1. VIMOS@VLT observations of Dolidze 25
Vincenzo Ripepi
INAF-Osservatorio Astronomico di Capodimonte, Naples, Italy
Collaborators:
J.M. Alcalá, F.Cusano, M. Marconi (INAF-OAC)
LOI partecipants-PMS collaboration
EGBW

2. Primary interest the search for PMS  Scuti candidates for COROT
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. Dolidze 25: Properties
Dolidze 25 is a young cluster associated with the HII region S284
it is far (heliocentric distance > 5.5 Kpc)
it is metal poor: Lennon et al found that Dolidze 25 is deficient in metals approximately by a factor 6  somewhat in disagreement with respect to the expected abundance gradient of the disc.
Dolidze 25 could be connected with the Canis Major Dwarf Galaxy which is supposed to be merging with our Galaxy
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 intermediate mass PMS.
Spectral classification (using spectra) for a relevant number of stars  useful for characterize stars in the exo field.

4. Observations: Imaging
Observations in RI with (pre-Imaging data)
Data reduction using psf photometry DAOPHOT/ALLSTAR (Stetson 1987)
Accurate photometric calibrations using Stetson’s extension of Landolt (1992) standards.
Pre-Imaging (+2MASS data+EGBW data) used to select targets for the spectroscopy. High priority to objects showing IR excess.
Galactic model by Cignoni & Degl’Innocenti, Private Comm.

5. Observations:multiobject spectroscopy
Medium Resolution: 2.5 Å/pixel (spectral reange Å)  up to 50 slits per CCD, i.e up to 200 per exposure
High Resolution Red: 0.6 Å/pixel (spectral reange 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!)
Preliminary data reduction with ESO VIMOS pipeline (but no defringing, bad sky subtraction for HR and strange features in Q3 for MR)
100% MR spectra extracted
50% HR spectra extracted

6. Results: the HR diagram

7. Results: spectra

8. Results: spectra

9. Results: spectra

10. Results: spectra

11. Conclusions and future actions
Dolidze 25 show a rich population of H emission young stars
A few objects are PMS intermediate mass candidates. Four stars fall within the instability strip for PMS  Scuti pulsation
faint objects: but for R~16.5 mag we should be able to do asteroseismology for PMS  Scuti candidates
no problem to study mid/long term variations (UX Ori like)
Several bright KM stars with (and without) H emission
In the future we plan to:
reduce better the data + calibration in flux
obtain spectral classification for all the stars
study membership (UCAC2)
time series photometry for interesting objects – not easy, faint objects
Preparation of proposal in the AP context asking for a few windows in the EXO field.
PMS collaboration
Open to everybody: if you are interested please contact me: