WASP-103b

Key takeaways

WASP-103b belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WASP-103b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WASP-103b from memory before moving on to harder problems.

Reference excerpt

WASP-103b is an ultra-hot Jupiter orbiting around WASP-103, a late F8V-type main sequence star located in the Constellation of Hercules. It orbits at a distance of 0.019 AU with an eccentricity of 0.15. It significantly larger than Jupiter being roughly 1.5 times its mass and 1.6 times its radius. The planet has an oval shape similar to that of a rugby ball. This is due to the force of gravity exerted by its parent star. It is the first exoplanet to have a deformation detected.

Discovery WASP-103b was discovered by Gillon et al. (2014) in the year 2014 via the transit method. The star WASP-103 was observed by the southern station of the WASP (Wide Angle Search for Planets) survey during three observing seasons conducted in 2010 from May 15 to August 16, 2011 from March 26 to August 20 and 2012 from March 25 to June 28. The star was considered a high-priority candidate target due to the presence of a transit-like signal that occurred every ~0.926 days. Follow-up observations would then be done on the star with the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST). These follow-up observations observed three transits.

Orbit WASP-103b is a ultrashort period (USP) planet that orbits at a distance of 0.01986 astronomical units (AU) taking only 22.2 hours to complete an orbit around its parent star. It has an orbital eccentricity of 0.15.

Orbital decay WASP-103b is a strong candidate to be effected by tidally-induced orbital decay. Birkby et al. (2014) calculated that orbital decay, if present in several close-in planets including WASP-103b, would cause a shift in the transit time of the planet over a period of around a decade. The detection of such shifts in transit time would require precise observations of WASP-103b occurring over many years along with ephemeris against which to measure deviations from strict periodicity. A study carried out by Patra et al. (2020) aimed to detect evidence for orbital decay in several hot Jupiters including WASP-103b. However none of the planets observed in the study, except for WASP-12b and possibly WASP-19b, showed convincing evidence of orbital decay. However further observations of these planets have been encouraged. Despite orbiting very close to its parent star, it seems that WASP-103b is moving away from it, instead of getting closer. This gives rise to the theory that it is a binary system, or that the orbit of the exoplanet in question is elliptical.

Characteristics WASP-103b is significantly more massive than Jupiter being 1.49 times more massive with a radius of about 1.603 ±0.052 Jupiter radii. It experiences extreme irradiation from its parent star at ~9x109 ergs s-1 cm-2. The temperature of WASP-103b ranges from day to night with the dayside being significantly hotter than the night. It has a temperature of 2930 ±40 Kelvin and an nightside temperature of 1880 ±40 K. This would make this planet around twenty times hotter than Jupiter. This data would suggest that WASP-103b has an interior structure similar to Jupiter. The Southern African Large Telescope (SALT) had observed marginal evidence for increased chromospheric activity on its parent star. If this turns out to be the case, this may suggest interactions between the star and planet.

Gravitational deformation

The gravitational pull from its host star leads to WASP-103b being tidally deformed into a shape that is similar to a Rugby ball. This is because WASP-103b has a Roche lobe filling factor of 0.58 which leads to the planet significantly deviating from its spherical shape. It is also possible that WASP-103b experiences mass loss due to Roche-lobe overflow. Either way, WASP-103b experiences extreme tidal deformation and is on the edge of tidal disruption which places it in a similar subgroup of ultrashort period gas giant exoplanets as OGLE-TR-56b.

Atmospheric composition The planet is moderately metal-enriched being 100x times more enriched than its host star which has near-solar values. WASP-103b has large abundances of Iron(I) hydride (FeH), hydrides, Carbon dioxide, and Methane. Observations of WASP-103b taken in 2018 from the Spitzer and Hubble Space Telescopes (HST) seemed to lack spectral features of water that is often attributed to partial water dissociation. If WASP-103b did it have water, it would have been in contrast to cooler hot Jupiters. However further observations from ground telescopes such as the Very Large Telescope (VLT) detected water in its atmosphere at low abundances. Those same observations were not able to rule out the presence of Sodium (Na). It also has a carbon-to-oxygen ratio that is below 0.9.

See also Examples of tidally stretched exoplanets with measured shapes include:

WASP-12b, a hot Jupiter WASP-121b (named Tylos), another hot Jupiter PSR J2322−2650 b, a pulsar planet

References

Illustrations

Worked examples

Example 1 — a first encounter with WASP-103b

Start with the simplest possible case. Write down what WASP-103b 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 WASP-103b 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 WASP-103b 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 WASP-103b

In research: WASP-103b 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 WASP-103b 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: WASP-103b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by WASP, Exoplanets discovered in 2014, Hercules (constellation), so understanding it makes those chapters shorter.
In everyday life: Look for WASP-103b 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.

How to study WASP-103b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WASP-103b 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 WASP-103b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WASP-103b in simple terms?

WASP-103b is an ultra-hot Jupiter orbiting around WASP-103, a late F8V-type main sequence star located in the Constellation of Hercules. It orbits at a distance of 0.019 AU with an eccentricity of 0.15.

Why does WASP-103b 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 WASP-103b?

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 WASP-103b.