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A new view of the Universe VIII

Fred Watson (and the RAVErs)

April 2005

A new view of the Universe VIII

Fred Watson (and the RAVErs)

April 2005

More geography of the Milky

Way Galaxy More geography of the Milky

Way Galaxy

Galaxies…

NGC 2997 – a near-twin of the Milky Way

If this was our Galaxy,we’d be here

Edge-on view of a spiral galaxy:Disc

BulgeThick disc

The Galaxy’s halo of dark

matter, old stars and globular clusters

And lurking at the centre of our Galaxy…

What is RAVE? What is RAVE? (And why are we RAVEing?) (And why are we RAVEing?)

What is RAVE? RAdial Velocity ExperimentInternational collaboration—22 scientists in 11 nationsPI: Matthias Steinmetz, AIPAll-sky survey of stellar radial velocities & agesUltimate aim: 50 million stars, complete to I=15Enables true galactic archaeologySpawned from (now-defunct) space missionsUK Schmidt Telescope and a northern counterpartCompletely externally funded ($A, £, €, $US, ¥?)Public data-base; VO compliant

Science goals Comparison with simulations of structure-growthwithin a CDM Universe (Steinmetz & Navarro, 2002)Substructure in the halo (cold stellar streams)Chemical signatures ([/Fe], [Fe/H]) to identifycommon formation sites among widely-separated starsFormation of bulgesOrigin of the thick diskDynamical state of the thin disk and neighbouring spiral arms

Science goals...

www.aip.de/RAVE/

The galactic halo is thought

to be made up of swarms of stars.

We can detect them by plotting their positions in

phase space.

They come from satellite galaxies

gobbled up in the past by the

Milky Way.

More galactic archaeology:

Results from the Geneva-

Copenhagen survey of

14,000 Sun-like stars in the local neighbourhood.

And this is just the start…

Multi-object spectroscopy with fibre optics

The answer to life, the Universe and everything...

Detector

Spectrograph

Slit

More RAVEing

Phase I: April 2003–June 2005, using unallocated UKST bright-of-moon time during the 6dF Galaxy Survey, funded by AAO and RAVE.About 100,000 stars with 9<I<12.Observe in the far red region of the spectrum.Currently measuring 700 stars per clear night.Phase II: 2006–10, all UKST time once the Galaxy Survey is complete.Goal is to measure 30,000,000 stars with I<15. But… need to measure 22,000 stars per night.

Instruments for RAVEing Instruments for RAVEing

Phase I instrumentation: 6dF robot

Cute, isn’t it?

Yours might becute—but mine’s

bigger…

6dF on the UK Schmidt Telescope

•6-deg field-of-view pick-place fibre system•Off-telescope robot•Two field plate units •150×7” science fibres •Fixed spectrograph•Turn-round ~20 min•Reconfig. time ~60m•Up to 8 fields/night•Commissioned 2001•OzPoz prototype S/g

6dF

6dF field-plate unit

40 cm

Back of field-plate unit

6dF fibre buttons parked on field plate

Robot at work:

6dF is too slow for 22,000 stars per night...

Therefore adapt the 400-fibre positioner currently being developed by AAO for Subaru

Echidna Ball-Spine Array

Phase II instrumentation

Spine A (1 of 3 made)

Spine B (3 of 3 made)

Prototype spines

– 2250 spines (each with 15 arcmin patrol area)– Covers full field area of 6 6 deg2

– 1 minute reconfiguration time– Feeds spectrograph with 3750 banks of spectra– AAO estimates positioner will cost ~ € 2.4M– AIP builds the spectrograph @ ~ € 0.8M ?– How might it be funded...?

Echidna for RAVE

UKST can only access the southern 2/3 of the sky.

Therefore RAVE needs a northern-hemisphere counterpart.

Favoured candidate is the 0.8-m Schmidt at Calar Alto, Spain.

It would need its own Ukidna and spectrograph.

What about the north?

Calar Alto Schmidt

RAVE’s ProgressRAVE’s Progress

First data-release: July 2005 on Edinburgh data-server.

$A vs. €

$A vs. £

$A vs. $US

$A vs. ¥

RAVE spectrum?

RAVE’s future RAVE’s future

The Way Forward…

On 30.6.2005 the AAT Board ceases to support UKST operations

Ukidna cannot be ready before 2007…if ever

Current proposal is to extend Phase I for >2 years.

RAVE uses all UKST time (up to 25 nights per month).

Annual cost to RAVE ~ €250k + visiting observers.

Collect >400,000 spectra—buying time for Phase II...

OR—provide a useful sample with which to end the survey

But the hope and intention is to RAVE on...