Download AKARI Infrared Camera (IRC) Spectroscopy Observations: Highlights

AKARI Infrared Camera (IRC) Imaging Observations: Highlights
Yoshifusa ITA1) and AKARI/IRC team
1) National Institutes of Natural Sciences, National Astronomical Observatory of Japan, 2-21-1
Osawa, Mitaka, Tokyo, 181-8588, Japan
[email protected]
The Infrared Camera (IRC; Onaka et al 2007) is one of the two main instruments on board the
AKARI (formerly ASTRO-F; Murakami et al. 2007) satellite. The IRC is comprised of three
independent arrays; NIR, MIRS, and MIRL, which cover the 1.8–5.5um, 4.6–13.4um, and
12.6–26.5 um wavelength range, respectively. Each of the three arrays has three imaging filters,
which can be switched during the observation. Each of the arrays has a wide field of view of
about 10’x10’, suitable for survey-type observations. Here we present some highlights of the
IRC imaging observations made so far, to demonstrate the ability of the IRC and its
performance.
1. Supernova remnant in the Small Magellanic Cloud: B0104-72.3, a well-known supernova
remnant in the SMC was imaged by the IRC at four different infrared wavelengths. The
intensity ratios of them revealed the presence of a shock at the interaction between the
expanding remnant and the surrounding molecular clouds. This implies that the precursor
was a high-mass star (Koo et al 2007).
2. Mass-loss from young red-giants in a globular cluster NGC 104: A globular cluster,
NGC104 was imaged by the IRC at 3, 4, 7, 11, 15, and 24 micrometers. The intensity ratio
vs. K magnitude diagram showed evidence of mass-loss from young red-giant stars. The
mass loss in the early red-giant phase, important for understanding the evolution of
galaxies, had been predicted only in theory so far. (Ita et al 2007)
3. Intense star formation activity in the early Universe: North Ecliptic Pole region was deeply
imaged by the IRC, resulting in the detection of around 280 galaxies, confirming the
increase in the number of galaxies at 15 micrometers implied by the earlier ISO
observations. Comparable numbers of even fainter galaxies have been discovered, leading
to the conclusion that the star formation activity was already intense even earlier than 6
thousand million years in the past. Similar deep surveys over the entire IRC wavelength
range are being carried out. These data will provide a definitive description of the
evolution of galaxies over the lifetime of the Universe (Matsuhara et al. 2007; Wada et al
2007).
4. Near- and mid-infrared view of the Large Magellanic Cloud: About 13 square degrees of
the main part of the LMC are surveyed by the IRC. The data will enable us to study the
way stars recycle their constituent gases and return them to the interstellar medium at the
end of their lives.
5. More to come!!
This paper is a mere summary of the web pages,
http://www.ir.isas.jaxa.jp/ASTRO-F/Outreach/results/results_e.html
and
http://akari.esac.esa.int/ .
Please visit the urls if you are interested.
References
Ita, Y., et al. 2007, PASJ, 59, 437
Koo, B.-C., et al. 2007, PASJ, 59, 455
Matsuhara, H., et al. 2007, PASJ, 59, 543
Murakami, H., et al. 2007, PASJ, 59, 369
Onaka, T., et al. 2007, PASJ, 59, 401
Wada, T., et al. 2007, PASJ, 59, 515