astronomy

PHL 293B

PHL 293B 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 PHL 293B rather than just read about it. In short: PHL 293B, also known as Kinman's dwarf, is a low-metallicity blue compact dwarf galaxy about 23.15 megaparsecs (75.51 million light-years) from the Earth in the constellation Aquarius. It had a very likely associated, notable, blue-light, long-lived star with constant outbursts or a large supernova observed to have faded and which then disappeared.

Key takeaways

PHL 293B belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PHL 293B to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PHL 293B from memory before moving on to harder problems.

Reference excerpt

PHL 293B, also known as Kinman's dwarf, is a low-metallicity blue compact dwarf galaxy about 23.15 megaparsecs (75.51 million light-years) from the Earth in the constellation Aquarius. It had a very likely associated, notable, blue-light, long-lived star with constant outbursts or a large supernova observed to have faded and which then disappeared. Although this bright visible jet-producing object responsible for broad hydrogen emission lines with P Cygni profiles was widely considered to be a luminous blue variable ejecting matter, other studies posited the mentioned, competing, explanations for the bright light source within.

Observation history PHL 293 was first listed as entry 293 in a catalogue of faint blue stars published by Guillermo Haro and Willem Jacob Luyten in 1962. In 1965, Thomas Kinman observed two faint possible companions to it, about 1′ away, which he dubbed A and B. HL 293B, sometimes called Kinman's Dwarf, was noted to be an extragalactic, nonstellar object, with a jet, approximately 22.6 Mpc away from Earth. The acronym PHL has since been applied to distinguish it from other HL catalogues; it is most commonly referred to by astronomers as PHL 293B. The galaxy was identified as a blue compact dwarf, a type of small irregular galaxy undergoing a strong burst of star formation. The spectrum of PHL 293B is unusual both for its low metallicity and for broad hydrogen emission lines with P Cygni profiles. These are interpreted as being from a large luminous blue variable star in the galaxy. The star is believed to have been undergoing an outburst during previous observations, an interpretation is disputed by some publications. An alternative explanation would be a long-lived type IIn supernova, similar to the transient event of SDSS1133. These emission features in the spectrum of the galaxy faded during 2019 and by the end of the year had disappeared (at least visibly), likely due to the disappearance of a bright star of the galaxy.

See also AG Carinae Markarian 177 LBV 1806-20 Eta Carinae

Notes

References

Illustrations

Worked examples

Example 1 — a first encounter with PHL 293B

Start with the simplest possible case. Write down what PHL 293B 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 PHL 293B 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 PHL 293B 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 PHL 293B

In research: PHL 293B 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 PHL 293B 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: PHL 293B is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aquarius (constellation), Dwarf galaxies, Luminous blue variables, so understanding it makes those chapters shorter.
In everyday life: Look for PHL 293B 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 PHL 293B in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PHL 293B 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 PHL 293B out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PHL 293B in simple terms?

Why does PHL 293B 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 PHL 293B?

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 PHL 293B.