astronomy

HD 142

HD 142 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 HD 142 rather than just read about it. In short: HD 142 is a wide binary star system in the southern constellation of Phoenix. The main component has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.7.

Key takeaways

HD 142 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HD 142 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 142 from memory before moving on to harder problems.

Reference excerpt

HD 142 is a wide binary star system in the southern constellation of Phoenix. The main component has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.7. The system is located at a distance of 85.5 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of +6 km/s. The primary component is an F-type main-sequence star with a stellar classification of F7V, which indicates it is undergoing core hydrogen fusion. It is an estimated 2.5 billion years old and is spinning with a projected rotational velocity of 10 km/s. The star has 1.25 times the mass of the Sun and 1.4 times the Sun's radius. It is radiating 2.9 times the luminosity of the Sun from its photosphere at an effective temperature of 6,349 K. A magnitude 11.5 companion star was detected in 1894 making this a binary star system. The binary companion was confirmed to be gravitationally bound in 2007 and determined to be a red dwarf of spectral type K8.5-M1.5 with 54% of the Sun's mass. The pair have a projected separation of 120.6 AU.

Planetary system In 2001, the Anglo-Australian Planet Search team led by Chris Tinney announced the discovery of an extrasolar planet orbiting the primary star. An additional linear trend in the radial velocity data was noticed in 2006 that could have been due to another planet or to the stellar companion. In 2012, additional measurements allowed the detection of a second planet. A third possible planet with a period of 108 days was seen in the data, but with a false alarm probability of five percent. Another paper by the same team updated the parameters for b and c but did not mention the possible planet d. An astrometric measurement of HD 142 b's inclination and true mass was published in 2022 as part of Gaia DR3. Another 2022 study determined the inclination and true mass of planet c, and confirmed the existence of planet d.

Illustrations

Worked examples

Example 1 — a first encounter with HD 142

Start with the simplest possible case. Write down what HD 142 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 HD 142 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 HD 142 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 HD 142

In research: HD 142 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 HD 142 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: HD 142 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Bright Star Catalogue objects, Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 142 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 HD 142 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 142 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 HD 142 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 142 in simple terms?

HD 142 is a wide binary star system in the southern constellation of Phoenix. The main component has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.7.

Why does HD 142 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 HD 142?

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 HD 142.