6dFGS Workshop, Epping 11 July 2003 Fred Watson (and the RAVErs)
This page is intentionally blank. A new view of the Universe VIII Fred Watson (and the RAVErs) April...
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Transcript of This page is intentionally blank. A new view of the Universe VIII Fred Watson (and the RAVErs) April...
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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...