AKARI's infrared view on nearby stars : Using AKARI Infrared Camera All-Sky Survey, 2MASS, and Hipparcos catalog

TL;DR

This study utilizes AKARI infrared data combined with other catalogs to develop color-color and color-magnitude diagrams that effectively classify and analyze various types of stars and stellar objects, aiding future stellar evolution research.

Contribution

It introduces new infrared color diagrams for classifying stars and stellar objects, and demonstrates their effectiveness in identifying different object types and understanding stellar evolution.

Findings

Infrared color-color diagrams distinguish stars with circumstellar disks and envelopes.

Color-magnitude diagrams identify low-mass YSOs and AGB stars.

AKARI data is comparable to Spitzer data for stellar population analysis.

Abstract

Results: We found that the (B-V) v.s. (V-S9W) color-color diagram is useful to identify the stars with infrared excess emerged from circumstellar envelopes/disks. Be stars with infrared excess are well separated from other types of stars in this diagram. Whereas (J-L18W) v.s. (S9W-L18W) diagram is a powerful tool to classify several object-types. Carbon-rich asymptotic giant branch (AGB) stars and OH/IR stars form distinct sequences in this color-color diagram. Young stellar objects (YSOs), pre-main sequence (PMS) stars, post-AGB stars and planetary nebulae (PNe) have largest mid-infrared color-excess, and can be identified in infrared catalog. Finally, we plot L18W v.s. (S9W-L18W) color-magnitude diagram, using the AKARI data together with Hipparcos parallaxes. This diagram can be used to identify low-mass YSOs, as well as AGB stars. We found that this diagram is comparable to the [24] vs ([8.0]-[24]) diagram of Large Magellanic Cloud sources using the Spitzer Space Telescope data. Our understanding of Galactic objects will be used to interpret color-magnitude diagram of stellar populations in nearby galaxies which Spitzer Space Telescope has observed. Conclusions: Our study of the AKARI color-color and color-magnitude will be used to explore properties of unknown objects in future. In addition, our analysis highlights a future key project to understand stellar evolution with circumstellar envelope, once the forthcoming astronometrical data with GAIA are available.