astronomy

HIP 5158

HIP 5158 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 HIP 5158 rather than just read about it. In short: HIP 5158 is a star with a pair of orbiting substellar companions, located in the equatorial constellation of Cetus, the whale. It has the older designation CD-23 395, which is derived from the Cordoba Durchmusterung catalogue of southern stars.

Key takeaways

HIP 5158 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HIP 5158 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HIP 5158 from memory before moving on to harder problems.

Reference excerpt

HIP 5158 is a star with a pair of orbiting substellar companions, located in the equatorial constellation of Cetus, the whale. It has the older designation CD-23 395, which is derived from the Cordoba Durchmusterung catalogue of southern stars. Based on parallax measurements, it is located 169 light years from the Sun. It has an absolute magnitude of 7.11, but at that distance the star has an apparent visual magnitude of 10.16, which is too dim to be visible to the naked eye. The system is receding with a radial velocity of 15.3 km/s, and it has a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.205″·yr−1. The spectrum of HIP 5158 matches an ordinary K-type main-sequence star, an orange dwarf, with a stellar classification of K5V. The age of this star is poorly constrained, but it appears to be comparable to the Sun. It is spinning slowly with a rotation period of around 42.3 days. Based on the abundance of iron, this star appears metal rich, having concentration of heavy elements equal to 125% of solar abundance. It has 75% of the mass of the Sun and 60% of the Sun's radius. The star is radiating just 19% of the luminosity of the Sun from its photosphere at an effective temperature of 4,571 K.

Planetary system In 2009, a gas giant planet HIP 5158 b was found in orbit around the star. The quadratic drift in the radial velocities did indicate the presence of an additional outer planet in the system, which was confirmed in 2011. The large uncertainty in the mass of HIP 5158 c leaves in question whether this is an exoplanet or a brown dwarf.

Worked examples

Example 1 — a first encounter with HIP 5158

Start with the simplest possible case. Write down what HIP 5158 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 HIP 5158 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 HIP 5158 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 HIP 5158

In research: HIP 5158 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 HIP 5158 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: HIP 5158 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Brown dwarfs, Cetus (constellation), Durchmusterung objects, so understanding it makes those chapters shorter.
In everyday life: Look for HIP 5158 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 HIP 5158 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HIP 5158 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 HIP 5158 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HIP 5158 in simple terms?

Why does HIP 5158 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 HIP 5158?

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 HIP 5158.