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)

-- low metallicity -- low metallicity progenitorprogenitor

-- a Type I PN (with -- a Type I PN (with He/H=0.13, N/O=1.8)He/H=0.13, N/O=1.8)

-- with an interacting -- with an interacting binary central star?binary central star?

Corradi, Mampaso, Corradi, Mampaso, Viironen, Sabin, Viironen, Sabin, Parker, Morris…Parker, Morris…

First aim: to get out an First aim: to get out an RA 18—20 hrs list of RA 18—20 hrs list of nebulaenebulae

……mainly finding low mainly finding low surface brightness surface brightness resolved nebulae, resolved nebulae, including interesting including interesting anticentre candidatesanticentre candidates

Another PN discovery: IPHAS + [OIII] Another PN discovery: IPHAS + [OIII] combined ~100x100 arcseccombined ~100x100 arcsec22 image image

(Nick Wright, UCL)(Nick Wright, UCL)

Emission line stars

Where emission line stars are in the IPHAS (r’-H,r-i’) colour-colour plane:

Main stellar locus

from Drew et al 2005 (survey paper)

(EW)

(EB-V)

High-confidence H

High-confidence H emitte

rs

emitters

The preliminary conservatively-selected emission line star catalogue:

Witham et al, to be submitted

~5000 objects

New catalogue (in red) compared with Kohoutek and Wehmeyer 1999 (in black)

Distribution of conservatively selected emission line objects:

Black: r’ > 18

Red: 13 < r’ < 18

Green: area surveyed so far

Distribution against Galactic latitude of:

Conservatively-selected emission line objects (top)

Premium sample of stars, with repeat/consistent photometry (middle)

Emitters/premium (bottom)

confirms warp

Distribution against Galactic longitude:

Top – emitters

Middle – premium sample

Bottom – emitters/premium

Spectroscopic follow up

….MMT/HectoSpec, FAST, La Palma ITP

e.g. 2 MMT/HectoSpec selections (up to 300 fibres in a 1-degree field)

(Cyg OB2 centre) (DR15, 0.7o south)

((redred = H = H emitter, emitter, blueblue = spectrum obtained) = spectrum obtained)

Long-slit follow-up: an extreme rarity, and a mystery… IPHAS J0214…

r’ = 12.9, spectrum dominated by He and Fe lines …both broadened stellar, and narrow nebular, components

Discovery spectrum obtained using FAST

A class of two? J0214 (bottom) and HDE 326823, Be!pec (top)

(Lennon et al – in prep.)

Near-MS A stars and more

(Direct exploitation of IPHAS photometry)

The power of the IPHAS (r’-Ha, r’-i’) plane:

(i) The main sequence, as it reddens, sweeps out area;

(ii) Emission line stars, M dwarfs, M giants, white dwarfs, and near-MS A stars are all easily selected.

Near-MS A star selection from IPHAS colour-colour plane:

• (r’-H) ~ 0.025 along bottom of main locus captures A0-5 sub-types

• colours metallicity insensitive

• representative M(r’) ~ 1.5 for A0-5 field stars at ages > 5 - 10 Myrs

long sightlines achieved

Uses:- Uses:-

(i)(i) hunting A dwarfs in their own righthunting A dwarfs in their own right

(ii)(ii) accessing a simple/common (almost) accessing a simple/common (almost) standard candlestandard candle

Selecting near-MS A stars

…..a control experiment: the 5-10 Myr old open cluster NGC 7510

expected distance modulus and reddening

An A dwarf census – in IPHAS and Spitzer GLIMPSE overlap area

Question:- how many A0-5 dwarfs show mid-IR (Vega-like) dust excesses?

Hales-Gebrim, 2007 PhD thesis

Method: select, deredden using IPHAS, then examine IR colours/SED

The answers:

Searching 13.5 < r’ < 18.5,

23050 candidate IPHAS A stars in GLIMPSE overlap region

3062 of these come with 2MASS magnitudes, IRAC detections in >2 bands

At 8 m, 1.1% have dust excesses

At 24 m, 1.2% have excesses

…only 10 at both wavelengths

Mapping Cyg OB2 and its cluster environment:

The big (how The big (how big?) OB big?) OB association association in Cygnus-X: in Cygnus-X:

IPHAS data IPHAS data for most for most central field, central field, with Awith AVV =4.5 =4.5

and Aand AVV = 7.0 = 7.0

MS tracks, MS tracks, superimposedsuperimposed

How are How are near-MS A near-MS A stars stars distributed? distributed?

A stars in and around Cyg OB2:

21 field overlaps shown

Dereddened magnitudes

Blue circles:-

12 < r’0 < 12.5

Smaller black dots

12.5 < r’0 < 13

(Purple box = 2MASS stellar density peak)

Towards full exploitation of the photometry: Towards full exploitation of the photometry:

3D extinction mapping

An algorithm that, for all stars in main locus, An algorithm that, for all stars in main locus, takestakes

r’, r’-i’, r’-Hr’, r’-i’, r’-H

……. to obtain spectral type, reddening and . to obtain spectral type, reddening and distancedistance

Two examples of reddening as a function of distance

Top: l,b = 34,+4

Bottom: l,b = 34,+2

Coloured lines: results from published extinction models

Schlegel et al limiting extinction

(Stuart Sale, PhD project underway)

Related surveys:

UVEX: u’, g’, r’ across the northern Plane

VPHAS+: u’, g’, r’, Ha, i’ across the southern Plane (VST public survey – 2009? start)

UKIDSS/GPS: J, H, K, mainly across northern Plane

VISTA VVV and VHS: z, Y, J, H, K (public surveys – 2008 start)

Closing Remarks

• Narrowband H, with other broadband filters confers much diagnostic power for both emission line stars, and normal populations

• The northern Galactic plane is soon to have been surveyed down to ~20th magnitude (the south to follow…)

• IPHAS EDR soon to be launched – please visit at iphas.org!

The shape of things to come: combining IPHAS and The shape of things to come: combining IPHAS and UKIDSS/GPS data –UKIDSS/GPS data –

(due to Eduardo Gonzalez-Solares, CASU, IOA)(due to Eduardo Gonzalez-Solares, CASU, IOA)

IPHAS + GPS

Above – as it comes (the Above – as it comes (the price of nightly price of nightly calibration only)calibration only)

Right – after photometric Right – after photometric realignmentrealignment

IPHAS + GPS

Two example c-c Two example c-c planes, with synthetic planes, with synthetic trackstracks