emamajek on 05-Sep-2023 03:00:04 GMT about * g Sgr
HD 188899 (61 Sgr, GJ 773.1, GJ 9675, HR 7614, HIP 98258, Gaia DR3 6878130330567510144) has a new companion in the Gaia DR3 data (Gaia DR3 6878130334860128768) that appears to have not yet been listed in either the Washington Double Star catalog or SIMBAD as of Sept 2023. The pairing appears in Kervella+2022 (2022A&A...657A...7K , J/A+A/657/A7/tablea2)
61 Sgr A = 2MASS J19575703-1529293 = Gaia DR3 6878130330567510144 (G=4.814; GaiaDR3)
61 Sgr B = 2MASS J19575668-1529335 = Gaia DR3 6878130334860128768 (G=14.0057; GaiaDR3)
sep = 7.42"
PA = 232.01
(values from Kervella+2022)
During the 2MASS epoch (1999) the separation was 6.6" at PA=231deg.
Kervella+2022 estimates that the relative tangential motion between the pair is 2.08+-0.32 km/s while the escape velocity is predicted to be 2.98 km/s (hence at least the relative Gaia DR3 tangential motions are consistent with orbital motion).
The companion appears to have two TIC entries (TIC 48774608 for the 2MASS ID, TIC 1930496799 for the Gaia ID). The GaiaDR3 Part 3 (Non-Single Star) catalog gives an accelerated solution for A with parallax 13.4342300506006715+-0.1171690450mas.
Binarity was to be expected as the star was previously considered an 'unresolved Hipparcos problem star' (Mason+1999) and proper motion derivative binary (Makarov+2005,Frankowski+2007).
The GaiaDR3 parallax (13.43mas) and Gmag (G=14.00), and Bp-Rp color (1.801641) for the companion are consistent with absolute magnitudes (M_G ~ 9.65, M_Ks ~ 4.78) are consistent with either a late K or early M dwarf.
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