J-region asymptotic giant branch

The phrase J-region asymptotic giant branch (JAGB) refers to a recently-uncovered, promising standard candle consisting of a particular type of AGB star. The term J-region refers to a region of a color-magnitude diagram of J-K band to J band of AGB stars, which has the characteristic that the stars' J-magnitudes are consistent. (This region was discerned in a 2MASS-based study including AGB stars in the Large Magellanic Cloud). The stars consist of AGB carbon stars with a certain range of carbon abundance in their atmosphere. Within a particular J-K (J minus K color) magnitude range (1.3 to 2), their J-magnitude is consistent, allowing it to be used in estimating the distance to the star. An advantage of the JAGB method is that these stars are both bright and relatively easy to find. Furthermore, less observation is necessary to collect the necessary data. Because the passbands are in the infrared, JWST is suitable for carrying out the method, and its aperture, which is larger than that of HST, gives it angular resolution and light-collection advantages.