1. 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: N. Wright UCL)

2. Talk Outline Introduction/motivation IPHAS – the survey IPHAS science Conclusion (i)Nebulae (ii) Emission line stars (iii) Stellar populations from the photometry

3. 1. 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. 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 H  at 1 arcsec resolution

4. Reasons (continued) 3. 3.To trace the structure of the Galactic disk  H  = star-formation indicator  emission line stars as spiral arm tracers 4. 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

5. 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

6. IPHAS observing and data release

7. 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 –5 o < b < +5 o (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

8. The IPHAS Consortium: Janet Drew (PI) Robert Greimel Mike Irwin, Nic Walton Astronomers in the Isaac Newton Group countries: the UK, Netherlands and Spain …also in the USA, Australia, Germany (see iphas.org) (Contributions to talk: Andrew Witham, Danny Lennon, Antonio Hales-Gebrim, Stuart Sale)

9. 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)

10. …filling the northern Plane: (a section of the IPHAS pointing map at l = 75 o )

11. 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

26. Likely completion: end 2007 Status end 2006:- 72% at < 1.7 arcsec seeing, 80% < 2.0 arcsec

27. 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

28. 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

29. Extended sources: nebulae

30. HHHHr’i’ H  point source (CS) The Prince’s Nebula (Mampaso et al 2006)

31. …deeper optical image:

32. CaII IR triplet – in central star spectrum: A low-density old nebula…. -- at large Galactocentric distance (13.4 kpc) -- low metallicity progenitor -- a Type I PN (with He/H=0.13, N/O=1.8) -- with an interacting binary central star?

33. Corradi, Mampaso, Viironen, Sabin, Parker, Morris… First aim: to get out an RA 18—20 hrs list of nebulae …mainly finding low surface brightness resolved nebulae, including interesting anticentre candidates Another PN discovery: IPHAS + [OIII] combined ~100x100 arcsec 2 image (Nick Wright, UCL)

34. Emission line stars

35. 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) (E B-V ) High-confidence H  emitters

36. 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)

37. Distribution of conservatively selected emission line objects: Black: r’ > 18 Red: 13 < r’ < 18 Green: area surveyed so far

38. 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

39. Distribution against Galactic longitude: Top – emitters Middle – premium sample Bottom – emitters/premium

40. 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, 0.7 o south) (red = H  emitter, blue = spectrum obtained)

41. 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

42. A class of two? J0214 (bottom) and HDE 326823, Be!pec (top) (Lennon et al – in prep.)

43. Near-MS A stars and more (Direct exploitation of IPHAS photometry)

44. The power of the IPHAS (r’-Ha, r’-i’) plane: (i) (i)The main sequence, as it reddens, sweeps out area; (ii) (ii)Emission line stars, M dwarfs, M giants, white dwarfs, and near-MS A stars are all easily selected.

45. 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:- (i)hunting A dwarfs in their own right (ii)accessing a simple/common (almost) standard candle

46. Selecting near-MS A stars …..a control experiment: the 5-10 Myr old open cluster NGC 7510 expected distance modulus and reddening

47. 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

48. 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

49. Mapping Cyg OB2 and its cluster environment: The big (how big?) OB association in Cygnus-X: IPHAS data for most central field, with A V =4.5 and A V = 7.0 MS tracks, superimposed How are near-MS A stars distributed?

50. 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)

51. Towards full exploitation of the photometry: 3D extinction mapping An algorithm that, for all stars in main locus, takes r’, r’-i’, r’-H  …. to obtain spectral type, reddening and distance

52. 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)

53. 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)

54. 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 ~20 th magnitude (the south to follow…) IPHAS EDR soon to be launched – please visit at iphas.org!

56. The shape of things to come: combining IPHAS and UKIDSS/GPS data – (due to Eduardo Gonzalez-Solares, CASU, IOA)

57. IPHAS + GPS Above – as it comes (the price of nightly calibration only) Right – after photometric realignment

58. IPHAS + GPS Two example c-c planes, with synthetic tracks