Instituto de Astrofìsica de Canarias Photometric and spectroscopic properties of stellar populations in the Carina dSph galxy M. Monelli Instituto de Astrofìsica de Canarias Concepcion, Jan 8-14, 2007

dSph/dE dSph/dIrr dIrr Spirals S. Hidalgo

An example: the field of IC1613 Rt~15' ACS

An example: the field of IC1613 Rt~15' I. Drozdovski ACS + Subaru

An example: the field of IC1613 Rt~15' ACS + Subaru CFHT

(m-M)0 D(Kpc) Mv (TO) Rcore (') Rtidal (') Galaxy satellites 18.5-22 50-250 22.5-26 6-16 10-80(?) M31 satellites 23.5-24.5 500-800 27-28.5 <3 5-17 Isolated <26 <1600 <30 <5 North telescope Mirror (m) Obs type F.o.v. SuprimeCam SUBARU 8 Imaging 30'x24' PrimeFocus WHT 4.2 16'x16' MegaCam CFHT 3.6 1°x1° WFC INT 2.5 34'x34' South VIMOS VLT Ima/spec 16'x18' MOSAICII CTIO 4 36'x36' WFI 2.2 ESO 2.2 33'x34' FORS1/2 7'x7' FLAMES Spec 25'x25' ACS HST 2.4 imaging 3'x3'

TO star, Mv~3.5 D~200Kpc, (m-M)=21.5  mv(TO)~25 D~2Mpc, (m-M)=26.5  mv(TO)~30 D~770Kpc, (m-M)=24.5  mv(TO)~28 S. Hidalgo

Use different approaches! 4m telescopes + wide-field imagers 8m telescopes + medium-field cameras HST + spectroscopy (8m + multi-object spect.) Global understanding of the properties of nearby galaxies (SFH, variables, radial gradients, tidal interactions…)

WIDE FIELD OBSERVATIONS!! Carina: Observational issues 1°x1° DSS Extended low surface brightness low central density (m-M)0 ~ 20.15 D ~ 100 Kpc Mv ~ -9.3 Rcore ~ 9 Rtidal ~ 29 (47’) (Mateo 1998) WIDE FIELD OBSERVATIONS!!

Why Carina? complex star formation history (Smecker-Hane et al. 1996) ( mix of stellar populations) recent episode (<1Gyr) (Monelli et al. 2003) sizable sample of variable stars (Dall’Ora et al. 2003) high M/L ( ~30 M☼ /L☼)  DM? controversial evidence of extra-tidal stars: tidal interactions with the Galaxy or extended halo ? (Hayashi et al 2003, Kazantzidis et al 2004, Monelli et al. 2004, Munoz et al. 2006)

The Carina Project: Long term photometric and spetroscopic project aimed at studying the stellar content of the Carina dSph galaxy G. Bono, R. Buonanno, V. Castellani, C.E. Corsi, F. Caputo, L. Pulone (INAF-Rome Obs.) A.R. Walker (CTIO) M. Dall’Ora, V. Ripepi (INAF-Capodimonte Obs.) A. Munteanu (Univ. Pompeu Fabra) P.B. Stetson (DAO) H.A Smith (MSU) A. Aparicio, C. Gallart (IAC) M. Nonino (INAF-Trieste) F. Thévenin (Nice Obs.) P. Francois (Paris Obs.)

CAREFUL WITH THE CALIBRATION!! The data set: central region Instr. f.o.v. Filter Tot.exp. Date 2.2m ESO 32x33 60 B 30,500s 5-7 Jan 2000 0.23/px 63 V 30,300s + archive CTIO 4m 36x36 54 B 21,200s 19 Dec 1999 0.27/px 54 V 13,000s 8-9 Jan 2000 22 U 22,000s Dec 2004 19 I 5,700s Jan 2005 Photometric reduction with DAOPHOTII/ALLFRAME (Stetson 1987, 1994)  ~2,900 frames CAREFUL WITH THE CALIBRATION!! WARNING!!!

Results: color-magnitude diagram ~30000 stars (|sharp|<0.2) DM = 20.24 E(B-V) = 0.03 Z = 0.004 [Fe/H] = -1.7  isochrones superposition: Old population ~11Gyr Intermediate pop. ~3-7 Gyr Young pop ~0.6-1 Gyr

Results: spatial distribution The intermediate-age stellar population is more concentrated toward the centre; old stars are distributed in a sort of diffused halo. The peak of the distribution of the old stars is offset by ~2´.

Spectroscopic data sets GIRAFFE RA DEC λ(nm) exp time (hr) tot # stars 1 06:41:37 -50:57:58 LR8 820-940 (CaT) R~6500 18 ESO archive 1100 (RGB, AGB + field) 2 06:41:00 -50:45:06 15 3 06:42:51 -50:52:50 10 4 06:39:50 -51:04:00 7.5 5 06:42:05 -51:10:00 16 FORS2 A 06:42:03 -50:54:00 1028z (CaT) 773-930 2.6 330 (RGB,HB,MS, TO, variables + field) - 1400V 456-586 (Mg triplet) R~2000 2.9 B 06:42:00 -50:50:30 C 06:41:38 -50:55:34 D 06:41:26 -51:57:30 E 06:40:51 -51:07:56 1.3

Complementary samples FLAMES (archive): based on EIS photometry (Koch et al. 2006) FORS2: based on our photometry Complementary samples

Two main questions: 1) Do the different populations present different kinematical properties? 2) Is there any spread in the chemical composition among different populations?

WARNING!! FLAMES: Uncertainties in sky subtraction: partially masked in the vr determination but show up with the individual abundance determination FORS2: day/night mask positioning  abundances Centroid positioning in the slit  vr

Work in progress… Different peak?? Hidden systematics?? FLAMES (1095) FORS2 (150) Work in progress… Different peak?? Hidden systematics??

Variable Stars Multiple stellar populations  different families of variable stars present in the same system, both in H- and He-burning phases Bright variables as tracers of stellar populations

19 Anomalous Cepheids

79 RRLyrae 19 Anomalous Cepheids

13 binaries 79 RRLyrae 19 Anomalous Cepheids

270 candidates/unclassified 13 binaries 79 RRLyrae 19 Anomalous Cepheids

Outer fields: tidal tails? We observed selected regions around Carina. Deep images were collected in order to use Main Sequence stars as tracers of the stellar content. C, D 30' B 52' E 60' A 1.5 ˚ α, β 2˚ γ 4.5˚ CTIO 4m 2.2m ESO

Conclusions USE DIFFERENT APPROACHES!!