astronomy

HD 101930

HD 101930 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 101930 rather than just read about it. In short: HD 101930, also known as GJ 3683, is an orange hued star with an orbiting exoplanet located in the southern constellation Centaurus. It has an apparent magnitude of 8.21, making it faintly visible in binoculars but not to the naked eye.

Key takeaways

HD 101930 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 101930 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 101930 from memory before moving on to harder problems.

Reference excerpt

HD 101930, also known as GJ 3683, is an orange hued star with an orbiting exoplanet located in the southern constellation Centaurus. It has an apparent magnitude of 8.21, making it faintly visible in binoculars but not to the naked eye. The system is located relatively close at a distance of 98 light years but is receding with a heliocentric radial velocity of 18.4 km/s. It has a relatively large proper motion, traversing the celestial sphere with an angular velocity of 0.320″·yr−1.

Description HD 101930 has a stellar classification of K2 V+, indicating that it is an ordinary K-type main-sequence star. It has an estimated age of 5.4 billion years, which is slightly older than the Sun. The object has 87% the radius of the Sun and an effective temperature of 5,079 K. When combined, these parameters yield a luminosity 43% that of the Sun from its photosphere. As expected with planetary hosts, HD 101930 is metal enriched, having a metallicity 26% above solar levels. The star's projected rotational velocity is similar to the Sun's, having a value of 2 km/s. A 2007 multicity survey found a co-moving companion located 73″ away, making it a binary star. It has a class of M0-1 and a mass of 0.7 M☉.

Planetary system In 2005, the discovery of an exoplanet orbiting the star was announced. This is another discovery using the radial velocity method with the HARPS spectrograph. As the inclination of the orbital plane is unknown, only a lower bound on the mass can be determined. It has at least 30% of the mass of Jupiter.

See also HD 93083 HD 102117 List of extrasolar planets HARPS spectrograph

References

External links "HD 101930". Exoplanets. Archived from the original on 2016-03-03. Retrieved 2009-05-22.

Worked examples

Example 1 — a first encounter with HD 101930

Start with the simplest possible case. Write down what HD 101930 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 101930 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 101930 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 101930

In research: HD 101930 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 101930 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 101930 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Centaurus, Durchmusterung objects, Gliese and GJ objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 101930 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 101930 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 101930 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 101930 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 101930 in simple terms?

Why does HD 101930 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 101930?

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 101930.