astronomy

Innes' star

Innes' star 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 Innes' star rather than just read about it. In short: Innes' star , or Gliese 422, is an M3.5-type red dwarf star, located in the constellation Carina. This star has 36% of the Sun's mass and 37% of the Sun's radius, yet only 1.7% of its luminosity, and an effective temperature of 3,459 K.

Key takeaways

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

Reference excerpt

Innes' star , or Gliese 422, is an M3.5-type red dwarf star, located in the constellation Carina. This star has 36% of the Sun's mass and 37% of the Sun's radius, yet only 1.7% of its luminosity, and an effective temperature of 3,459 K.

Discovery Innes' star was discovered in 1920 by Robert T. A. Innes in Union Observatory, Union of South Africa, who had discerned its large proper motion and a parallax of 0.337 arcsec. The discovery was published in Circular of the Union Observatory No. 49, hence its discovery name is UO 49, or In UOC 49. However, UO designations should be used with caution since they are often not unique for each star: the number in the name is the number of Circular, so all stars published in one Circular have identical names. So, all other newfound stars, published in the 49th Circular, may be named UO 49 too.

Erroneous parallax It is known for the fact that it had once been considered one of the nearest stars to Earth, due to erroneously measured parallax. The estimated distance was less than 10 light-years in the following studies:

In List of stars nearer than 5 parsecs by Ejnar Hertzsprung (1922) its parallax is 0.339 arcsec (distance is 2.95 pc or 9.62 ly), and it is the 4th-closest star system after Alpha Centauri ABC, Barnard's Star and Sirius AB; In A study of the near-by stars by Willem Jacob Luyten and Harlow Shapley (1930) its parallax is 0.337 arcsec (distance is 2.97 pc or 9.68 ly), and it is the 4th-closest star system after Alpha Centauri ABC, Barnard's Star and Lalande 21185 (Sirius is further); In List of stars nearer than five parsecs by Peter van de Kamp (1930) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 7th-closest star system after Alpha Centauri ABC, Barnard's Star, Wolf 359, Lalande 21185, Sirius AB and BD-12 4523; In Stars within ten parsecs of the Sun by Louise Freeland Jenkins (1937) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 6th-closest star system after Alpha Centauri, Barnard's Star, Wolf 359, Lalande 21185 and Sirius. Its actual distance is 12.676 parsecs (41.34 light-years), based on the parallax from Gaia DR3: 0.07889±0.00003 arcsec.

Planetary system In 2014, a sub-Neptune-mass planet, Gliese 422 b, of approximately ten Earth-masses, was discovered around this star. It orbits the star every 20 days and lies at a distance of around 0.11 astronomical units (AU)—11% of the distance between the Earth and Sun—on the inner edge of the stellar system's habitable zone, which for this star has been calculated to lie between 0.11 and 0.21 AU. The discovery of GJ 422 b was confirmed in 2020.

Name Innes' Star is one of a few stars named after people—named after a scientist, whereas the majority of proper names of stars have ancient origins or medieval, in the main Arabic, ones. Certain stars, found to be nearby due to their large proper motion, also fall into this class and are named after their discoverers: Barnard's Star, Kapteyn's Star, Luyten's Star, van Maanen's Star, van Biesbroeck's Star, and Teegarden's Star. Innes is also known as the discoverer of Proxima Centauri.

References

External links Planet GJ 422 b

Worked examples

Example 1 — a first encounter with Innes' star

Start with the simplest possible case. Write down what Innes' star 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 Innes' star 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 Innes' star 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 Innes' star

In research: Innes' star 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 Innes' star 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: Innes' star is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1920, Carina (constellation), Discoveries by Robert T. A. Innes, so understanding it makes those chapters shorter.
In everyday life: Look for Innes' star 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 “Innes' star” →

Affiliate

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

How to study Innes' star in 20 minutes

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

Frequently asked questions

What is Innes' star in simple terms?

Why does Innes' star 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 Innes' star?

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 Innes' star.