Vincenzo Ripepi INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy Collaborators:

1. Vincenzo Ripepi INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy Collaborators: J.M. Alcalá, F.Cusano, M. Marconi (INAF-OAC) LOI partecipants EXOdat team Young open cluster in the vicinity of COROT primary targets: the case of Collinder 96 and Dolidze 25

2. HD171834 HD43587 HD170580 HD181555 HD49933-HD49434 HD177552 HD49434 HD52265 Motivation Primary interest the search for PMS  Scuti candidates for COROT  Interest for young open cluster (age < 10 Myr) in the vicinity of COROT Primary targets, i.e. observed in any case in the EXO field.

3. Collinder 96 • Young cluster (age~10 Myrs); only 12 stars observed by Moffat & Vogt (1975) • No association with SFR or OB • Unfortunately no info on membership. •  • New observations carried out during winter 2004 with the 1.5m Loiano telescope (Italy). • UBVR-H filters for a FOV of ~ 14’x13’. • Data reduction performed with DAOPHOTII/ALLFRAME (Stetson, 1987, 1993).

4. CMD for Collinder 96 • Preliminary Conclusions: • Collinder 96 is probably not as young as found in previous works (Age ~ 60 Myrs) • Quite large uncertaintis due to the lack of membership information • improvements are expected by the study of new proper motion measurement (UCAC2) • Echelle spectra for brightest stars scheduled (Loiano). Isochrones by Girardi et al. 2000

5. Dolidze 25: what we know up to now • Dolidze 25 is associated with the HII region S284 • it should be young (< 10 Myrs, Turbide & Moffat, 1993) • it is far (heliocentric distance > 5.5 Kpc) • Only UBV photometry in the literature for the brighest stars (Moffat & Vogt, 1975) + slighly deeper UBV CMD on a small region (Turbide & Moffat, 1993). • Spectral classification for some 30 stars (Babu, 1983), but not very precise. • Lennon et al. 1990 on the basis of high resolution spectroscopy for three OB stars, have found that Dolidze 25 is deficient in metals approximately by a factor 6 (i.e. ZDolidze25 0.003, similar to SMC)  somewhat in disagreement with respect to the expected abundance gradient of the disc.

6. Additional motivations for Dolidze 25 • Martin et al. 2004 claimed the discovery of a dwarf galaxy remnant in Canis Major: the fossil of an in-plane accretion on to the Milky Way. Dolidze 25 position correspond to the one of the Canis Major object “Dolidze 25 …. could be the consequence of the strong perturbation of the disc by the accreted dwarf Galaxy and the resulting star formation activity in the disc.”  a detailed study of this cluster could allow us to verify this statement • Dolidze 25 is poorly studies as a SFR. Due to the low metallicity, it represent an ideal object to study matal deficient PMS objects, which would be the counterpart of “normal” TTauri and (hopefully) intermediate mass PMS. • Dolidze 25 has a good probability to fall in the EXO field of COROT  characterization of stars of the cluster (spectra!) needed  proposal to obtain EXO planet windows to study interesting candidates. • Spectral classification (using spectra) for a relevant number of stars  important to check the photometric classification by EXO planet team (see Magali’s talk).

7. Efforts to study Dolidze 25 • UBVR-H imaging (20’x20’ FOV) on the north-east of the cluster (Loiano, 1.5m telescope). Data not fully reduced and not presented here. • VIMOS proposal in collaboration with J.M. Alcalá (Naples): multiobject spectroscopy on two pointings centered on Dolidze 25: • ACCEPTED! •  • How to select targets for spectroscopy? •  • Literature not sufficient (few IRAS, ROSAT sources…) Need for a reliable HR diagram on a wide area. •  • VIMOS pre-imaging in R and I + EXO planet preparatory program photometry (FUNDAMENTAL!)

8. 18’x17’ Membership by Dias, Lèpine, Alessi (2002)

9. Data reduction • Preliminary data reduction of VIMOS pre-imaging data using Sextractor (Bertin, 1999) • Cross-correlation with EXOdat observations  photometric calibration and marging of the catalogues (VLT data deeper, but saturation problems below I=13)

10. CMDs from EXOdat

11. 20 Mo 6 Mo 3 Mo 0.8 Mo Cluster parameters • We know from the literature the approximate distance and reddening • From Lennon et al. (1990) we know logTe and logg for three bright stars. •  • We can use all these info to constrain the age of the cluster by using the isochrones (Padua group: Girardi et al. 2000). • Hints on PMS star position in HRD by using the Siess et al. (2000) tracks and Isochrones (6 Myr).

12. I (R-I) Target selection Cignoni & Degl’Innocenti, Private Comm.

13. VIMOS multiobject spectroscopy • Two different grisms: • Medium Resolution: 2 Å/pixel (spectral reange 5050-8700 Å)  up to 50 slits per CCD, i.e up to 200 per exposure • High Resolution Red: 0.6 Å/pixel (spectral reange 6350-7500 Å)  > 40 slits per CCD, i.e up to 170 per exposure •  • ~ 900 spectra with MR grism  spectral classification • ~ 550 spectra with HR_red grism  study of PMS stars (if any!)

14. Conclusions • A few open clusters will probably fall in the EXO field of COROT. • Collinder 96 and Dolidze 25 were selected to be studied on the basis of the their supposed young age and low crowding. • Collinder 96 probably not very young; near a low priority primary target. • Dolidze 25 is a very interesting object under many point of views. • Our data confirms that Dolidze 25 is young age ~ 4-10 Myrs • Multiobject spectroscopy with VIMOS@VLT scheduled  results (hopefully) at CW9 (spring 2005).