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The Hidden Companion of VV114 (IC1623)

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Infrared Astronomy with Arrays

Part of the book series: Astrophysics and Space Science Library ((ASSL,volume 190))

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VV114 (IC1623) is a bright IRAS galaxy at a distance of 75 Mpc. This galaxy is characterized by a chaotic and knotty structure in the optical. We have obtained sub-arcsec (FWHM=0.5-0.8″) J, H and K images of this galaxy with MONICA (“Montreal Infrared Camera”) on the Canada-France-Hawaii telescope. Theses observations have unveiled two very strong infrared (IR) sources located ~15″ east of the main optical nucleus. These two sources, separated by 1.8″, are much brighter than the optical peak in the infrared. The JHK colors suggest that the brightest of the newly discovered IR sources is affected by at least 6 magnitudes of visual extinction. However, extinction alone cannot explain the observed colors and implies that a significant fraction (may be as large as 50%) of the K continuum is contributed by nebular (free-free) and hot-dust emission. The observed colors suggest that a large fraction of the structure seen in the western regions of the galaxy is due to the presence of several HII regions. The main centers of activity identified in VV114 are all spatially resolved. Therefore, an active galactic nuclei is unlikely to power the luminosity of this galaxy.

We have also secured medium resolution K-window spectra of the main IR sources of VV114. The observations were carried out on the United Kingdom Infrared Telescope using the long-slit, cool grating spectrometer CGS4. All sources show strong recombination lines of hydrogen and helium, several transitions of molecular hydrogen and deep CO bands at 2.3 μm. These spectral features are signatures of vigorous star formation activity (starburst). Both imaging and spectroscopic observations in the infrared clearly establish that VV114 is an interacting system involving at least two galaxies in which starburst activity is taking place. The possibility that VV114 is a multiple system involving more than two galaxies cannot be excluded with the present observations.

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  • Doyon, R., Nadeau, D., Joseph, R. D., Sanders, D. B., Goldader, J. D.,&Rowlands, N. 1993, in preparation.

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  • Scoville, N. Z., Sanders, D. B., Sargent, A. L, Soifer, B. T.,&Tinney, C. G.: 1989, Astrophysical Journal 345, L25

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© 1994 Springer Science+Business Media Dordrecht

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Doyon, R., Nadeau, D., Rowlands, N., Joseph, R.D., Sanders, D.B., Goldader, J.D. (1994). The Hidden Companion of VV114 (IC1623). In: McLean, I.S. (eds) Infrared Astronomy with Arrays. Astrophysics and Space Science Library, vol 190. Springer, Dordrecht.

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  • Print ISBN: 978-94-010-4466-0

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