astronomy

TrES-2A

TrES-2A 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 TrES-2A rather than just read about it. In short: GSC 03549-02811 (sometimes referred to as Kepler-1, or either TrES-2A or TrES-2 parent star in reference to its exoplanet TrES-2b) is a binary star system containing a G-type main-sequence star similar to the Sun. This star is located approximately 704 light-years away in the constellation of Draco.

Key takeaways

TrES-2A belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect TrES-2A to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TrES-2A from memory before moving on to harder problems.

Reference excerpt

GSC 03549-02811 (sometimes referred to as Kepler-1, or either TrES-2A or TrES-2 parent star in reference to its exoplanet TrES-2b) is a binary star system containing a G-type main-sequence star similar to the Sun. This star is located approximately 704 light-years away in the constellation of Draco. The apparent magnitude of this star is 11.41, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night. The age of this star is about 5 billion years.

Nomenclature The designation GSC 03549-02811 comes from the Guide Star Catalog. The star is often called TrES-2, in reference to its planet discovered by the Trans-Atlantic Exoplanet Survey (TrES). The discovery paper and the SIMBAD database use this designation for the planet itself, but other sources call the star TrES-2 (or TrES-2A) and the planet TrES-2b, following the standard exoplanet naming convention. In keeping with the planet being component b, the companion star is designated TrES-2C, although it is also designated Kepler-1B. The planet was also observed by the Kepler space telescope, and so the star is also known as Kepler-1. Since the planet transits the star, the star is classified as a planetary transit variable and has received the variable star designation V581 Draconis.

Binary star In 2008 a study was undertaken of fourteen stars with exoplanets that were originally discovered using the transit method through relatively small telescopes. These systems were re-examined with the 2.2M reflector telescope at the Calar Alto Observatory in Spain. This star system, along with two others, was determined to be a previously unknown binary star system. The previously unknown secondary star is a dim magnitude 15 K-type star separated by about 232 AU from the primary, appearing offset from the primary by about one arc second in the images. This discovery resulted in a significant recalculation of parameters for both the planet and the primary star.

Planetary system

In 2006, the exoplanet TrES-2b was discovered by the Trans-Atlantic Exoplanet Survey using the transit method. It was also within the field of view of the Kepler Mission planet-hunter spacecraft. This system continues to be studied by other projects and the parameters are continuously improved. The planet orbits the primary star. TrES-2b is a hot Jupiter, with a mass and size similar to those of Jupiter but an orbital period of only two days. Its orbit is prograde relative to its star's rotation. In 2011, TrES-2b was found to have a very low albedo, reflecting less than 1 percent of the light from its star, making it the darkest known exoplanet at the time. However, it also emits a significant amount of light because its surface temperature is so hot that it glows red. Due to its close orbit, it is assumed to be tidally locked to its parent star.

The Kepler mission

In March 2009, NASA launched the Kepler spacecraft. This spacecraft was a dedicated mission to discover extrasolar planets by the transit method from solar orbit. In April 2009 the project released the first light images from the spacecraft, and TrES-2b was one of two objects highlighted in these images. Although TrES-2b was not the only known exoplanet in the field of view of this spacecraft, it was the only one identified in the first-light images. This object was important for calibration and check-out.

Illustrations

Worked examples

Example 1 — a first encounter with TrES-2A

Start with the simplest possible case. Write down what TrES-2A 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 TrES-2A 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 TrES-2A 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 TrES-2A

In research: TrES-2A 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 TrES-2A 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: TrES-2A is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Draco (constellation), G-type main-sequence stars, so understanding it makes those chapters shorter.
In everyday life: Look for TrES-2A 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 TrES-2A in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TrES-2A 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 TrES-2A out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TrES-2A in simple terms?

Why does TrES-2A 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 TrES-2A?

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 TrES-2A.