astronomy

RX J1242−11

RX J1242−11 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 RX J1242−11 rather than just read about it. In short: RX J1242.6−1119A (often abbreviated RX J1242−11) is an elliptical galaxy located approximately 200 megaparsecs (about 650 million light-years) from Earth. The name is derived from RX J1242.6-1119, the term for an X-ray source identified by ROSAT as a galaxy pair [KG99] A & B.

Key takeaways

RX J1242−11 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect RX J1242−11 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of RX J1242−11 from memory before moving on to harder problems.

Reference excerpt

RX J1242.6−1119A (often abbreviated RX J1242−11) is an elliptical galaxy located approximately 200 megaparsecs (about 650 million light-years) from Earth. The name is derived from RX J1242.6-1119, the term for an X-ray source identified by ROSAT as a galaxy pair [KG99] A & B.

Supermassive black hole

According to current interpretations of X-ray observations made by the Chandra X-ray Observatory and XMM-Newton, the center of this galaxy is a 100 million solar mass supermassive black hole which was observed to have tidally disrupted a star (in 1992 or shortly before). The discovery is widely considered to be the first strong evidence of a supermassive black hole ripping apart a star and consuming a portion of it.

Location in the sky The location of RX J1242.6-1119A, as seen from Earth, is less than one degree to the northeast of Messier 104, the Sombrero Galaxy.

References

External links Media related to RX J1242-11 at Wikimedia Commons

Komossa's Object Chandra X-Ray Observatory Photo Album – February 18, 2004 Auchettl, Katie; Guillochon, James; Ramirez-Ruiz, Enrico (4 April 2017). "New Physical Insights about Tidal Disruption Events from a Comprehensive Observational Inventory at X-Ray Wavelengths". The Astrophysical Journal. 838 (2): 149. arXiv:1611.02291. Bibcode:2017ApJ...838..149A. doi:10.3847/1538-4357/aa633b.

Illustrations

Worked examples

Example 1 — a first encounter with RX J1242−11

Start with the simplest possible case. Write down what RX J1242−11 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 RX J1242−11 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 RX J1242−11 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 RX J1242−11

In research: RX J1242−11 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 RX J1242−11 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: RX J1242−11 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Elliptical galaxies, ROSAT objects, Virgo (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for RX J1242−11 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 RX J1242−11 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what RX J1242−11 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 RX J1242−11 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is RX J1242−11 in simple terms?

Why does RX J1242−11 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 RX J1242−11?

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 RX J1242−11.