astronomy

Messier 62

Messier 62 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 Messier 62 rather than just read about it. In short: Messier 62 or M62, also known as NGC 6266 or the Flickering Globular Cluster, is a globular cluster of stars located in the south of the constellation of Ophiuchus. The cluster was discovered on 7 June 1771 by Charles Messier, who listed it as the 62nd entry in his catalogue published eight years later.

Key takeaways

Messier 62 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Messier 62 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Messier 62 from memory before moving on to harder problems.

Reference excerpt

Messier 62 or M62, also known as NGC 6266 or the Flickering Globular Cluster, is a globular cluster of stars located in the south of the constellation of Ophiuchus. The cluster was discovered on 7 June 1771 by Charles Messier, who listed it as the 62nd entry in his catalogue published eight years later. M62 is about 21.5 kly from Earth and 5.5 kly from the Galactic Center. It is among the most massive and luminous globular clusters in the Milky Way: its estimated mass is 1.22×106 M☉, its integrated absolute magnitude in the V band is −9.18., and therefore the mass-to-light ratio is 2.05±0.04. It has a projected ellipticity of 0.01, meaning it is essentially spherical. The density profile of its member stars suggests it has not yet undergone core collapse. It has a core radius of 1.3 ly (0.39 pc), a half-mass radius of 9.6 ly (2.95 pc), and a half-light radius of 6.0 ly (1.83 pc). The stellar density at the core is 5.13 M☉ per cubic parsec. It has a tidal radius of 59 ly (18.0 pc). The cluster shows at least two distinct populations of stars, which most likely represent two separate episodes of star formation. Of the main sequence stars in the cluster, 79%±1% are from the first generation and 21%±1% from the second. The second is enriched by elements released by the first. In particular, abundances of helium, carbon, magnesium, aluminium, and sodium differ between these two. Indications are this is an Oosterhoff type I, or "metal-rich" system. A 2010 study identified 245 variable stars in the cluster's field, of which 209 are RR Lyrae variables, four are Type II Cepheids, 25 are long period variables, and one is an eclipsing binary. The cluster may prove to be the galaxy's richest in terms of RR Lyrae variables. It has ten binary millisecond pulsars, including one (M62B) that is displaying eclipsing behavior from gas streaming off its companion, and one (M62H) with an orbiting exoplanet about three times the mass of Jupiter. There are multiple X-ray sources, including 50 within the half-mass radius. 47 blue straggler candidates have been identified, formed from the merger of two stars in a binary system, and these are preferentially concentrated near the core region. It is hypothesized that this cluster may be host to an intermediate mass black hole (IMBH) – it is considered well-suited for searching for such an object. A brief study, before 2013, of the proper motion of stars within 17″ of the core did not require an IMBH to explain. However, simulations can not rule out one with a mass of a few thousand M☉ in M62's core. For example, based upon radial velocity measurements within an arcsecond of the core, Kiselev et al. (2008) made the claim of an IMBH in M15, likewise with mass of (1–9)×103 M☉.

Gallery

Illustrations

Worked examples

Example 1 — a first encounter with Messier 62

Start with the simplest possible case. Write down what Messier 62 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 Messier 62 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 Messier 62 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 Messier 62

In research: Messier 62 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 Messier 62 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: Messier 62 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1771, Discoveries by Charles Messier, Globular clusters, so understanding it makes those chapters shorter.
In everyday life: Look for Messier 62 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 Messier 62 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Messier 62 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 Messier 62 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Messier 62 in simple terms?

Why does Messier 62 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 Messier 62?

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 Messier 62.