T elescopes T elescopes Ryan Orvedahl Ryan Orvedahl ASTR 1040 - - PowerPoint PPT Presentation

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Nov 15, 2023 142 likes •345 views

T elescopes T elescopes Ryan Orvedahl Ryan Orvedahl ASTR 1040 Rec ASTR 1040 Rec T odays Class - T odays Class - T elescopes T elescopes Measuring a telescopes Measuring a telescopes performance performance Ways to

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T elescopes T elescopes

Ryan Orvedahl Ryan Orvedahl ASTR 1040 Rec ASTR 1040 Rec

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T

day’s Class -

T

day’s Class -

T elescopes T elescopes

Measuring a telescope’s Measuring a telescope’s performance performance Ways to measure light Ways to measure light Angular resolution Angular resolution Aperture synthesis Aperture synthesis

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T elescope Fundamentals T elescope Fundamentals

Light is a wave Light is a wave Light is a particle Light is a particle

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T elescope Fundamentals T elescope Fundamentals

Measures of telescope performance: Measures of telescope performance:

Ability to collect and measure light (efgective Ability to collect and measure light (efgective area) area) How big does a point look? (angular How big does a point look? (angular resolution) resolution) Ability to separate wavelengths (spectral Ability to separate wavelengths (spectral resolution) resolution)

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Collecting & Measuring Collecting & Measuring Light Light

Measurin g Waves Measuring Particles

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Angular Resolution Angular Resolution

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Angular Resolution Angular Resolution

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Angular Resolution Angular Resolution

Difgraction Difgraction

For a circular aperture: For a circular aperture:

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Angular Resolution Angular Resolution

What is What is D D? ?

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Angular Resolution Angular Resolution

Suppose you wanted to take an image (2 Suppose you wanted to take an image (2 pixels by 2 pixels) of Alpha Centauri A, one of pixels by 2 pixels) of Alpha Centauri A, one of

ur nearest stellar neighbors at 4.3 ly away.
ur nearest stellar neighbors at 4.3 ly away.

Assume that it has a radius of 1.2 R Assume that it has a radius of 1.2 Rsun

sun and

and you want a picture in optical light ( you want a picture in optical light (l l = 500 = 500 nm). How big of a difgraction limited nm). How big of a difgraction limited telescope would you need? telescope would you need?

Constants and Constants and Conversions Conversions R Rsun

sun = 700 Mm

= 700 Mm 1 ly = 9.5 x 10 1 ly = 9.5 x 1015

15 m

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Angular Resolution Angular Resolution

Clicker Question: Now suppose you want both Clicker Question: Now suppose you want both an optical ( an optical (l l = 500 nm) image of alpha = 500 nm) image of alpha Centauri and a radio ( Centauri and a radio (l l = 5 mm) image with = 5 mm) image with the same angular resolution. What how big of the same angular resolution. What how big of a difgraction limited radio telescope would you a difgraction limited radio telescope would you need? need?

A. 2.89 mm C. 2.89 km
A. 2.89 mm C. 2.89 km
B. 2.89 m D. 289 km
B. 2.89 m D. 289 km

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Angular Resolution Angular Resolution

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Aperture Synthesis Aperture Synthesis

Interferometers Interferometers

Combine signals from Combine signals from difgerent telescopes difgerent telescopes Get the difgraction limit Get the difgraction limit

f a telescope as big as
f a telescope as big as

the distance between the distance between the telescopes the telescopes Requires very careful Requires very careful

ptics or atomic clocks
ptics or atomic clocks

and fast computers and fast computers

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Aperture Synthesis Aperture Synthesis

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Aperture Synthesis Aperture Synthesis

Atacama Large Millimeter Array (ALMA)

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Aperture Synthesis Aperture Synthesis

6 telescopes 6 telescopes

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Aperture Synthesis Aperture Synthesis

25 telescopes 25 telescopes

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Aperture Synthesis Aperture Synthesis

640 telescopes 640 telescopes

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