astronomy

LS I +61 303

LS I +61 303 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 LS I +61 303 rather than just read about it. In short: LS I +61 303 is a binary system containing a massive star and a compact object. The compact object is a pulsar and the system is around 7,000 light-years away.

Key takeaways

LS I +61 303 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LS I +61 303 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LS I +61 303 from memory before moving on to harder problems.

Reference excerpt

LS I +61 303 is a binary system containing a massive star and a compact object. The compact object is a pulsar and the system is around 7,000 light-years away.

Discovery LS I +61 303 is an 11th-magnitude star that was recognised as a luminous object and catalogued as an OB star in 1959. It was included in the Hipparcos survey as HIP 12469 and had its parallax measured at 5.65±2.28 milliarcseconds (mas), revised to −0.29±2.99 mas in the new reduction. The third Gaia data release gave a parallax of 0.38±0.01 mas. The Galactic radio source GT 0236+610 was found at the same position as LS I +61 303. A gamma-ray source 2CG 135+01 was found within a degree of its position, and the MAGIC telescope confirmed that LS I +61 303 was the source of the gamma rays. Periodic X-ray outbursts also occur.

Binary system

LS I +61 303 shows the spectrum of a Be star, a B0 main sequence star with disk that produces emission lines in its spectrum. Variations in its radial velocity show that it is in orbit with an unseen compact object having a mass between 1 and 4 M☉. The pair orbit every 26.496 days. Although the uncertain mass of the compact object would allow it to be a neutron star, it was often suggested to be a black hole. In March 2022, a period of ~0.27 s was reported to be detected in observations using the FAST telescope, confirming the neutron star nature of the compact object. This promotes the possibility that the system is indeed the first one detected containing a pulsar with magnetar behavior in it.

Variability In 1979, Philip C. Gregory et al. discovered that the star's brightness varies, after examining decades of Harvard College Observatory photographic plates. LS I +61 303 varies slightly at optical wavelengths, but measurements going back to 1887 show no obvious period. It also shows regular X-ray outbursts coinciding with its orbital period, and strong radio variability. It was given the variable star designation V615 Cassiopeiae.

Microquasar LS I +61 303 emits HE and VHE (High Energy and Very High Energy) gamma rays. It is only one of several known star systems that produce such energetic rays. Other such systems are PSR B1259–63, LS 5039 and HESS J0632+057.

References

External links Astronomers Discovery Very High Energy Gamma-ray Emission From Microquasar (ScienceDaily) May 19, 2006 MAGIC – Major Atmospheric Gamma Imaging Cerenkov Telescope MAGIC Telescope home page TeV gamma ray source catalog home page

Worked examples

Example 1 — a first encounter with LS I +61 303

Start with the simplest possible case. Write down what LS I +61 303 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 LS I +61 303 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 LS I +61 303 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 LS I +61 303

In research: LS I +61 303 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 LS I +61 303 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: LS I +61 303 is common in secondary-school and first-year university syllabi. It links to neighbouring topics B-type main-sequence stars, Be stars, Cassiopeia (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for LS I +61 303 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 LS I +61 303 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LS I +61 303 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 LS I +61 303 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LS I +61 303 in simple terms?

LS I +61 303 is a binary system containing a massive star and a compact object. The compact object is a pulsar and the system is around 7,000 light-years away.

Why does LS I +61 303 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 LS I +61 303?

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 LS I +61 303.