astronomy

PHL 909

PHL 909 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 909 rather than just read about it. In short: PHL 909 is a low-redshift quasar as well as a Seyfert 1 galaxy located in the constellation of Pisces. The redshift of the object is (z) 0.171, meaning it is located approximately 2.1 billion light-years from Earth.

Key takeaways

PHL 909 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 909 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PHL 909 from memory before moving on to harder problems.

Reference excerpt

PHL 909 is a low-redshift quasar as well as a Seyfert 1 galaxy located in the constellation of Pisces. The redshift of the object is (z) 0.171, meaning it is located approximately 2.1 billion light-years from Earth. It was first discovered in 1978 by astronomers and is classified as radio-quiet.

Description PHL 909 is classified as a normal type E4 elliptical galaxy with a visual magnitude of 15.7. Based on imaging by Hubble Space Telescope, it is described as having a featureless and smooth appearance with the inner region displaying a higher surface brightness on one side. There is also evidence of a tidal bridge between the host and its western companion galaxy, indicating they might be interacting. It appears it also belongs to a galaxy group, given there are several other galaxies within the region, including a large spiral galaxy located at the same redshift. There is also evidence of either ongoing or recent star-formation in the host with a population of old and intermediate stars. It appears PHL 909 is a product of several galaxy mergers. Observation of its structure showed the presence of two shell features located at position angles of 328° and 298°. A ring-like structure is present around the galaxy's nucleus with another ring feature formed by diffuse outer material. There are also two tidal tails in the galaxy, one shown extending from a disk-like structure southeast and the other from a disk northwest. The western tidal tail is extending towards the direction of the companion as well, with it also showing the same tidal tail features. Further evidence also showed the eastern tidal tail is connecting to a dwarf galaxy located 14 arcseconds away from PHL 909. PHL 909 contains hydroxide emission. When studied, the emission is shown to have a signal with a flux density of 60 ± 12 mJy and the isotopic luminosity of the source estimated as 0.8×104 L☉. The galaxy also shows the presence of narrow components in both Balmer and Magnesium emission line profiles, with a small observed redshift of its narrow permitted lines. It is noted there were also changes in these lines between 1980 and 1986, suggesting the production of a narrow Balmer component inside a jet-like structure in the galaxy. A supermassive black hole mass has been estimated as 7.94×108 M☉ based on maser kinematics with a bolometric luminosity of 45.47 erg s−1. Later studies estimated a black hole mass of 3.80+0.56−0.49×108 M☉.

References

External links PHL 909 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images PHL 909 on SIMBAD

Illustrations

Worked examples

Example 1 — a first encounter with PHL 909

Start with the simplest possible case. Write down what PHL 909 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 909 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 909 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 909

In research: PHL 909 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 909 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 909 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Active galaxies, Elliptical galaxies, Galaxy mergers, so understanding it makes those chapters shorter.
In everyday life: Look for PHL 909 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 909 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PHL 909 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 909 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PHL 909 in simple terms?

Why does PHL 909 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 909?

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 909.