astronomy

SDSS J090745.0+024507

SDSS J090745.0+024507 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 SDSS J090745.0+024507 rather than just read about it. In short: SDSS J090744.99+024506.8 (SDSS 090745.0+024507) is a short-period variable star in the constellation Hydra. It has a Galactic rest-frame radial velocity of 709 km/s.

Key takeaways

SDSS J090745.0+024507 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SDSS J090745.0+024507 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SDSS J090745.0+024507 from memory before moving on to harder problems.

Reference excerpt

SDSS J090744.99+024506.8 (SDSS 090745.0+024507) is a short-period variable star in the constellation Hydra. It has a Galactic rest-frame radial velocity of 709 km/s. Its effective temperature is 10,500 K (corresponding to a spectral type of B9) and its age is estimated to be at most 350 million years. It has a heliocentric distance of 71 kpc. It was ejected from the centre of the galaxy less than 100 million years ago, which implies the existence of a population of young stars at the galactic centre less than 100 million years ago. Christened by the astronomer Warren Brown as the "outcast star", it is the first discovered member of a class of objects named hypervelocity stars. It was discovered in 2005 at the MMT Observatory of the Center for Astrophysics | Harvard & Smithsonian (CfA), by astronomers Warren Brown, Margaret J. Geller, Scott J. Kenyon and Michael J. Kurtz.

See also List of star extremes S5-HVS1 – another fast moving star US 708 – another fast moving star

References

Further reading Gualandris, Alessia; Portegies Zwart, Simon & Sipior, Michael S. (2005), "Three-body encounters in the Galactic Centre: the origin of the hypervelocity star SDSS J090745.0+024507", Monthly Notices of the Royal Astronomical Society, 363 (1): 223–228, arXiv:astro-ph/0507365, Bibcode:2005MNRAS.363..223G, doi:10.1111/j.1365-2966.2005.09433.x, S2CID 15437038 Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. & Kurtz, Michael J. (2006), "A Successful Targeted Search for Hypervelocity Stars", Astrophysical Journal, 640 (1): L35–L38, arXiv:astro-ph/0601580, Bibcode:2006ApJ...640L..35B, doi:10.1086/503279, S2CID 17220212 Fuentes, Cesar I.; Stanek, K. Z.; Gaudi, B. Scott; et al. (2006), "The Hypervelocity Star SDSS J090745.0+024507 Is Variable", Astrophysical Journal, 636 (1): L37–L40, arXiv:astro-ph/0507520, Bibcode:2006ApJ...636L..37F, doi:10.1086/499233, S2CID 14266685 Bromley, Benjamin C.; Kenyon, Scott J.; Geller, Margaret J.; et al. (2006), "Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities", Astrophysical Journal, 653 (2): 1194–1202, arXiv:astro-ph/0608159, Bibcode:2006ApJ...653.1194B, doi:10.1086/508419, S2CID 16202860

External links Press release First Stellar Outcast Speeding at Over 1.5 Million Miles Per Hour (PhysOrg.com)

Illustrations

Worked examples

Example 1 — a first encounter with SDSS J090745.0+024507

Start with the simplest possible case. Write down what SDSS J090745.0+024507 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 SDSS J090745.0+024507 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 SDSS J090745.0+024507 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 SDSS J090745.0+024507

In research: SDSS J090745.0+024507 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 SDSS J090745.0+024507 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: SDSS J090745.0+024507 is common in secondary-school and first-year university syllabi. It links to neighbouring topics B-type main-sequence stars, Hydra (constellation), Hypervelocity stars, so understanding it makes those chapters shorter.
In everyday life: Look for SDSS J090745.0+024507 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 SDSS J090745.0+024507 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SDSS J090745.0+024507 means in your own words.
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Work through the three examples above with pen and paper.
Explain SDSS J090745.0+024507 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SDSS J090745.0+024507 in simple terms?

SDSS J090744.99+024506.8 (SDSS 090745.0+024507) is a short-period variable star in the constellation Hydra. It has a Galactic rest-frame radial velocity of 709 km/s.

Why does SDSS J090745.0+024507 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 SDSS J090745.0+024507?

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 SDSS J090745.0+024507.