astronomy

WISE 1541−2250

WISE 1541−2250 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 WISE 1541−2250 rather than just read about it. In short: WISE 1541−2250 (full designation WISEPA J154151.66−225025.2) is a brown dwarf of spectral class Y0.5, located in the constellation Libra at approximately 18.6 light-years from Earth. This object received popular attention when its discovery was announced in 2011 at a distance estimated to be only about 9 light-years, which would have made it the closest brown dwarf known.

Key takeaways

WISE 1541−2250 belongs to astronomy; place it in that map before memorising details.
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Connect WISE 1541−2250 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WISE 1541−2250 from memory before moving on to harder problems.

Reference excerpt

WISE 1541−2250 (full designation WISEPA J154151.66−225025.2) is a brown dwarf of spectral class Y0.5, located in the constellation Libra at approximately 18.6 light-years from Earth. This object received popular attention when its discovery was announced in 2011 at a distance estimated to be only about 9 light-years, which would have made it the closest brown dwarf known. (For really close brown dwarfs see, for example, Luhman 16, WISE 1506+7027, Epsilon Indi Ba, Bb, or UGPS 0722-05). It is not the farthest known Y-type brown dwarf to Earth.

History of observations

Discovery WISE 1541−2250 was discovered in 2011 from data collected by the Wide-field Infrared Survey Explorer (WISE) in the infrared at a wavelength of 40 cm (16 in), whose mission lasted from December 2009 to February 2011. WISE 1541−2250 has two discovery papers: Kirkpatrick et al. (2011) and Cushing et al. (2011) with mostly the same authors and published nearly simultaneously.

Kirkpatrick and collaborators presented the discovery of 98 brown dwarf systems with components of spectral types M, L, T and Y, among which was WISE 1541−2250. Cushing and collaborators presented the discovery of seven brown dwarfs, one of the T9.5 type and six of the Y-type, the first members of the Y spectral class discovered and spectroscopically confirmed, including an "archetypal member" of the Y spectral class, WISE 1828+2650, and WISE 1541−2250. These seven objects are also the faintest seven of 98 brown dwarfs presented in Kirkpatrick et al. (2011).

Distance Currently the most accurate distance estimate of WISE 1541−2250 is a trigonometric parallax, published in 2014 by Tinney et al.: 0.1751 ± 0.0044 arcsec, corresponding to a distance 5.71+0.15−0.14 pc, or 18.6 ± 0.5 ly. For several months after its discovery, before the publication of its parallax by Kirkpatrick et al. in 2012, WISE 1541−2250 was considered to be the nearest known brown dwarf at approximately 9 light-years from the Sun, and the seventh-nearest of all star systems, at slightly more than twice the distance of the nearest known star system Alpha Centauri. This view existed because of a very rough preliminary parallax with a baseline of 1.2 years, published in the discovery paper: 0.351 ± 0.108 arcsec, corresponding to a distance 2.8+1.3−0.6 pc, or 9.3+4.1−2.2 ly. Also, there were other estimates: spectrophotometric distance estimate 8.2 pc (26.7 ly), and photometric distance estimate 1.8+0.2−0 pc (5.9+0.6−0 ly).

Space motion WISE 1541−2250 has proper motion of about 899 milliarcseconds per year.

Physical properties WISE 1541−2250 is among the first known examples of a Y-class brown dwarf, the coldest spectral class of stars, and has temperature about 381 K (108 °C; 226 °F). Its spectral class is Y0.5 (initially was estimated as Y0). Modelling of WISE 1541−2250 has shown that there could be water clouds in the atmosphere of this brown dwarf. Models however struggle to reproduce the spectrum even with water clouds. A study using JWST NIRSpec and MIRI data found an elevated abundance of carbon monoxide and carbon dioxide. Additionally the model favours gray cloud cover. The model suggest the cloud top is located at 0.47+0.04−0.06 bar, which is close the condensation temperature of water vapor, but is too warm for condensation. The optical depth supports an optical dense and vertical extended cloud layer, consistent with the onset of water cloud formation. Stable cloud layers predicted by the FastChem code are arsenic(II) sulfide (As2S2) and ammonium bromide near 0.5 bar. It is unclear if these compounds could form optically thick clouds. Neither water nor sodium sulfide clouds are predicted to be present by FastChem.

See also The other six discoveries of brown dwarfs, published in Cushing et al. (2011):

WISE 0148−7202 (T9.5) WISE 0410+1502 (Y0) WISE 1405+5534 (Y0 (pec?)) WISE 1738+2732 (Y0) WISE 1828+2650 (≥Y2) WISE 2056+1459 (Y0) Lists:

List of brown dwarfs List of nearest stars List of Y-dwarfs

Notes

References

Marsh, Kenneth A.; Wright, Edward L.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Cushing, Michael C.; Griffith, Roger L.; Skrutskie, Michael F.; Eisenhardt, Peter R. (2013). "Parallaxes and Proper Motions of Ultracool Brown Dwarfs of Spectral Types Y and Late T". The Astrophysical Journal. 762 (2): 119. arXiv:1211.6977. Bibcode:2013ApJ...762..119M. doi:10.1088/0004-637X/762/2/119. S2CID 42923100. Beichman, Charles A.; Gelino, Christopher R.; Kirkpatrick, J. Davy; Cushing, Michael C.; Dodson-Robinson, Sally; Marley, Mark S.; Morley, Caroline V.; Wright, Edward L. (2014). "WISE Y Dwarfs As Probes of the Brown Dwarf-Exoplanet Connection". The Astrophysical Journal. 783 (2): 68. arXiv:1401.1194. Bibcode:2014ApJ...783...68B. doi:10.1088/0004-637X/783/2/68. S2CID 119302072.

External links Choi, Charles Q. (August 26, 2011). "Y dwarf star? Because they're cool, that's Y!". Space.com. Retrieved August 31, 2011. NASA news release Archived 2016-01-10 at the Wayback Machine Science news Archived 2011-10-07 at the Wayback Machine Solstation.com (New Objects within 20 light-years)

Illustrations

Worked examples

Example 1 — a first encounter with WISE 1541−2250

Start with the simplest possible case. Write down what WISE 1541−2250 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 WISE 1541−2250 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 WISE 1541−2250 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 WISE 1541−2250

In research: WISE 1541−2250 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 WISE 1541−2250 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: WISE 1541−2250 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2011, Brown dwarfs, Libra (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for WISE 1541−2250 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 WISE 1541−2250 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WISE 1541−2250 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.
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Frequently asked questions

What is WISE 1541−2250 in simple terms?

Why does WISE 1541−2250 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 WISE 1541−2250?

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 WISE 1541−2250.