astronomy

OGLE-2005-BLG-390L

OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L rather than just read about it. In short: OGLE-2005-BLG-390L is a star thought to be a spectral type M (a red dwarf; 95% probability, 4% probability it is a white dwarf, <1% probability it is a neutron star or black hole). This galactic bulge star is located in the Scorpius constellation at a far distance of about 21,500 light years, near the border with Sagittarius.

Key takeaways

OGLE-2005-BLG-390L belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OGLE-2005-BLG-390L to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OGLE-2005-BLG-390L from memory before moving on to harder problems.

Reference excerpt

OGLE-2005-BLG-390L is a star thought to be a spectral type M (a red dwarf; 95% probability, 4% probability it is a white dwarf, <1% probability it is a neutron star or black hole). This galactic bulge star is located in the Scorpius constellation at a far distance of about 21,500 light years, near the border with Sagittarius.

Planetary system

OGLE-2005-BLG-390L has one known planet, which was discovered using the technique of gravitational microlensing. Indications are that the planet is about five times Earth mass, orbiting at about 2.6 astronomical units from the parent star. The discovery was announced on January 25, 2006. OGLE-2005-BLG-390Lb was once considered one of the smallest known extrasolar planets around a main sequence star, possibly rocky, with a mass around 5.5 times that of the Earth. The orbital radius (assuming a circular orbit) of the planet is 2.6 AU, however the orbital elements are unknown. Based on its low mass and estimated temperature of around 50 K, the planet is thought to consist mainly of ices, like Pluto or Uranus, rather than being a Jupiter-like gas giant.

See also List of stars with extrasolar planets OGLE-2005-BLG-169L Optical Gravitational Lensing Experiment (OGLE)

References

External links OGLE: 2005-BLG-390 Event Small Rocky Planet Found Orbiting Normal Star OGLE-2005-BLG-390L b

Illustrations

Worked examples

Example 1 — a first encounter with OGLE-2005-BLG-390L

Start with the simplest possible case. Write down what OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L

In research: OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L 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: OGLE-2005-BLG-390L is common in secondary-school and first-year university syllabi. It links to neighbouring topics Gravitational lensing, M-type main-sequence stars, Planetary systems with one confirmed planet, so understanding it makes those chapters shorter.
In everyday life: Look for OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OGLE-2005-BLG-390L in simple terms?

Why does OGLE-2005-BLG-390L 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 OGLE-2005-BLG-390L?

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 OGLE-2005-BLG-390L.