We present the first results of the AKARI Infrared Camera near-infrared spectroscopic survey of the Large Magellanic Cloud (LMC). The circumstellar material of young stellar objects (YSOs) are affected by galactic environments such as a metallicity or radiation field. Ices control the chemical balance of circumstellar environments of embedded YSOs. We detected absorption features of the H2O ice 3.05 μm and the CO2 ice 4.27 μm stretching mode toward seven massive YSOs in the LMC. This is the first detection of the 4.27 μm CO2 ice feature toward extragalactic YSOs. The present samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45±0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17±0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.

We observed an area of 10 deg2 of the Large Magellanic Cloud using the Infrared Camera on board AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and 24 μm) and a dispersion prism (2 − 5 μm, λ/Δλ ~ 20) equipped in the IRC. The 11 and 15 μm data, which are unique to AKARI IRC, allow us to construct color-magnitude diagrams that are useful to identify stars with circumstellar dust. We found a new sequence in the color-magnitude diagram, which is attributed to red giants with luminosity fainter than that of the tip of the first red giant branch. We suggest that this sequence is likely to be related to the broad emission feature of aluminium oxide at 11.5 μm.

We cross-correlated the OGLE-II database with the SIRIUS JHK survey data in the Large Magellanic Cloud (LMC). After eliminating obvious spurious variables, we determined the pulsation periods for 9 681 stars by applying the Phase Dispersion Minimization (PDM) technique to the OGLE-II data. Based on these data, we studied the period-K magnitude (PK) relations of variable stars in the LMC and found a new sequence. Comparison between the theoretical pulsation model (Wood & Sebo 1996) and observational data suggests that the variable stars on the new sequence are Mira variables pulsating in the first overtone mode.

We found that the OGLE database contains most AGB stars associated with the SMC cluster NGC 419. Combining these data with our near-infrared (NIR) data, we obtained the following results: 1) Almost all AGB stars above the TRGB are variables. 2) Large amplitude variables tend to show more regular light curves. 3) Only the tip AGB stars (in this case, carbon stars) increase their amplitudes with their J – K colors and only the most evolved ones can become large amplitude (Mira-like) variables. 4) AGB variables may explain the sequences found by Wood et al. (1999).