astronomy

PH1b

PH1b 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 PH1b rather than just read about it. In short: PH1b (standing for "Planet Hunters 1"), or by its NASA designation Kepler-64b, is an extrasolar planet found in a circumbinary orbit in the quadruple star system Kepler-64. The planet was discovered by two amateur astronomers from the Planet Hunters project of amateur astronomers using data from the Kepler space telescope with assistance of a Yale University team of international astronomers.

Key takeaways

PH1b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PH1b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PH1b from memory before moving on to harder problems.

Reference excerpt

PH1b (standing for "Planet Hunters 1"), or by its NASA designation Kepler-64b, is an extrasolar planet found in a circumbinary orbit in the quadruple star system Kepler-64. The planet was discovered by two amateur astronomers from the Planet Hunters project of amateur astronomers using data from the Kepler space telescope with assistance of a Yale University team of international astronomers. The discovery was announced on 15 October 2012. It is the first known transiting planet in a quadruple star system, first known circumbinary planet in a quadruple star system, and the first planet in a quadruple star system found. It was the first confirmed planet discovered by PlanetHunters.org. An independent and nearly simultaneous detection was also reported from a revision of Kepler space telescope data using a transit detection algorithm.

Star system The giant planet is Neptune-sized, about 20-55 Earth-masses (M🜨). It has a radius 6.2 times that of Earth. The star system is 7200 light years from Earth. The planet orbits a close binary, with a more distant binary orbiting at a distance, forming the quadruple star system. The star system has the Kepler Input Catalogue name KIC 4862625 as well as the designation Kepler-64. The close binary (Aa+Ab) that the planet circles has an orbital period of 20 days. They form an eclipsing binary pair. The two stars are (Aa) 1.384 solar mass (M☉) F-type main-sequence star and (Ab) 0.336 M☉ red dwarf. The planet orbits this binary pair in a 138.3-day orbit. The binary pairs have a separation of 1000 AU. A photometric-dynamical model was used to model the planetary system of the close binary pair. The distant binary (Ba+Bb) have a pair separation of 60 AU. The two stars are (Ba) 0.99 M☉ G-type main-sequence star and (Bb) 0.51 M☉ red dwarf. The quadruple star system has an estimated age of two billion years (2 gigayears). The system is located at right ascension 19h 52m 51.624s declination +39° 57′ 18.36″, so also has a 2MASS catalogue entry of 2MASS 19525162+3957183

Discovery

Kian Jin Jek (Chinese: 易建仁, son of Jek Yeun Thong), from San Francisco, and Robert Gagliano, from Cottonwood, Arizona, spotted the signature of the planet in the Kepler data, and it was reported through the PlanetHunters.org program run by Dr. Chris Lintott, from Oxford University. Kian Jek first spotted a light dip indicative of a transit in May 2011. JKD reported a second. Robert Gagliano performed a systematic search, and confirmed the second dip, and found a third, in February 2012. Using this, Kian predicted another transit, and found it. The planet was subsequently detected by eclipsing binary timing variation method. At the time of discovery, it was the sixth known circumbinary planet.

Role as a benchmark system The planet PH1b and Kepler-35b were used as a benchmark system for automated detection algorithms. As a benchmark system PH1 is used to improve the algorithm and to demonstrate improvement in the detection of circumbinary planets.

See also List of extrasolar planet firsts PH2 b

References

Further reading Discovery Announcement: PlanetHunters.org, "PH1 : A planet in a four-star system", 15 October 2012 (accessed 20 October 2012) Discovery Paper: arXiv. "Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star System", Megan E. Schwamb, Jerome A. Orosz, Joshua A. Carter, William F. Welsh, Debra A. Fischer, Guillermo Torres, Andrew W. Howard, Justin R. Crepp, William C. Keel, Chris J. Lintott, Nathan A. Kaib, Dirk Terrell, Robert Gagliano, Kian J. Jek, Michael Parrish, Arfon M. Smith, Stuart Lynn, Robert J. Simpson, Matthew J. Giguere, Kevin Schawinski, 2012 October, arXiv:1210.3612 ; Bibcode:2012arXiv1210.3612S ;

Worked examples

Example 1 — a first encounter with PH1b

Start with the simplest possible case. Write down what PH1b 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 PH1b 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 PH1b 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 PH1b

In research: PH1b 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 PH1b 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: PH1b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Circumbinary planets, Cygnus (constellation), Discoveries by amateur astronomers, so understanding it makes those chapters shorter.
In everyday life: Look for PH1b 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 PH1b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PH1b 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 PH1b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PH1b in simple terms?

Why does PH1b 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 PH1b?

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 PH1b.