Infrared astronomy beyond JWST: the Moon perspective

In the first special issue on 'Astronomy from the Moon: the next decades', two projects for the infrared domain, considered as justifying a lunar implementation, were presented: a general purpose light collector for the 1-200 μm range, of diameter much larger than any ELT on Earth and a specialized instrument in the very far-infrared aiming at the detection of the weak CMB spectral distortions. Learning from the launch of JWST, to surpass it in spatial, spectral resolution, spectral coverage and sensitivity, the concept of a large infrared, lunar collector is revisited to be specified on a more realistic approach. The telescope is designed to fit in its stowed configuration into the fairing of a future cargo launcher, in order to be deployed on the Moon in robotic mode from a single launch. With these constraints, its diameter is limited to 13 m, i.e. just twice JWST. The choice of the potential sites is also better defined, by selecting the coldest lunar spots that could provide a passive cooling, on average colder than is obtained for JWST at L2. In conclusion, the advantages and the requirements for the development of such a facility on the Moon in the next decades are reviewed. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Origin of an orbiting star around the galactic supermassive black hole

The tremendous tidal force that is linked to the supermassive black hole (SMBH) at the center of our galaxy is expected to strongly subdue star formation in its vicinity. Stars within 1'' from the SMBH thus likely formed further from the SMBH and migrated to their current positions. In this study, spectroscopic observations of the star S0-6/S10, one of the closest (projected distance from the SMBH of ≈0''.3) late-type stars were conducted. Using metal absorption lines in the spectra of S0-6, the radial velocity of S0-6 from 2014 to 2021 was measured, and a marginal acceleration was detected, which indicated that S0-6 is close to the SMBH. The S0-6 spectra were employed to determine its stellar parameters including temperature, chemical abundances ([M/H], [Fe/H], [α/Fe], [Ca/Fe], [Mg/Fe], [Ti/Fe]), and age. As suggested by the results of this study, S0-6 is very old (≳10 Gyr) and has an origin different from that of stars born in the central pc region.

A half century of infrared astronomy - A personal recollection of the footprints in Japan

Since the new era of infrared astronomy was opened by the Two Micron Sky Survey by Neugebauer et al. in the early 1960s, about a half century has passed. During this time, observations have expanded rapidly and widely, to almost every field of astronomy, to reveal new perspectives on the universe. As a result, infrared astronomy has become one of the major branches of astronomy, along with optical, radio, X-ray as well as high-energy particle astronomy. In Japan, we started our infrared astronomical activities at a rather early time, under relatively poor technical and environmental conditions, and using somewhat unconventional methods to overcome these difficulties. Here, a brief survey is presented of developments concerning infrared astronomy during the past half century, while mainly recollecting our footprints in the stream of world activities.