INVESTIGADORES
CELLONE Sergio Aldo
artículos
Título:
First confirmed ultra compact dwarf galaxy in the NGC 5044 Group
Autor/es:
FAIFER, F. R.; ESCUDERO, C. G.; SCALIA, M. C.; SMITH CASTELLI, A. V.; NORRIS, M.; DE ROSSI, M. E.; FORTE, J. C.; CELLONE, S. A.
Revista:
ASTRONOMY AND ASTROPHYSICS
Editorial:
EDP SCIENCES S A
Referencias:
Lugar: Paris; Año: 2017 vol. 599 p. 1 - 4
ISSN:
0004-6361
Resumen:
Context. Ultra compact dwarfs (UCDs) are stellar systems displaying colours and metallicities between those of globular clusters (GCs) and early-type dwarf galaxies, as well as sizes of Reff <~ 100 pc and luminosities in the range -13.5 < Mv < -11 mag. Although their origin is still subject of debate, the most popular scenarios suggest that they are massive star clusters or the nuclei of tidally stripped dwarf galaxies.Aims. NGC 5044 is the central massive elliptical galaxy of the NGC 5044 group. Its GC/UCD system is completely unexplored.Methods. We obtained deep images of several fields around NGC 5044 with Gemini+GMOS, as well as an spectroscopic mask of one of these fields in multi-object mode. From the photometric analysis of the images we detected an unresolved source with g´ ∼ 20.6 mag, compatible with being an UCD. To obtain its radial velocity we used FXCOR and the penalized pixel fitting (pPXF) code. To study its stellar population content, we have applied two methods: we measured the Lick/IDS indices comparing them with predictions of single stellar population models, and we used the full spectral fitting technique.Results. The spectroscopic analysis of the UCD revealed a radial velocity in agreement with that of the elliptical galaxy NGC 5044. In addition, from the Lick/IDS indices, we have obtained a luminosity weighted age and metallicity of 11.7(+1.4-1.2) Gyr and [Z/H] = -0.79 +/- 0.04 dex, respectively, as well as [α/Fe] = 0.30 ± 0.06. From the full spectral fitting technique, we measured a lower age (8.52 Gyr) and a similar total metallicity ([Z/H] = −0.86 dex).Conclusions. Our results indicate that NGC 5044-UCD1 is likely an extreme (MV ∼ −12.5 mag) GC belonging to the GC system of the elliptical galaxy NGC 5044.
