astronomy

HE 1523−0901

HE 1523−0901 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 HE 1523−0901 rather than just read about it. In short: HE 1523−0901 is the designation given to an ancient red giant star in the Milky Way galaxy approximately 9,900 light-years from Earth. It is thought to be a second generation, Population II, or metal-poor, star ([Fe/H] = −2.95).

Key takeaways

HE 1523−0901 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HE 1523−0901 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HE 1523−0901 from memory before moving on to harder problems.

Reference excerpt

HE 1523−0901 is the designation given to an ancient red giant star in the Milky Way galaxy approximately 9,900 light-years from Earth. It is thought to be a second generation, Population II, or metal-poor, star ([Fe/H] = −2.95). The star was found in the sample of bright metal-poor halo stars from the Hamburg/ESO Survey by Anna Frebel and collaborators. The group's research was published in the May 10, 2007 issue of The Astrophysical Journal.

Age The star's age, as measured by ESO's Very Large Telescope, is 13.2 billion years. This makes it among the oldest stars and nearly as old as the estimated age of the universe itself (13.8 billion years as measured by Planck). The measurement uncertainty in the age estimate is 0.7 to 2.7 billion years, depending upon the assumptions made to estimate the uncertainty, although the uncertainty in the relative age of this and other stars using the same method is smaller. HE 1523−0901 is the first star whose age was determined using the decay of the radioactive elements uranium and thorium in tandem with measurements of several neutron capture elements. It is believed to have formed directly from the remnants of the first-generation stars that reached the end of their longevity and exploded as supernovae early in the history of known matter.

Designation The designation "HE 1523−0901" indicates that the star is part of the Hamburg/ESO Survey catalog. A list of astronomical catalogues can be used to find which catalog a star or other object is from based on its prefix. Most objects are listed in several catalogs and will often be known by several different designations.

Observation HE 1523−0901 is approximately 0.8 solar masses, but the star has expanded until it is some 27 times as large, and has a total luminosity of 730 times that of the Sun. It can be viewed particularly well from the southern hemisphere with the use of a small telescope. It can also be observed from central European latitudes.

Spectroscopic companion HE 1523−0901 was found to be a spectroscopic binary by a 2015 study. The companion has a minimum mass about 11 times the mass of Jupiter, suggesting that it may be a brown dwarf or massive exoplanet. However, the discovery paper suggests that the companion's orbit may be nearly face-on, which would make the true mass much greater than the minimum mass, at about a quarter the mass of the Sun. Such an object would be a red dwarf star. The orbital inclination and thus true mass is not yet known with certainty.

See also HD 140283 Sneden's Star Gaia BH3

References

External links "Astronomers discover HE 1523-0901 star: Almost as old as universe". iTWire. Archived from the original on 2007-05-14. Retrieved 2007-05-15. "Ancient star nearly as old as the universe". NBC News. 11 May 2007. Archived from the original on March 5, 2016. Retrieved 2007-05-14.

Illustrations

Worked examples

Example 1 — a first encounter with HE 1523−0901

Start with the simplest possible case. Write down what HE 1523−0901 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 HE 1523−0901 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 HE 1523−0901 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 HE 1523−0901

In research: HE 1523−0901 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 HE 1523−0901 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: HE 1523−0901 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Giant stars, Libra (constellation), Population II stars, so understanding it makes those chapters shorter.
In everyday life: Look for HE 1523−0901 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 HE 1523−0901 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HE 1523−0901 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 HE 1523−0901 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HE 1523−0901 in simple terms?

Why does HE 1523−0901 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 HE 1523−0901?

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 HE 1523−0901.