Rosaria (Sara) Bonito

Dipartimento di Fisica e ChimicaUniversita' degli Studi di Palermo

INAF-Osservatorio Astronomico di Palermo

THE PROBLEMS OF SKY SUBTRACTION

AND OF ANOMALOUS MEMBERS IN YOUNG CLUSTERS:

THE CASE OF NGC 6611

FLAMES observations (HR15N setup)

NGC 6611: forthcoming observations

GES

NGC 6611 & GES

(Bonito et al. 2013)

Nebular contribution to Ha emission

Strongly varying in space and time Narrower than stellar

FWZI method (as EW and Ha10% cannot be derived)

SKY SUBTRACTION & Ha

FWZI METHOD (1) Zoom +/- 3 A around Ha in sky spectra

FWZI METHOD (2) Normalize: spectrum without the emission line

FWZI METHOD (3) Difference or ratio original

spectrum/spectrum without the emission line

FWZI(Ha) skyFWZI METHOD (4)

< 3 A

FWZI(Ha) star >> FWZI(Ha) sky

FWZI(Halpha) & ACCRETION

(Bonito et al. 2013)

Upper limit for EW(Li) using other features in the Li spectral region (Randich et al. 2009)

Median sky subtraction (Jeffries & Oliveira 2005)

SKY SUBTRACTION AND Li (1)

Spurious absorption lines due to [SII] 6717 A

SKY SUBTRACTION AND Li (1)

SKY SUBTRACTION AND Li (2)

No Li No veiling

Age Membership

NGC 6611: forthcoming observations

g Vel

NGC 2264

NGC 6530

IMPLICATION FOR GES

BWE STARS IN NGC 6611 (Bonito et al. 2013)

+: members from the Guarcello et al. (2010) catalog

: all the targets observed with FLAMES

: BWE stars (with disk)

BWE STARS: WHY?

> 50 %: members(Bonito et al. 2013)

old members? (De Marchi, Panagia, Guarcello, Bonito et al. 2013)

also in other clusters

completeness

age spread?

GES

CONCLUSIONS

Sky subtraction FWZI(H ) a method Spurious absorption lines (Li)

Blue with excesses (BWE) stars completeness age spread other clusters (GES)