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(Ha) method Spurious absorption lines (Li)
Blue with excesses (BWE) stars completeness age spread other clusters (GES)