Planetary Nebulae and HII as probes of the evolution of Local Group galaxies A.Y. Kniazev (SAAO), S.A. Pustilnik (SAO), E.K. Grebel (ARI) and many others September 2009 SAO RAS

Plan Introduction: Reasons to study extragalactic PNe/HII Examples of some nearby dIrr galaxies: PNe and HIIs PNe in M31 with SDSS data: The method of using SDSS data New M31 PNe Sample of PNe in M31 Andromeda NE as progenitor of stream

HII Regions HII regions are regions where active star-formation in galaxies is currently located (gas is heated by massive stars).

Planetary Nebulae (PNe)

HII\PN

Some reasons to study extra-galactic PNe/HII (1)‏ PNe/HII as chemical probes of galaxies – the emission lines can provide nebular abundances: for PNe - related to those of the progenitor star; for HII - ISM from which massive stars were formed. PN in Fornax dSph (Distance = 140 kpc) V=18.9 mag – 2x30 min with NTT 3.5m telescope: O, Ar, N, Ne, S, Cl, Fe, He and C with accuracy 0.02 – 0.20 dex PN in Sextans A (Distance = 1400 kpc) V=22.4 mag – 3x30 min with NTT: O, Ar, N, S, He with accuracy 0.05 – 0.25 dex 2 stars (V=17.3 mag) from NGC6822 (Distance = 490 kpc) 3x1 h for each with 10m Keck telescope: O, Si, Sc, Ti, Cr, Fe, Ni with accuracy dex

HII/PNe as chemical probes Maciel, Lago & Costa (2006, A&A, 453, 587)‏

Some reasons to study extra-galactic PNe/HII (2)‏  PNe/HII as kinematic probes – (1) since PNe are just ordinary stars that we happen to catch at the ends of their lives, they are fairly representative of the bulk stellar population of the galaxy; (2) HII regions - hot gas  PNe as a secondary distance indicator – photometry of the [O III] λ5007 Å emission line showed that the luminosity function of the PN population in a galaxy has a characteristic shape.

Examples of PNLF Herrmann et al. (2008 ApJ, 683, 630)‏

Sextans A Type dIrr V Distance 1.45 Mpc (Sakai et al. 1996)‏ 12+log(O/H)=7.49 ± 0.3 from HII regions spectra (Skillman et al. 1989)‏ One PN from (Jacoby & Lesser 1981, Magrini et at. 2003)‏ Picture from Magrini et al. (2004)‏

Sextans A: From Kniazev et al. (2005, AJ, 130,1558)‏

Sextans B Picture from Magrini et al. (2004)‏ dIrr IV-V Distance 1.32 Mpc from Sakai et al. (1997)‏ 12 + log (O/H)=7.56 from HII regions (Skillman et al. 1989)‏ Number of PNe: 5 (Magrini et al. 2002)‏

Sextans B: From Kniazev et al. (2005, AJ, 130,1558)‏

Sextans A and B: Kniazev et al (2005) + Magrini et al. (2005)

Distribution of abundances in Sextans B Do we see negative gradient of abundances in Sextans B? Result of accretion event? Or interaction?

IC10 7 PNe candidates were observed with 6m SAO RAS telescope in 2004,2006 altogether with many HII regions dIrr IV/BCD Distance: Mpc 16 PNe candidates from Magrini et al. (2003)‏ 30x30 arcmin → 9 additional PNe candidates were found by Magrini & Consalves (2009) In the central area 5x5 arcmin

PNe in IC10 (SFH) The best fir of SF history for the HST field from Zucker (2001). Taking into account: - all observed PNe in IC10 are stars formed 7-10 Gyr ago - amount of PNe is proportional to the total mass of stars was born during of certain epoch - PN relates to ~2·10^6 Msun ↓↓ SFR ~ Msun/year during 7-10 Gyr ago

Sloan Digital Sky Survey (SDSS)‏ Imaging in drift-scan mode (ugriz)‏ Spectroscopic (R ~ 2000) survey: - all galaxies up to r= QSOs Data are processed and located in the database Covers >1/4 of the sky.

