astronomy

Pisces II

Pisces II 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 Pisces II rather than just read about it. In short: Pisces II (Psc II) is an ultra-faint dwarf-spheroidal galaxy and satellite of the Milky Way, located in the Pisces constellation 180 kpc (587,081 light years) from Earth. Discovered in 2009 by public analysis of Data Release 7 (DR7) of the Sloan Digital Sky Survey, it is classified as a dwarf spheroidal galaxy (dSph) and is one of the smallest and faintest satellite galaxies of the Milky Way.

Key takeaways

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

Reference excerpt

Pisces II (Psc II) is an ultra-faint dwarf-spheroidal galaxy and satellite of the Milky Way, located in the Pisces constellation 180 kpc (587,081 light years) from Earth. Discovered in 2009 by public analysis of Data Release 7 (DR7) of the Sloan Digital Sky Survey, it is classified as a dwarf spheroidal galaxy (dSph) and is one of the smallest and faintest satellite galaxies of the Milky Way.

Structure Pisces is a small irregular galaxy, with a moderately-aged and older stellar population of metal-poor stars, consisting primarily of stars formed about 10 billion years ago. The metallicity of these old stars is low, at −2.3 < [Fe/H] < −1.7, which means that the ratio of their mass that consists of heavy metals is less than that of the Sun. Its luminosity is about 10,000 times that of the Sun (absolute magnitude of about −5), which corresponds to the luminosity of an average globular cluster.

Potential past interactions In 2016, follow-up work on Pisces II and Pegasus III highlighted that both lie relatively close to each other (within approximately 43 kiloparsecs), and share similar radial velocities in the Milky Way's rest frame. This suggests that these two satellite galaxies may actually be associated with one another, potentially having interacted in the past; however, further spectroscopic measurements are needed to confirm this.

See Also Satellite galaxies of the Milky Way Pisces VII, a dwarf satellite galaxy of the Triangulum galaxy Pisces A and Pisces B, two void dwarf galaxies in the Local Group

Notes

References

Further reading Sand, David J; Strader, Jay; Willman, Beth; Zaritsky, Dennis; McLeod, Brian; Caldwell, Nelson; Seth, Anil; Olszewski, Edward (2012). "Tidal Signatures in the Faintest Milky Way Satellites: The Detailed Properties of Leo V, Pisces Ii, and Canes Venatici Ii". The Astrophysical Journal. 756 (1): 79. arXiv:1111.6608. Bibcode:2012ApJ...756...79S. doi:10.1088/0004-637X/756/1/79. S2CID 46030862.

Worked examples

Example 1 — a first encounter with Pisces II

Start with the simplest possible case. Write down what Pisces II 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 Pisces II 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 Pisces II 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 Pisces II

In research: Pisces II 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 Pisces II 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: Pisces II is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2010, Dwarf spheroidal galaxies, Local Group, so understanding it makes those chapters shorter.
In everyday life: Look for Pisces II 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 Pisces II in 20 minutes

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

Frequently asked questions

What is Pisces II in simple terms?

Why does Pisces II 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 Pisces II?

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 Pisces II.