Ice Features of Low-luminosity Protostars in Near-infrared Spectra of AKARI/IRC

34 pages, 9 figuresInternational audienceAbstract We present near-infrared spectra of three low-luminosity protostars and one background star in the Perseus molecular cloud, acquired using the infrared camera on board the AKARI space telescope. For the comparison with different star-forming environments, we also present spectra of the massive protostar AFGL 7009S, where the protostellar envelope is heated significantly, and the low-mass protostar RNO 91, which is suspected to be undergoing an episodic burst. We detected ice absorption features of H 2 O, CO 2 , and CO in all spectra around the wavelengths of 3.05, 4.27, and 4.67 μ m, respectively. For at least two low-luminosity protostars, we also detected the XCN ice feature at 4.62 μ m. The presence of the crystalline H 2 O ice and XCN ice components indicates that the low-luminosity protostars experienced a hot phase via accretion bursts during the past mass accretion process. We compared the ice abundances of the low-luminosity protostars with those of embedded low-mass protostars and the dense molecular clouds and cores, suggesting that their ice abundances reflect the strength of prior bursts and the timescale after the last burst