astronomy

HAT-P-1b

HAT-P-1b 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 HAT-P-1b rather than just read about it. In short: HAT-P-1b is an extrasolar planet orbiting the Sun-like star HAT-P-1, also known as ADS 16402 B. HAT-P-1 is the dimmer component of the ADS 16402 binary star system.

Key takeaways

HAT-P-1b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HAT-P-1b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HAT-P-1b from memory before moving on to harder problems.

Reference excerpt

HAT-P-1b is an extrasolar planet orbiting the Sun-like star HAT-P-1, also known as ADS 16402 B. HAT-P-1 is the dimmer component of the ADS 16402 binary star system. It is located roughly 521 light-years away from Earth in the constellation Lacerta. HAT-P-1b is among the least dense of any of the known extrasolar planets.

Discovery HAT-P-1b was detected by searching for astronomical transits of the parent star by orbiting planets. As the planet passes in front of its parent star (as seen from Earth), it blocks a small amount of the light reaching us from the star. HAT-P-1b was first detected by a dip of 0.6% in the light from the star. This enabled determination of the planet's radius and orbital period. The discovery was made by the HATNet Project (Hungarian Automated Telescope Network) using telescopes at the Fred Lawrence Whipple Observatory on Mount Hopkins in Arizona and at the Submillimeter Array facility in Hawaii. It was confirmed and the orbital parameters determined by radial velocity measurements made at the 8.2 m Subaru and 10 m Keck telescopes, the discovery announcement being made on September 14, 2006.

Orbit and mass HAT-P-1b is located in a very close orbit to its star, taking only 4.47 days to complete. It therefore falls into the category of hot Jupiters. At only 8.27 million kilometers from the star, tidal forces would circularise the orbit unless another perturbing body exists in the system. At the present time, the existing measurements are not sufficient to determine the orbital eccentricity, so a perfectly circular orbit has been assumed by the discoverers. However, the eccentricity of the planet was calculated to be no greater than 0.067. In order to determine the mass of the planet, measurements of the star's radial velocity variations were made by the N2K Consortium. This was done by observing the Doppler shift in the star's spectrum. Combined with the known inclination of the orbit as determined by the transit observations, this revealed the mass of the planet to be 0.53 ± 0.04 times that of Jupiter.

Rotation As of August 2008, the most recent calculation of HAT-P-1b's Rossiter–McLaughlin effect and so spin-orbit angle was 3.7±2.1°.

Characteristics As evidenced by its high mass and planetary radius, HAT-P-1b is a gas giant, most likely composed primarily of hydrogen and helium. The emission from C2, CN and CH radicals in planetary atmosphere was detected in 2022. The planetary atmosphere is hazy rather than cloudy, with observed clouds area fraction 22+5−3 percent. Current theories predict that such planets formed in the outer regions of their solar systems and migrated inwards to their present orbits. HAT-P-1b is significantly larger than predicted by theoretical models. This may indicate the presence of an additional source of heat within the planet. One possible candidate is tidal heating from an eccentric orbit, a possibility which has not been ruled out from the available measurements. However, another planet with a significantly inflated radius, HD 209458 b, is in a circular orbit. An alternative possibility is that the planet has a high axial tilt, like Uranus in the Solar System. The problem with this explanation is that it is thought to be quite difficult to get a planet into this configuration, so having two such planets among the set of known transiting planets is problematic.

References

External links Media related to HAT-P-1b at Wikimedia Commons

BBC News HATnet official homepage NY Times

Illustrations

Worked examples

Example 1 — a first encounter with HAT-P-1b

Start with the simplest possible case. Write down what HAT-P-1b 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 HAT-P-1b 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 HAT-P-1b 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 HAT-P-1b

In research: HAT-P-1b 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 HAT-P-1b 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: HAT-P-1b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by HATNet, Exoplanets discovered in 2006, Giant planets, so understanding it makes those chapters shorter.
In everyday life: Look for HAT-P-1b 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “HAT-P-1b” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study HAT-P-1b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HAT-P-1b 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 HAT-P-1b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HAT-P-1b in simple terms?

HAT-P-1b is an extrasolar planet orbiting the Sun-like star HAT-P-1, also known as ADS 16402 B. HAT-P-1 is the dimmer component of the ADS 16402 binary star system.

Why does HAT-P-1b 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 HAT-P-1b?

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 HAT-P-1b.