astronomy

GJ 1151

GJ 1151 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 GJ 1151 rather than just read about it. In short: GJ 1151 is a star located in the northern circumpolar constellation of Ursa Major at a distance of 26.2 light-years (8.0 parsecs) from the Sun. It has a reddish hue and is too faint to be visible to the naked eye with an apparent visual magnitude of 14.0.

Key takeaways

GJ 1151 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GJ 1151 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GJ 1151 from memory before moving on to harder problems.

Reference excerpt

GJ 1151 is a star located in the northern circumpolar constellation of Ursa Major at a distance of 26.2 light-years (8.0 parsecs) from the Sun. It has a reddish hue and is too faint to be visible to the naked eye with an apparent visual magnitude of 14.0. The star is moving closer with a radial velocity of −36 km/s, and has a relatively large proper motion, traversing the celestial sphere at a rate of 1.815″·yr−1. This is a small red dwarf star of spectral type dM4.5. It is 2.5 billion years old and is spinning with a projected rotational velocity of 2.0 km/s. The star has 15.4% of the mass of the Sun and 19.0% of the Sun's radius, with an effective temperature of 3,143 K.

Planetary system In 2020, astronomers announced the discovery of radio emissions from the star which are consistent with the star having a magnetic interaction with a planet approximately the size of Earth, revolving in a 1-5 day long orbit. Such an interaction would be analogous to a scaled-up version of the Jupiter-Io magnetic interaction, with GJ 1151 taking the role of Jupiter and its planet the role of Io. Two papers published only a month apart in 2021 discussed planet detection at GJ 1151 by the radial velocity method. One claimed the detection of a planet with a minimum mass of 2.5 M🜨 and a period of 2 days, supporting the radio emission detection, while the other was unable to confirm this candidate planet, finding that the 2-day signal is likely caused by long-term variability, possibly connected to a more distant planet. This second study placed an upper limit of 0.7-1.2 M🜨 on the minimum masses of any undetected planets with periods from 1-5 days. In 2023, a different planet was found, with a minimum mass of 10.6 M🜨 and a 390-day orbit, along with additional radial velocity variations. This new planet was referred to by the preprint version of the discovery paper as GJ 1151 b, but the published version of the paper, as well as the NASA Exoplanet Archive, refer to it as GJ 1151 c to differentiate it from the previous candidate. While the presence of a short-period planet associated with the radio emissions could not be completely ruled out, if such a planet exists its minimum mass must be less than 1.2 M🜨.

See also List of star systems within 20–25 light-years

References

Illustrations

Worked examples

Example 1 — a first encounter with GJ 1151

Start with the simplest possible case. Write down what GJ 1151 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 GJ 1151 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 GJ 1151 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 GJ 1151

In research: GJ 1151 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 GJ 1151 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: GJ 1151 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Gliese and GJ objects, M-type main-sequence stars, Planetary systems with one confirmed planet, so understanding it makes those chapters shorter.
In everyday life: Look for GJ 1151 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 “GJ 1151” →

Affiliate

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

How to study GJ 1151 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GJ 1151 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 GJ 1151 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GJ 1151 in simple terms?

Why does GJ 1151 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 GJ 1151?

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 GJ 1151.