VLT-SPHERE | TriviaQuestions.online

⭐ In the context of variable stars, a change in apparent magnitude caused by a star being periodically obscured by a companion star would classify it as what type of variable?

Extrinsic variables are defined by changes in brightness caused by external factors affecting the amount of light reaching Earth, like an orbiting companion eclipsing the star, rather than changes in the star's own luminosity.

⭐ Core Definition: VLT-SPHERE

Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). It provides direct imaging as well as spectroscopic and polarimetric characterization of exoplanet systems. The instrument operates in the visible and near infrared, achieving exquisite image quality and contrast over a small field of view around bright targets.

Results from SPHERE complement those from other planet finder projects, which include HARPS, CoRoT, and the Kepler Mission. The instrument was installed on Unit Telescope "Melipal" (UT3) and achieved first light in May, 2014. At the time of installation, it was the latest of a series of second generation VLT-instruments such as X-shooter, KMOS and MUSE.

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👉 VLT-SPHERE in the context of Variable star

A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either:

Intrinsic variables, whose inherent luminosity changes; for example, because the star swells and shrinks.
Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it.

Depending on the type of star system, this variation can include cyclical, irregular, fluctuating, or transient behavior. Changes can occur on time scales that range from under an hour to multiple years. Many, possibly most, stars exhibit at least some oscillation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle. At the opposite extreme, a supernova event can briefly outshine an entire galaxy. Of the 58,200 variable stars that have been catalogued as of 2023, the most common type are pulsating variables with just under 30,000, followed by eclipsing variables with over 10,000.

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