astronomy

HD 8673

HD 8673 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 HD 8673 rather than just read about it. In short: HD 8673 is a binary star in the northern constellation of Andromeda. It has an apparent magnitude and absolute magnitude of 6.34 and 3.56 respectively.

Key takeaways

HD 8673 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HD 8673 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HD 8673 from memory before moving on to harder problems.

Reference excerpt

HD 8673 is a binary star in the northern constellation of Andromeda. It has an apparent magnitude and absolute magnitude of 6.34 and 3.56 respectively. Based upon an annual parallax shift of 26.2 mas, the system is located around 124.5 light years away. The system is moving further from the Earth with a heliocentric radial velocity of +19 km/s. A sub-stellar companion was detected in 2005; it could either be an exoplanet or a brown dwarf. The primary component is an F-type main-sequence star with a stellar classification of F7 V. It has 1.36 times the mass of the Sun and 1.52 times the Sun's radius. The star is around 1.5 billion years old and is spinning with a projected rotational velocity of 26.9 km/s. It is radiating 3.4 times the Sun's luminosity from its photosphere at an effective temperature of 6,340 K. Speckle interferometry measurements of this star between 2001 and 2008 showed a candidate stellar companion to this star, announced in 2011. It was unclear whether the pair formed a visual double or a binary system. The authors of the study estimated a class of K2 V, based upon a visual magnitude difference of 2.3±0.5. Subsequent observations using adaptive options did not spot this companion and it was concluded this was a false detection. However, a low mass stellar companion was detected in a wide orbit. This red dwarf star has 0.33–0.45 times the mass of the Sun and is orbiting with a semimajor axis of 35–60 AU.

Planetary system An orbiting sub-stellar companion with a minimum mass 14 times that of Jupiter in a high-eccentricity orbit was discovered in 2005 and confirmed in 2010. This object orbits at 3 AU away from the primary star with a period of 1,634 days and an eccentricity of 0.7. In 2022, the inclination and true mass of HD 8673 Ab were measured via astrometry.

References

External links "Notes for planet HD 8673 b". Extrasolar Planets Encyclopaedia. Archived from the original on September 21, 2010. Retrieved December 21, 2007. Hatzes; et al. (2005). "The first extrasolar planets from the TOPS program: a superplanet around a massive evolved star and an F7 star" (PDF). Geophysical Resource Abstract. 7. Retrieved December 21, 2007.

Worked examples

Example 1 — a first encounter with HD 8673

Start with the simplest possible case. Write down what HD 8673 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 HD 8673 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 HD 8673 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 HD 8673

In research: HD 8673 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 HD 8673 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: HD 8673 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Andromeda (constellation), Binary stars, Bright Star Catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for HD 8673 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 HD 8673 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HD 8673 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 HD 8673 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HD 8673 in simple terms?

HD 8673 is a binary star in the northern constellation of Andromeda. It has an apparent magnitude and absolute magnitude of 6.34 and 3.56 respectively.

Why does HD 8673 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 HD 8673?

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 HD 8673.