Artículo
First confirmed ultra-compact dwarf galaxy in the NGC 5044 group
Faifer, Favio Raúl
; Escudero, Carlos Gabriel
; Scalia, María Cecilia
; Smith Castelli, Analia Viviana
; Norris, Mark; de Rossi, Maria Emilia
; Forte, Juan Carlos
; Cellone, Sergio Aldo
Fecha de publicación:
03/2017
Editorial:
EDP Sciences
Revista:
Astronomy and Astrophysics
ISSN:
0004-6361
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
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: In Gemini+GMOS deep images of several fields around NGC 5044 and in spectroscopic multi-object data of one of these fields, we detected an unresolved source with g′ ~ 20.6 mag, compatible with being an UCD. Its radial velocity was obtained with FXCOR and the penalized pixel-fitting (pPXF) code. To study its stellar population content, we measured the Lick/IDS indices and compared 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 that agrees with the velocity of the elliptical galaxy NGC 5044. 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 most likely an extreme GC (MV ~ −12.5 mag) belonging to the GC system of the elliptical galaxy NGC 5044.
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Articulos(CASLEO)
Articulos de COMPLEJO ASTRONOMICO "EL LEONCITO"
Articulos de COMPLEJO ASTRONOMICO "EL LEONCITO"
Citación
Faifer, Favio Raúl; Escudero, Carlos Gabriel; Scalia, María Cecilia; Smith Castelli, Analia Viviana; Norris, Mark; et al.; First confirmed ultra-compact dwarf galaxy in the NGC 5044 group; EDP Sciences; Astronomy and Astrophysics; 599; 3-2017; 1-4; L8
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