astronomy

PKS 0208−512

PKS 0208−512 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 PKS 0208−512 rather than just read about it. In short: PKS 0208−512 is a blazar located in the southern constellation of Eridanus. It has a redshift of 1.003 and was first discovered in 1975 by astronomers conducting the Parkes 2700 MHz survey in Australia as a bright astronomical radio source.

Key takeaways

PKS 0208−512 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PKS 0208−512 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PKS 0208−512 from memory before moving on to harder problems.

Reference excerpt

PKS 0208−512 is a blazar located in the southern constellation of Eridanus. It has a redshift of 1.003 and was first discovered in 1975 by astronomers conducting the Parkes 2700 MHz survey in Australia as a bright astronomical radio source. This object is also classified highly polarized with the radio spectrum appearing to be flat, thus making it a flat-spectrum radio quasar.

Description PKS 0208−512 is found to be strongly variable on the electromagnetic spectrum. It shows a significant correlation between its intensity and spectral index, and is a source of gamma ray activity. It is known to have three powerful outbursts when observed at optical to near-infrared wavelengths. Between September 11 and 30 in 2008, the quasar brightened upon showing a flare, with increased magnitudes in both B-band and R-band. In the gamma ray lightcurve, it showed a variable flux reaching a factor of 6 on timescales of weeks. A major gamma ray flare was detected in PKS 0208−512 between November 2019 and May 2020. Fermi-LAT observations proposed that its daily average gamma ray flux at > 100 MeV amplified to (1.1±0.2)×10−6 ph cm−2 s−1 on November 29, 2019, and subsequently to (2.0±0.3)×10−6 photons cm−2 s−1 by March 15, 2020. During the activity, the gamma ray lightcurve exhibited multiple peaks indicating the presence of subflares. PKS 0208−512 has a complex radio structure. It is made up of a compact radio core with a projected spectral flux density of 2.8 Jansky and a jet component located at a position angle of 234° from the core with an angular separation of 1.7 mas. Using 2.3 and 5.0 GHz results, the core has a spectral index of 0.15, as well as having an obtained brightness temperature of 1.9 trillion K. There is also a long jet present at a position angle of −129°. This jet is found similar to the milliarcsecond-scale radio jet's position angle, suggesting it is straight from parsec to kiloparsec scales. When seen through the jet's structure, there are four knot regions which increases orderly from the nucleus. The supermassive black hole in PKS 0208−512 is estimated to be 6×107 M☉ based on an assumption of its isotopic Eddington-limited emission. A luminosity of Ld ≈ 8×1045 erg/s was estimated for its accretion disk.

References

External links PKS 0208−512 on SIMBAD PKS 0208−512 on NASA/IPAC Database

Illustrations

Worked examples

Example 1 — a first encounter with PKS 0208−512

Start with the simplest possible case. Write down what PKS 0208−512 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 PKS 0208−512 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 PKS 0208−512 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 PKS 0208−512

In research: PKS 0208−512 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 PKS 0208−512 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: PKS 0208−512 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Astronomical objects discovered in 1975, BL Lacertae objects, so understanding it makes those chapters shorter.
In everyday life: Look for PKS 0208−512 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 PKS 0208−512 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PKS 0208−512 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 PKS 0208−512 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PKS 0208−512 in simple terms?

Why does PKS 0208−512 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 PKS 0208−512?

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 PKS 0208−512.