astronomy

Hen 2-10

Hen 2-10 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 Hen 2-10 rather than just read about it. In short: Hen 2-10, also known as He 2-10 and Henize 2-10, is a dwarf starburst galaxy located 34 million light years away in the constellation of Pyxis. The galaxy is believed to be an early stage starburst galaxy.

Key takeaways

Hen 2-10 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hen 2-10 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hen 2-10 from memory before moving on to harder problems.

Reference excerpt

Hen 2-10, also known as He 2-10 and Henize 2-10, is a dwarf starburst galaxy located 34 million light years away in the constellation of Pyxis. The galaxy is believed to be an early stage starburst galaxy. A black hole was later discovered near the center of the dwarf galaxy, suggesting that the black holes found at the center of most large galaxies may have formed before the galaxies themselves. Recent estimates have placed the mass of this black hole around 3×106 M☉, and the mass of the entire dwarf galaxy at about 1×1010 M☉.

History Henize 2-10 draws its name from a catalog of planetary nebulae assembled by astronomer Karl Henize. Henize additionally noted that the object was identified in an unpublished paper by Rudolph Minkowski. The object was likely misidentified as a planetary nebula due to the galaxy's strong emission lines, a feature common of planetary nebulas. It was not until the 1970s when observations of Hen 2-10 indicated that the center of the object was a strong source of radio waves that it was shown that Hen 2-10 was a dwarf galaxy rather than a planetary nebula. Supporting evidence for the reclassification came in the form of excess infrared emission and a higher than usual density of neutral hydrogen.

Structure Hen 2-10 is a starburst galaxy featuring at least two star-forming regions near the center of the galaxy. These regions feature a variety of different substances, and multiple super star clusters. A study of some of these SSCs estimates their age to be between 4 and 5 megayears. The galaxy also features emission typical of that in a Wolf–Rayet star, further providing evidence for the starburst region of the galaxy. It was one of the first galaxies found to feature this emission. The strong prevalence of this emission has led to its classification as a Wolf–Rayet galaxy, a special subclass of starburst galaxy that features a higher than normal number of Wolf–Rayet stars. Furthermore, observations have shown irregularities in the southeast portion of the galaxy which could be interpreted as a tidal tail. This tidal tail suggests that Hen 2-10 may have had past interactions with other galaxies, possibly even a merger event.

Central black hole In 2011, a team of researchers studied the non-thermal emission of the galaxy center and indicated that the source strengths of radio waves are too strong to come from x-ray binaries while the source strengths of x-rays are too strong to be supernova remnants. However, these sources do align with known data for black holes. This original paper postulated the mass of the black hole to be ~1×106 M☉, but a newer study has refined the estimate to 3×106 M☉. The presence of SSCs near the center of the galaxy, and not a singular nuclear star cluster (NSC) has led some to believe that Hen 2-10 is a galaxy in its early years. The presence of the black hole is seen to be evidence of the dissipationless model of NSC formation. In this model, the SSCs will move to the center and form a singular NSC. Due to the black hole's relatively small mass, it is not believed to have a major effect on the timescale of this motion, although it is not yet understood how the black hole will affect the NSC formation. Ignoring the black hole indicates that the NSC should be fully formed in a few hundred million years.

References

Illustrations

Worked examples

Example 1 — a first encounter with Hen 2-10

Start with the simplest possible case. Write down what Hen 2-10 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 Hen 2-10 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 Hen 2-10 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 Hen 2-10

In research: Hen 2-10 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 Hen 2-10 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: Hen 2-10 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Dwarf galaxies, Principal Galaxies Catalogue objects, Pyxis, so understanding it makes those chapters shorter.
In everyday life: Look for Hen 2-10 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 Hen 2-10 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hen 2-10 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 Hen 2-10 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hen 2-10 in simple terms?

Why does Hen 2-10 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 Hen 2-10?

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 Hen 2-10.