708, located in the constellation of Cygnus approximately 5,600 light years away from Earth. It was first detected in 2011 by NASA's Kepler mission using the transit method, but was not identified as a candidate planet until 2019. In 2021, a candidate Neptune-sized exomoon in orbit around Kepler-1708b was found by astronomer David Kipping and colleagues in an analysis using Kepler transit data. Some subsequent research has raised discrepancies about the possible existence of an exomoon, similar to that of Kepler-1625b but even more recent research still finds the existence of an exomoon likely.

Characteristics

Mass and radius Kepler-1708b is a gas giant planet slightly smaller than Jupiter in size, with a radius of 0.89 Jupiter radii. The mass of the planet remains yet to be measured; precise analysis of its transit timings place a 2-sigma upper limit of <4.6 Jupiter masses. This mass upper limit predicts a maximum radial velocity amplitude of <98 m/s—although within reach of the most precise spectrographs available, the faintness of Kepler-1708b's host star would make observations difficult.

Orbit and temperature Kepler-1708b orbits about 1.64 astronomical units from its host star and completes one revolution every 737.11 days or 2.02 years, comparable to the orbit of Mars in the Solar System. At this distance, Kepler-1708b lies within the habitable zone of its host star, where it receives an insolation flux 0.561+0.074−0.068 times that of Earth at a relatively cool equilibrium temperature of 200–300 kelvins (−73–27 °C; −100–80 °F). The eccentricity of its orbit is unmeasured and is given a 2-sigma upper limit of <0.40.

Host star Kepler-1708b orbits around the Sun-like star Kepler-1708, located in the constellation of Cygnus 5,580 ± 240 ly (1,712 ± 75 pc) light years away from Earth. At an apparent magnitude of 16, this star is too faint to be seen by the naked eye. The star's celestial coordinates based on the J2000 epoch are: RA 19h 47m 17.79s, Dec 43° 37′ 29.4″. The European Space Agency's Gaia satellite has measured a stellar parallax of 0.5730±0.0340 milliarcseconds (mas) and directional proper motion components of RA −0.770±0.057 mas/yr, Dec −5.005±0.059 mas/yr. Kepler-1708 is known by other designations from various star catalogues including: UCAC4 669-077544, KIC 7906827, TIC 272716898, 2MASS J19471778+4337295, WISE J194717.78+433729.2, and Gaia DR2 2078801971283008128. Kepler-1708 is slightly larger and more massive than the Sun, with a mass of 1.088±0.072 M☉ and radius of 1.117±0.064 R☉. It is also hotter and more luminous than the Sun, with an effective temperature of 6,157+231−202 K and a bolometric luminosity of 1.521 L☉. Based on these properties, Kepler-1708 is likely an F-type main sequence star with a Sun-like metallicity of [Fe/H] = 0.0±0.2 dex and an age of 3.16±2.26 billion years.

Potential exomoon

In 2021, David Kipping and colleagues performed a search for exomoons around cool, long-period gas giant exoplanets using Kepler photometric data. Out of a sample of 70 exoplanets analyzed, only Kepler-1708b exhibited signs of an orbiting exomoon manifesting as faint, secondary transits accompanying the planet's transits. This possible exomoon, designated Kepler-1708b I, appears to measure below the size of Neptune at 2.6 times Earth's radius. It likely orbits coplanar to its host planet from a distance up to 12 planetary radii—comparable to the distance between Jupiter and its moon Europa, or twice the Earth–Moon distance. The extraordinarily large size of Kepler-1708b I is reminiscent of Kepler-1625b I, another Neptune-sized exomoon candidate previously reported by Kipping et al. in 2017. Additional observations are necessary to confirm or refute the exomoon's existence—only two transits by Kepler-1708b and its possible exomoon have been observed, and no transit timing variations can be determined as of yet. Kipping et al. determine that the probability of detecting one false positive exomoon in the studied sample of 70 exoplanets was <50%. A follow-up study suggested Kepler-1708b I is likely undetectable with the Hubble Space Telescope, but the James Webb Space Telescope should be able to confirm or refute its existence. In 2024, a paper was published disputing both 1625b I and 1708b I’s existences, but a reply to this paper refute most claims given, and conclude that the existence of an exomoon is likely but need additional observations.

See also Kepler-1625b 2MASS J11193254–1137466 AB PDS 70 V1400 Centauri

Notes

References

External links Astronomers Find Evidence for a Second Supermoon Beyond Our Solar System, Kim Martineau, Columbia News, Columbia University, 13 January 2022 KIC 7906827 – Kepler Time Series Visualizer NASA Exoplanet Archive, Infrared Processing and Analysis Center Planet Kepler-1708 b, The Extrasolar Planets Encyclopaedia, last updated 14 January 2022

Worked examples

Example 1 — a first encounter with Kepler-1708b

Start with the simplest possible case. Write down what Kepler-1708b claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kepler-1708b before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kepler-1708b ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kepler-1708b

In research: Kepler-1708b appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kepler-1708b in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kepler-1708b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), Exoplanets discovered by the Kepler space telescope, Exoplanets discovered in 2022, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-1708b outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Kepler-1708b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-1708b means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kepler-1708b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-1708b in simple terms?

Why does Kepler-1708b matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kepler-1708b?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kepler-1708b.