astronomy

OJ 508

OJ 508 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 OJ 508 rather than just read about it. In short: OJ 508 also known as SBS 0804+499, is a quasar located in the constellation of Lynx. The redshift of the quasar is estimated to be (z) 1.434 and it was first discovered as an astronomical radio source in 1981 by astronomers.

Key takeaways

OJ 508 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OJ 508 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OJ 508 from memory before moving on to harder problems.

Reference excerpt

OJ 508 also known as SBS 0804+499, is a quasar located in the constellation of Lynx. The redshift of the quasar is estimated to be (z) 1.434 and it was first discovered as an astronomical radio source in 1981 by astronomers. The radio spectrum of the quasar is estimated to be flat, making it a flat-spectrum radio quasar.

Description The radio source of OJ 508 is compact. When observed with Very Long Baseline Interferometry (VLBI), the source has an asymmetrical complicated radio structure made up of an unresolved component and weak extended structure that is located in the southeast region. Further observations found there are multiple components displaying superluminal motion. In addition, the quasar has a broad radio jet travelling southeast from east direction, reaching about one to three milliarcseconds. Imaging made at 22 Hz, showed this jet has a twisted appearance. The radio core of the quasar is only 0.15 milliarcseconds in extent, with the presence of extended radio emission east. OJ 508 is described as a highly polarized quasar (HPQ). The quasar has polarization levels ranging between 8.6% up to 11.3%. It is variable on a short measured timescale which lasted around 22 days. An outburst was detected from the quasar, beginning in 1997 and ending at the end of the monitoring period. The modulation index of the quasar was observed rising 18% at various wavelengths before declining 14% when observed at 1.3 centimeter wavelengths. High amplitude variability was observed, increasing to 35% in April 1990. The host galaxy of OJ 508 has been classified as unresolved, but has a faint tidal tail extension that is expanding by 3.5 arcseconds north from the quasar, and also in off-center direction. This is possibly a recent sign of a tidal interaction. Later, when observed in 2010, it was found the disturbed morphology of the quasar isn't related to any interactions. A faint galaxy is 10 arcseconds away from the quasar.

References

External links

OJ 508 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images OJ 508 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with OJ 508

Start with the simplest possible case. Write down what OJ 508 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 OJ 508 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 OJ 508 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 OJ 508

In research: OJ 508 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 OJ 508 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: OJ 508 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Astronomical objects discovered in 1981, LEDA objects, so understanding it makes those chapters shorter.
In everyday life: Look for OJ 508 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 OJ 508 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OJ 508 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 OJ 508 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OJ 508 in simple terms?

Why does OJ 508 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 OJ 508?

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 OJ 508.