Stellar Systems Group

Yusef-Zadeh, F.; Roberts, D. A.; Wardle, M.; Cotton, W.; Schödel, R.; Royster, M. J.
The Astrophysical Journal Letters, Volume 801, Issue 2, article id. L26, 7 pp. (2015).
03/2015

ABSTRACT

We present radio images within 30″ of Sgr A* based on recent VLA observations at 34 GHz with 7.8 μJy sensitivity and resolution of ∼ 88× 46 mas. We report 44 partially resolved compact sources clustered in two regions in the E arm of ionized gas that orbits Sgr A*. These sources have size scales ranging between ∼50 and 200 mas (400–1600 AUs), and a bow- shock appearance facing the direction of Sgr A*. Unlike the bow-shock sources previously identified in the near-IR but associated with massive stars, these 34 GHz sources do not appear to have near-IR counterparts at 3.8 μm. We interpret these sources as a candidate population of photoevaporative protoplanetary disks (proplyds) that are associated with newly formed low mass stars with mass loss rates ∼ {{10}^-7}-{{10}^-6} {{M}_ȯ } yr^‑1 and are located at the edge of a molecular cloud outlined by ionized gas. The disks are externally illuminated by strong Lyman continuum radiation from the ∼100 OB and WR massive stars distributed within 10″ of Sgr A*. The presence of proplyds implies current in situ star formation activity near Sgr A* and opens a window for the first time to study low mass star, planetary, and brown dwarf formations near a supermassive black hole.