astronomy

V1298 Tauri

V1298 Tauri 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 V1298 Tauri rather than just read about it. In short: V1298 Tauri is a young (23±4 Myr) weakly-lined T Tauri star that is part of the Taurus-Auriga association in the Taurus Molecular Cloud. Alternatively it is part of a proposed moving group, called Group 29 (or 93 Tau group) that is slightly older.

Key takeaways

V1298 Tauri belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect V1298 Tauri to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of V1298 Tauri from memory before moving on to harder problems.

Reference excerpt

V1298 Tauri is a young (23±4 Myr) weakly-lined T Tauri star that is part of the Taurus-Auriga association in the Taurus Molecular Cloud. Alternatively it is part of a proposed moving group, called Group 29 (or 93 Tau group) that is slightly older. The system has four transiting exoplanets, discovered with the Kepler space telescope in the K2 mission. One of the planets was discovered in August 2019 and the other three were discovered in November 2019 by the same team.

Stellar characteristics

V1298 Tauri has a spectral type of K0 - K1.5 and it has a mass of about 1.1 M☉. The star appears in x-rays from ROSAT data and it does show strong lithium absorption lines, both signatures of youth and therefore it was a proposed member of Taurus-Auriga. On the other hand it does not show signs of accretion and it lacks infrared excess. Instead it shows H-alpha in absorption. In 2007, Konstantin Nikolaevich Grankin et al. announced their discovery that V1298 Tauri is a variable star. It was given its variable star designation in 2011. The brightness of V1298 Tauri varies in an unpredictable way between a maximum visual magnitude of 10.31 and a minimum of 10.54. The light curve of the star shows quasi-periodic variability that was interpreted as stellar rotation and starspots. The light curve also showed several flares. Based on Gaia DR2 data this star is part of a co-moving pair, together with HD 284154. The star is included in an analysis of the 93 Tau group, which finds an age of 35±5 Myr.

Planetary system The planets around V1298 Tauri are super-puffs with some of the lowest densities ever recorded, which is attributed to their young age. Over time the planets will shrink and become super-Earths and sub-Neptunes. Additionally planet c is suspected to have a ‘boil-off’ phase when the disk around the star disperses. V1298 Tauri has four confirmed planets of which planets c, d and b are near a 2:3:6:12 resonance (with periods of 8.25, 12.40 24.14, and 48.68 days). The system is very young and might be a precursor of a compact multiplanet system. The 2:3 resonance suggests that some close-in planets may either form in resonances or evolve into them on timescales of less than 10 Myr. The planets c, d in the system have a size between Neptune and Saturn. Planets b, e have sizes similar to Jupiter. Planet e was recovered and detected with K2, LCO, TESS and possibly CHEOPS. It has an orbital period of 48.7 days and it has a 2:1 commensurability with planet b, which shows large TTVs due to the interaction. Orbits of the planets b and c are nearly coplanar and planet c is not inclined to the equatorial plane of the star, misalignment equals to 2+12−4 degrees. Models predict that the planets have a minimum core mass of 5 M🜨 and are surrounded by a thick envelope that make up 20% of their mass. The total mass of planet c and d was predicted to be 2 - 28 M🜨 and the total mass of planet d and b was predicted to be 9 - 120 M🜨. In a follow-up paper the mass of V1298 Tauri b was constrained to <2.2 MJ. The masses were measured with transit timing variations (TTVs) and are in the range of super-Earths to sub-Neptunes. The planet c was suspected to be shedding mass due to intense irradiation by the host star, but hydrogen tail existence was refuted by 2021. Additionally planet c has a non-detection of helium, which provided limits for mass-loss rates. A Hubble WFC3 transmission spectrum was obtained for planet c and hazes could not be ruled out for planet c. Planet e could be a planet with a water-rich core and a substantial hydrogen envelope. Carbon disulfide is detected in planet e's atmosphere by JWST spectroscopy, consistent with a model with low metallicity, carbon-to-oxygen ratio higher than the Sun, and a relatively cool internal temperature of 303 ± 72 K. This constrasts it with neighbouring planet b, which shows sulfur dioxide instead but has otherwise similar characteristics.

Planet b Planet b was observed with Hubble WFC3 and a transmission spectrum was produced. This observation found a clear primordial atmosphere and water vapor absorption. The mass was constrained from this observation to less than 23 earth-masses, making this planet one of the lowest density planet observed. The team retrieved a low metallicity for the atmosphere, challenging formation mechanisms. The planet will likely evolve into a sub-Neptune in the future. An additional study found that planet b has a large, haze-free envelope. A research team studied planet b with JWST NIRSpec and Hubble WFC3 transmission spectroscopy. The team found a haze-free, H/He-dominated atmosphere with a large scale height of around 1500 km. The team detected carbon dioxide, water vapor, methane, sulfur dioxide and carbonyl sulfide in the atmosphere of the planet. The mass was inferred to be 12 ± 1 M🜨 (free retrieval) and 15 ± 1.7 M🜨 (grid modelling) using the scale height. The metallicity was found to be low compared to a mature sub-Neptune. Especially methane was found to be lower than equilibrium chemistry. The model requires the planet to have a hot internal temperature of 500 K (227 °C; 440 °F) and vertical mixing, which helps to explain the low methane. This hot internal temperature is higher than expected. The planet might have a deep atmospheric metallicity gradient and mass loss from the atmosphere might enhance the metallicity over time.

See also List of nearby stellar associations and moving groups List of exoplanets discovered in 2019 Kepler-223 - the first confirmed system with four exoplanets in resonance K2-138 - a system with five exoplanets in a 3:2 resonance chain HD 110067 - a system with seven planets in orbital resonance Kepler-51 - another young system with at least three super-puff planets

References

Illustrations

Worked examples

Example 1 — a first encounter with V1298 Tauri

Start with the simplest possible case. Write down what V1298 Tauri 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 V1298 Tauri 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 V1298 Tauri 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 V1298 Tauri

In research: V1298 Tauri 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 V1298 Tauri 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: V1298 Tauri is common in secondary-school and first-year university syllabi. It links to neighbouring topics K-type pre-main-sequence stars, Objects with variable star designations, Planetary systems with four confirmed planets, so understanding it makes those chapters shorter.
In everyday life: Look for V1298 Tauri 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 V1298 Tauri in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what V1298 Tauri 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 V1298 Tauri out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is V1298 Tauri in simple terms?

Why does V1298 Tauri 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 V1298 Tauri?

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 V1298 Tauri.