astronomy

NN Serpentis

NN Serpentis 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 NN Serpentis rather than just read about it. In short: NN Serpentis (abbreviated NN Ser) is an eclipsing post-common envelope binary system approximately 1670 light-years away. The system comprises an eclipsing white dwarf and red dwarf.

Key takeaways

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

Reference excerpt

NN Serpentis (abbreviated NN Ser) is an eclipsing post-common envelope binary system approximately 1670 light-years away. The system comprises an eclipsing white dwarf and red dwarf. The two stars orbit each other every 0.13 days. In 1982, Richard F. Green et al. found the star in the Palomar Green Survey, and determined it to be a possible cataclysmic variable star. They gave it the name PG 1550+131. Photometric observations by John W. Wilson et al. in 1983 showed that PG 1550+131 was indeed a variable star. Reinhold Haefner discovered that the star is an eclipsing binary, in 1988. It was given its variable star designation, NN Serpentis, in 1989.

Planetary system A planetary system has been inferred to exist around NN Ser by several teams. All of these teams rely on the fact that Earth sits in the same plane as the NN Serpentis binary star system, so humans can see the larger red dwarf eclipse the white dwarf every 0.13 days. Astronomers are then able to use these frequent eclipses to spot a pattern of small but significant irregularities in the orbit of stars, which could be attributed to the presence and gravitational influence of circumbinary planets.

Chen (2009) used these "eclipse timing variations" to suggesting a putative orbital period spanning between 30 and 285 years and a minimum mass between 0.0043 and 0.18 Solar masses. In late 2009, Qian estimated a minimum mass of 10.7 Jupiter masses and orbital period of 7.56 years for this planet, probably located at 3.29 Astronomical Units. This has since been disproven by further measurements of the eclipse times of the binary stars. In late 2009 and 2010, researchers from the UK (University of Warwick and the University of Sheffield), Germany (Georg-August-Universitat in Göttingen, Eberhard-Karls-Universitat in Tübingen), Chile (Universidad de Valparaíso), and the United States (University of Texas at Austin) suggested that the eclipse timing variations are caused by two gas giant planets. The more massive gas giant is about 6 times the mass of Jupiter and orbits the binary star every 15.5 years, the other orbits every 7.75 years and is about 1.6 times the mass of Jupiter. All published planetary models have failed to predict changes in eclipse timing since 2018, suggesting that a different explanation for the eclipse timing variations may be needed.

See also Algol HW Virginis CM Draconis Kepler-16 Kepler-47, another binary system with 3 planets

References

External links The Extrasolar Planet Encyclopaedia — Catalog Listing UK Astronomers Help Find Snooker Star System

Illustrations

Worked examples

Example 1 — a first encounter with NN Serpentis

Start with the simplest possible case. Write down what NN Serpentis 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 NN Serpentis 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 NN Serpentis 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 NN Serpentis

In research: NN Serpentis 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 NN Serpentis 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: NN Serpentis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Eclipsing binaries, Hypothetical planetary systems, M-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for NN Serpentis 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 NN Serpentis in 20 minutes

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

Frequently asked questions

What is NN Serpentis in simple terms?

NN Serpentis (abbreviated NN Ser) is an eclipsing post-common envelope binary system approximately 1670 light-years away. The system comprises an eclipsing white dwarf and red dwarf.

Why does NN Serpentis 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 NN Serpentis?

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 NN Serpentis.