SDSS Observations of M31 Data obtained 5 October 2002 (Runs 3366 and 3367) in 3 hours Two overlapping strips oriented along the major axis of M31, covering an area of 18˚x2.5˚ From Dan Zucker

SDSS Stellar Density Distribution (1) Stellar structure ~3° to NE; (2) At approximately same distance as M31; (3) Radius ~30'; (4)  0,V = 28.6 and MV = -12.4; (5) Satellite or stream? (6) Can have 0.5 – 2 PNe From Zucker et al. (2004)

Emission Objects with SDSS Is it possible to select PNe candidates using SDSS data?

Selection Criteria for PNe candidates Identification of PNe from Nolthenius & Ford (1987) and from Jacoby & Ford (1986): 30 were identified with position accuracy < 1″ From Kniazev et al. (2009a, in preparation) We then applied all these criteria to the whole area of M31 as scanned by SDSS We also applied the same selection criteria to extended objects (90% at r = 21.6)‏ All selected candidates were visually verified for the false selections (difraction spikes) Finally, we selected 230 PNe candidates: 102 PNe candidates of the first priority and 128 PNe candidates of the second priority

PNe canidates in the Outer Part of M31 Candidates positions traced different substructures of outer part of M31 3 candidates in the area of Andromeda NE have been found !!!

Spectral follow-up Observations(1)‏ 2.2m telescope at Calar Alto (Spain); CAFOS; 4200–7800 Å, ~1.9 Å/pix;  8 nights in October 2004 under variable weather conditions;  15–30 min exposures;  Totally 80 candidates from 230 were observed with efficiency of ~88% for our method The selection method is very efficient !

Last decade: M31 Deep panoramic survey with the Isaac Newton Telescope (2.5m) Wide Field Camera (~0.29 sq.deg)‏ ( Ferguson et al. 2002); V and i filters + Keck DEIMOS multiobject spectrograph (in total ~2800 stars): Ibata et al. (2005) + Wide-field camera of CFHT (Ibata et al. 2007)‏ g and i filters

Last decade: PNe in M31 (1) December Hurley-Keller et al. (2004): 136 PNe selected with narrow-band imaging and observed with WIYN Hydra fiber spectrograph (2) Halliday et al. (2006): 723 PNe in the disk and bulge – narrow-band imaging and spectroscopy with fibre-fed spectrograph at WHT (LA Palma)‏ (3) Merret et al. (2006): 2615 PNe selected with PN.S at WHT

Velocity distribution with PNe Some PNe were identified by Merrett et al. (2003, 2006) as a possible continuation of the merging Southern Stream of stars (Ibata et. 2001,2004) No HI in the region of And NE

Is And NE the core or remnant of the progenitor of this stream ?

Spectral Observations of selected PNe 3.5m telescope at Calar Alto (Spain); TWIN; 3500–7500 Å, ~1 Å/pix (FWHM ~ 5Å);  4 (3) nights in August 2005 under variable weather conditions;  Total exposures 45–60 min;  Totally 9 PNe were observed  6m telescope (SAO; Russia); SCORPIO; Å, ~2.5 Å/pix  1 additional PN in Andromeda NE From Kniazev et al. (2009b, in preparation)

And NE is the core or remnant of the progenitor of the stream (1)‏

How bright was And NE before? (1)‏ From Magrini et al. (2003)‏ In total 22 PNe are selected as members of this stream M(V) ~ Was comparable to NGC205!

How bright was And NE before? (2)‏ From Kunth & Ostlin et al. (1999)‏ From LZ ratio for dEs M(B) = Was comparable to NGC205! > 90% of stars was lost?

Model From Fardal et al. (2007, MNRAS, 380, 15)

The End