astronomy

HD 140913

HD 140913 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 140913 rather than just read about it. In short: HD 140913 is a Sun-like star located in the northern constellation of Corona Borealis (The Northern Crown). It is too faint to be visible to the naked eye with an apparent visual magnitude of 8.07.

Key takeaways

HD 140913 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 140913 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 140913 from memory before moving on to harder problems.

Reference excerpt

HD 140913 is a Sun-like star located in the northern constellation of Corona Borealis (The Northern Crown). It is too faint to be visible to the naked eye with an apparent visual magnitude of 8.07. The star is located at a distance of 159 light-years from the Sun based on parallax. Prior to the discovery of a companion, this served as an IAU radial velocity standard, and it is receding from the Sun at a rate of +37 km/s. The space velocity components of this star are (U, V, W) = (-21.77, -14.42, 1.67).

Physical characteristics HD 140913 is a solar-type star with a spectral type of G0V. It is estimated to be seven billion years old and is spinning with a projected rotational velocity of 9.7 km/s. The star is about the same size as the Sun and 92% of its mass. It is radiating 1.3 times the Sun's luminosity from its photosphere at an effective temperature of 6,090 K.

Companion The detection of an orbiting companion, designated HD 140913 B, was announced in 1994. The minimum mass of this object is 43.2 times the mass of Jupiter, making it a brown dwarf candidate. Alternatively, it may be an under-mass helium white dwarf that has lost its envelope during a mass transfer. It orbits the host star about every 148 days with an eccentricity (ovalness) of ~0.57 and a semimajor axis of at least 0.55 AU. In 2023, the true mass of this companion was determined using Gaia astrometry. Two different studies find masses ranging from about 75 to about 93 Jupiter masses, placing this object near the boundary between brown dwarfs and low-mass stars.

References

Worked examples

Example 1 — a first encounter with HD 140913

Start with the simplest possible case. Write down what HD 140913 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 140913 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 140913 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 140913

In research: HD 140913 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 140913 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 140913 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Binary stars, Brown dwarfs, Corona Borealis, so understanding it makes those chapters shorter.
In everyday life: Look for HD 140913 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 140913 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 140913 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 140913 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 140913 in simple terms?

HD 140913 is a Sun-like star located in the northern constellation of Corona Borealis (The Northern Crown). It is too faint to be visible to the naked eye with an apparent visual magnitude of 8.07.

Why does HD 140913 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 140913?

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 140913.