astronomy

Ross 248

Ross 248 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 Ross 248 rather than just read about it. In short: Ross 248, also called HH Andromedae or Gliese 905, is a red dwarf star approximately 10.30 light-years (3.16 parsecs) from Earth in the northern constellation of Andromeda. Despite its proximity it is too dim to be seen with the naked eye.

Key takeaways

Ross 248 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ross 248 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ross 248 from memory before moving on to harder problems.

Reference excerpt

Ross 248, also called HH Andromedae or Gliese 905, is a red dwarf star approximately 10.30 light-years (3.16 parsecs) from Earth in the northern constellation of Andromeda. Despite its proximity it is too dim to be seen with the naked eye. It was first catalogued by Frank Elmore Ross in 1926 with his second list of proper-motion stars. It was too dim to be included in the Hipparcos survey. In about 40,000 years, Voyager 2 will pass within 1.7 ly (0.52 pc) of Ross 248. Within the next 80,000 years, Ross 248 is predicted to be the nearest star to the Sun for around 9,000 years, overtaking the current nearest star, the triple system Alpha Centauri.

Characteristics

This star has about 14% of the Sun's mass and 19% of the Sun's radius, but only 0.2% of the Sun's luminosity. It has a stellar classification of M6 V, which indicates it is a type of main-sequence star known as a red dwarf. This is a chromospherically-active star. With high probability, there appears to be a long-term cycle of variability with a period of 4.2 years. This variability causes the star to range in visual magnitude from 12.23 to 12.34. In 1950, this became the first star to have a small variation in magnitude attributed to spots on its photosphere as it rotates, a class known as BY Draconis variables. Examining the proper motion of Ross 248 has found no evidence of a brown dwarf or stellar companion orbiting between 100–1,400 AU, and other unsuccessful searches have been attempted using both the Hubble Space Telescope Wide Field Planetary Camera and by near-infrared speckle interferometry. Long-term observations by the Sproul Observatory show no astrometric perturbations by any unseen companion.

Distance from the Sun

The space velocity components of this star in the galactic coordinate system are [U, V, W] = [−32.9±0.7, −74.3±1.3, 0.0±1.4] km/s. The trajectory of Ross 248 will bring it closer to the Solar System. In 1993, Matthews projected that in about 33,000 years it would enter a period of about 9,000 years as the closest star to the Sun, as close as 3.024 light-years (0.927 parsecs) in 36,000 years. A more precise estimate in 2022 has it approaching to within 3.048 ly (0.9345 pc) in 36,500 years. Any future spacecraft that escaped the Solar System with a velocity of 25.4 km/s would reach this star 37,000 years from now, when the star just passes its nearest approach. By comparison, the Voyager 1 has an escape velocity of 16.6 km/s. Voyager 2 is not headed toward any particular star, although in roughly 42,000 years, it will pass the star Ross 248 at a distance of 1.7 light-years. The closest stellar neighbors to Ross 248 are the binary systems Groombridge 34, at 1.8 light-years away, and Kruger 60, at 4.5 light-years.

See also List of nearest stars Lists of stars

References

Sources Riaz, Basmah; Gizis, John E.; Harvin, James (2006). "Identification of New M Dwarfs in the Solar Neighborhood". The Astronomical Journal. 132 (2): 866–872. arXiv:astro-ph/0606617. Bibcode:2006AJ....132..866R. doi:10.1086/505632. S2CID 6282011. Table 1. Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Berta-Thompson, Zachory K. (2014). "Trigonometric Parallaxes for 1507 Nearby Mid-to-late M Dwarfs". The Astrophysical Journal. 784 (2): 156. arXiv:1312.3241. Bibcode:2014ApJ...784..156D. doi:10.1088/0004-637X/784/2/156. S2CID 18789867. Table with parallaxes.

External links "Ross 248". Sol Station. Archived from the original on April 26, 2001. SolStation.com: Ross 248 Image HH Andromedae

Illustrations

Worked examples

Example 1 — a first encounter with Ross 248

Start with the simplest possible case. Write down what Ross 248 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 Ross 248 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 Ross 248 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 Ross 248

In research: Ross 248 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 Ross 248 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: Ross 248 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Andromeda (constellation), BY Draconis variables, Gliese and GJ objects, so understanding it makes those chapters shorter.
In everyday life: Look for Ross 248 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 Ross 248 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ross 248 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 Ross 248 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ross 248 in simple terms?

Why does Ross 248 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 Ross 248?

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 Ross 248.