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Near-Infrared Spectroscopy of the Blue Compact Dwarf Galaxy Markarian 59
We present near-infrared (NIR) spectroscopic observations of the bluecompact dwarf (BCD) galaxy Markarian 59 (Mrk 59), obtained with theTripleSpec spectrograph mounted on the 3.5 m Apache Point Observatorytelescope. The NIR spectrum of Mrk 59, which covers the 0.90 ?m-2.40?m wavelength range, shows atomic hydrogen, molecular hydrogen,helium, sulfur, and iron emission lines. The NIR data have beensupplemented by a Sloan Digital Sky Survey optical spectrum. We foundextinction in the BCD to be low (A(V) = 0.24 mag) and to be the same inboth the optical and NIR ranges. The NIR light does not reveal hiddenstar formation. The H2 emission comes from dense clumps andthe H2 vibrational emission-line intensities can be accountedfor by photon excitation. No shock excitation is needed. A CLOUDYphotoionization model of Mrk 59 reproduces well the observed optical andNIR emission-line fluxes. There is no need to invoke sources ofionization other than stellar radiation. The [Fe II] 1.257 and1.643 ?m emission lines, often used as supernova shock indicators inlow-excitation high-metallicity starburst galaxies, cannot play such arole in high-excitation low-metallicity H II regions such as Mrk59.
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