Bibcode
Lardo, C.; Pancino, E.; Mucciarelli, A.; Milone, A. P.
Referencia bibliográfica
Memorie della Societa Astronomica Italiana, v.84, p.228 (2013)
Fecha de publicación:
0
2013
Número de citas
0
Número de citas referidas
0
Descripción
Using UV images taken with the Telescopio Nazionale Galileo, we
discovered an anomalous sequence in the color-magnitude diagram of M 2.
This feature appears as a narrow poor-populated red giant branch, which
extends down to the sub giant branch region. We speculate that this new
feature could be the extension of the faint component of the split sub
giant branch recently discovered by Piotto et al. We identified in our
U,V images two CH stars detected in previous studies. These stars, which
are both cluster members, fall on this redder sequence, suggesting
indeed that the anomalous RGB should have a peculiar chemical pattern.
Unfortunately, no additional spectra were obtained for stars in this
previously unknown substructure.