The Galactic Plane in H The Galactic Plane in H and at 1 and at 1 arcsec resolution: arcsec resolution: (The north as seen by IPHAS) (The north as seen by IPHAS) Janet Drew, Imperial College London Janet Drew, Imperial College London STScI, 11 STScI, 11 th th July July 2007 2007 (image: N. Wright (image: N. Wright UCL) UCL)
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The Galactic Plane in H and at 1 arcsec resolution: (The north as seen by IPHAS) Janet Drew, Imperial College London STScI, 11 th July 2007 (image:
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The Galactic Plane in HThe Galactic Plane in Hand at 1 arcsec and at 1 arcsec resolution: resolution:
(The north as seen by IPHAS)(The north as seen by IPHAS)
Janet Drew, Imperial College LondonJanet Drew, Imperial College London
STScI, 11STScI, 11thth July 2007 July 2007
(image: N. Wright UCL)(image: N. Wright UCL)
Talk Outline
• Introduction/motivation
• IPHAS – the survey
• IPHAS science
• Conclusion
(i)(i) NebulaeNebulae
(ii)(ii) Emission line starsEmission line stars
(iii)(iii) Stellar populations from the photometryStellar populations from the photometry
1. To rectify scarcity of stellar objects in short-lived early and late phases of stellar evolution
H emission common among young/old/luminous/compact stellar objects
2. In the north, better coverage of PNe for studying galactochemical gradient outside the Solar Circle
access to compact and faint nebulae
Reasons to survey the Galactic Plane in Hat 1 arcsec resolution
Reasons (continued)
3. To trace the structure of the Galactic disk
H = star-formation indicator
emission line stars as spiral arm tracers
4. General stellar population photometry:
H narrow-band measurement, linked with
broad-band data yields…
spectral type sensitivity, giving photometric discrimination of stellar content
mapping of both stars, by type, and extinction
Numbers of catalogued emission line stars – by magnitude, north (Kohoutek/Wehmeyer) and south (Stephenson/Sanduleak):
North
South
a factor of ~1000 in depth being opened up
…notice the north/south contrast
north
south
IPHAS observing and data release
Definition of IPHAS:
IPHAS = INT Photometric H Survey of the Northern Galactic Plane
Telescope/instrument: INT/Wide Field Camera
Survey area: all northern Plane longitudes; latitude range –5o < b < +5o (1800 sq deg)
Magnitude limit (10): r’ = 20
Required observations:
H (120 sec),
Sloan r’ (30 sec) and i’ (10 sec)
at 2 overlapping pointings
Seeing: < 2 arcsec, median ~ 1.1 arcsec
The IPHAS Consortium:The IPHAS Consortium:
Janet Drew (PI)Janet Drew (PI)
Robert GreimelRobert Greimel
Mike Irwin, Nic Walton Mike Irwin, Nic Walton
Astronomers in the Isaac Newton Group countries: Astronomers in the Isaac Newton Group countries: the UK, Netherlands and Spainthe UK, Netherlands and Spain
……also in the USA, Australia, Germany (see also in the USA, Australia, Germany (see iphas.org)iphas.org)
(Contributions to talk: Andrew Witham, Danny Lennon, Antonio (Contributions to talk: Andrew Witham, Danny Lennon, Antonio
Hales-Gebrim, Stuart Sale)Hales-Gebrim, Stuart Sale)
The INT Wide Field Camera:
Mosaic of 4 CCDs – pixel size 0.33”x0.33” – area imaged ~0.25 sq deg
~7600 x 2 pointings (5 mins per pointing)
……filling the filling the northern Plane:northern Plane:
(a section of the IPHAS pointing map at l = 75o)
To cover 1800 sq.degs, twice
22 clear weeks
Next slides: 2003 – 2005 IPHAS data-taking sequence (~60% achieved in this time):
200+ nights observing effort, via standard PATT/CAT/NFRA time allocations
Likely completion: end 2007Likely completion: end 2007
Status end 2006:- 72% at < 1.7 arcsec seeing, 80% < 2.0 arcsecStatus end 2006:- 72% at < 1.7 arcsec seeing, 80% < 2.0 arcsec
IPHAS data release:
Reduced images already available from CASU
Early release of point source catalogue: 2003-2005 data, (~60% of survey, nightly calibration – not yet uniform)
Aiming for photometrically uniform catalogue, and public-domain ‘H Atlas’
~200 million objects, due by end July ‘07
IPHAS science
• A brief word on nebulae
• Emission line stars: how to find them, preliminary catalogue, and one example rarity
• Exploitation of the main stellar locus in the (r’-H, r’-i’) plane
Extended sources: nebulae
HH r’r’ i’i’
HH point point source source (CS)(CS)
The Prince’s Nebula (Mampaso et al 2006)The Prince’s Nebula (Mampaso et al 2006)
……deeper optical image:deeper optical image:
CaII IR triplet – in CaII IR triplet – in central star spectrum:central star spectrum:
A low-density old A low-density old nebula….nebula….
-- at large -- at large Galactocentric Galactocentric distance (13.4 kpc)distance (13.4 kpc)