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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Star formation in low density H-I gas around the elliptical galaxy NGC 2865

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Urrutia-Viscarra, F. [1, 2] ; Torres-Flores, S. [2] ; de Oliveira, C. Mendes [3] ; Carrasco, E. R. [1] ; de Mello, D. [4] ; Arnaboldi, M. [5, 6]
Total Authors: 6
[1] Southern Operat Ctr, Gemini Observ AURA, Casilla 603, La Serena - Chile
[2] Univ La Serena, Dept Fis & Astron, Ave Cisternas 1200 Norte, La Serena - Chile
[3] Inst Astron Geofis & Ciencias Atmosfer USP, Dept Astron, Rua Matao 1226, Cidade Univ, BR-05508090 Sao Paulo - Brazil
[4] Goddard Space Flight Ctr, Observat Cosmol Lab, Code 665, Greenbelt, MD 20771 - USA
[5] European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching - Germany
[6] INAF, Observ Pino Torinese, I-10025 Turin - Italy
Total Affiliations: 6
Document type: Journal article
Source: Astronomy & Astrophysics; v. 606, OCT 16 2017.
Web of Science Citations: 0

Context. Interacting galaxies surrounded by H-I tidal debris are ideal sites for the study of young clusters and tidal galaxy formation. The process that triggers star formation in the low-density environments outside galaxies is still an open question. New clusters and galaxies of tidal origin are expected to have high metallicities for their luminosities. Spectroscopy of such objects is, however, at the limit of what can be done with existing 8-10 m class telescopes, which has prevented statistical studies of these objects. Aims. NGC 2865 is a UV-bright merging elliptical galaxy with shells and extended H-I tails. In this work we aim to observe regions previously detected using multi-slit imaging spectroscopy. Methods. We obtained new multi-slit spectroscopy of six young star-forming regions around NGC 2865, to determine their redshifts and metallicities. Results. The six emission-line regions are located 16-40 kpc from NGC 2865 and they have similar redshifts. They have ages of similar to 10 Myr and an average metallicity of similar to 12 + log(O/H) similar to 8.6, suggesting a tidal origin for the regions. We note that they coincide with an extended H-I tail, which has projected density of N-III < 10(19) cm(-2), and displays a low surface brightness counterpart. These regions may represent the youngest of the three populations of star clusters already identified in NGC 2865. Conclusions. The high, nearly-solar, oxygen abundances found for the six regions in the vicinity of NGC 2865 suggest that they were formed by pre-enriched material from the parent galaxy, from gas removed during the most recent major merger. Given the mass and the location of the H-II regions, we can speculate that these young star-forming regions are potential precursors of globular clusters that will be part of the halo of NGC 2865 in the future. Our result supports the use of the multi-slit imaging spectroscopy as a useful tool for finding nearly-formed stellar systems around galaxies. (AU)

FAPESP's process: 09/54202-8 - Acquisition of a robotic telescope for the Brazilian astronomical community
Grantee:Claudia Lucia Mendes de Oliveira
Support type: Multi-user Equipment Program
FAPESP's process: 16/17119-9 - The study of galaxies in groups with SAM-FP and T80-south and the construction of the ABRAS T-100 telescope
Grantee:Claudia Lucia Mendes de Oliveira
Support type: Regular Research Grants