GEORGE SEABROKE

Mapping the Milky Way from space

MULLARD SPACE SCIENCE LABORATORY

Credits: ESA/ATG medialab;

background image: ESO/S. Brunier

MULLARD SPACE SCIENCE LABORATORY

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Milky Way (artist’s impression):How many stars?

Credit: NASA/JPL-Caltech/R. Hurt

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Milky Way (artist’s impression):100-200 billion stars

Credit: NASA/JPL-Caltech/R. Hurt

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Gaia will measure astrometry & photometry of ? stars & radial velocities of ? stars

Credit: NASA/JPL-Caltech/R. Hurt

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Gaia will measure astrometry & photometry of 1 billion stars & radial velocities of 75-100 million stars

Credit: NASA/JPL-Caltech/R. Hurt

Distribution of stars for

which radial velocities

will be precisely

(< 15 km/s) measured

(V < 15.2)

in a mock spiral galaxy

as seen by Gaia, as

predicted by

SNAPDRAGONS

(Hunt et al. 2015)

Log (star #)

MULLARD SPACE SCIENCE LABORATORY

Credit: Leanne Guy

One of the primary mirrors being mounted on Gaia

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Credit: Astrium SAS

Gaia’s 106 CCDs integrated onto its focal plane

Gaia’s 106 CCDs integrated onto its focal plane

Credit: Astrium

106 digital cameras, each with 8.8 Mega pixels 106 x 8,847,000 pixels = 937,782,000 pixels Nearly 1 billion pixels or 1000 Mega pixels!

0.5°

Gaia0.000000002°

0.000000002°

Spectroscopy

Redder colours:

longer wavelengths

Bluer colours:

shorter wavelengths

Electromagnetic spectrumVictor Blacus (http://en.wikipedia.org/wiki/File:Electromagnetic-Spectrum.svg)

Victor Blacus (http://en.wikipedia.org/wiki/File:Electromagnetic-Spectrum.svg)

Electromagnetic spectrum

Doppler effect with sound waves

Doppler effect with sound waves

Doppler effect with light waves

http://www.astronomynotes.com/light/s10.htm

What is a radial velocity?

What is a radial velocity?

Position

DDistance measured by parallax

What is a radial velocity?

Position

DDistance measured by parallax

What is a radial velocity?

Position

DDistance measured by parallax

Distanceconverts

proper motionsto

transverse velocity (Vt)

What is a radial velocity?

Position

Effect of parallax (the Earth’s orbital motion around the Sun, with a period of 1 year).

System’s barycentricmotion viewed from the Solar System barycentre.

Exo-Planets

System’s barycentricmotion viewed from the Solar System barycentre.

Effect of parallax (the Earth’s orbital motion around the Sun, with a period of 1 year).

Apparent motion of the star as a result of the planet, theadditional perturbation being magnified by ×30 for visibility.

DDistance measured by parallax

Distanceconverts

proper motionsto

transverse velocity (Vt)

Space velocity (any direction)

What is a radial velocity?

Position

DDistance measured by parallax

Distanceconverts

proper motionsto

transverse velocity (Vt)

Space velocity (any direction)

Radial velocity (Vr)

What is a radial velocity?

Position

http://www.projectrho.com/public_html/starmaps/media/4dmaps/spacevel.png

Modelling the Milky Way using supercomputersRob Grand, Jason Hunt (PhD students), Daisuke Kawata, MSSL

http://en.wikipedia.org/wiki/Oort_cloud

Gaia’s first science result: supernova!

Gaia’s first science result: supernova!

• hosts more than 10 billion photos

• hosts more than 10 billion photos• 1 petabytes (PB) = 1 million gigabytes (GB)

• hosts more than 10 billion photos• 1 petabytes (PB) = 1 million gigabytes (GB)

• Gaia’s final processed data storage = several PB

Summary

• Great recent years for the European Space Agency!

• 3 take home messages about Gaia:–Amazing (European) technology–Stars move!–You can get involved!