1. 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

2. dSph/dE
dSph/dIrr
dIrr
Spirals
S. Hidalgo

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

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

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

6. (m-M)0 D(Kpc) Mv (TO) Rcore (') Rtidal (')
Galaxy satellites
50-250
6-16
10-80(?)
M31 satellites
<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'

7. 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

8. 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…)

9. 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!!

10. 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)

11. 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.)

12. 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!!!

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

14. 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´.

15. Spectroscopic data sets
GIRAFFE RA
DEC
λ(nm)
exp time (hr)
tot # stars 1
06:41:37
-50:57:58
LR8
(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)
2.6
330
(RGB,HB,MS, TO, variables
+ field) -
1400V
(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

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

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

18. 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

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

20. 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

21. 19 Anomalous Cepheids

22. 79 RRLyrae
19 Anomalous Cepheids

23. 13 binaries
79 RRLyrae
19 Anomalous Cepheids

24. 270 candidates/unclassified
13 binaries
79 RRLyrae
19 Anomalous Cepheids

25. 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

26. Conclusions
USE DIFFERENT APPROACHES!!