Astrophys. J., 790, 117 (2014/August-1)
Cannibalization and rebirth in the NGC 5387 system. I. The stellar stream and star-forming region.
BEATON R.L., MARTINEZ-DELGADO D., MAJEWSKI S.R., D'ONGHIA E., ZIBETTI S., GABANY R.J., JOHNSON K.E., BLANTON M. and VERBISCER A.
Abstract (from CDS):
We have identified a low surface brightness stellar stream from visual inspection of Sloan Digital Sky Survey (SDSS) imaging for the edge-on, spiral galaxy NGC 5387. An optically blue overdensity coincident with the stream intersection with the NGC 5387 disk was also identified in SDSS and in the Galaxy Evolution Explorer Deep Imaging Survey contributing 38% of the total far-UV integrated flux from NGC 5387. Deeper optical imaging was acquired with the Vatican Advanced Technology Telescope that confirmed the presence of both features. The stellar stream is red in color, (B - V) = 0.7, has a stellar mass of 6x108 M☉, which implies a 1:50 merger ratio, has a circular radius, Rcirc∼ 11.7 kpc, formed in ∼240 Myr, and the progenitor had a total mass of ∼4x1010 M☉. Spectroscopy from LBT+MODS1 was used to determine that the blue overdensity is at the same redshift as NGC 5387, consists of young stellar populations (∼10 Myr), is metal-poor (12 + log (O/H) = 8.03), and is forming stars at an enhanced rate (∼1-3 M☉/yr). The most likely interpretations are that the blue overdensity is (1) a region of enhanced star formation in the outer disk of NGC 5387 induced by the minor accretion event or (2) the progenitor of the stellar stream experiencing enhanced star formation. Additional exploration of these scenarios is presented in a companion paper.
galaxies: dwarf - galaxies: evolution - galaxies: general - galaxies: individual: NGC 5387 - galaxies: star formation
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