Compact Radio Sources within 30" of Sgr A*: Proper Motions, Stellar Winds and the Accretion Rate onto Sgr A*

Abstract

Recent broad-band 34 and 44 GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR counterparts, as well as 44 proplyd candidates within 30" of Sgr A*. Radio observations obtained in 2011 and 2014 have been used to derive proper motions of eight young stars near Sgr A*. The accuracy of proper motion estimates based on near-IR observations by Lu et al. and Paumard et al. have been investigated by using their proper motions to predict the 2014 epoch positions of near-IR stars and comparing the predicted positions with those of radio counterparts in the 2014 radio observations. Predicted positions from Lu et al. show an rms scatter of 6 mas relative to the radio positions, while those from Paumard et al. show rms residuals of 20 mas, which is mainly due to uncertainties in the IR-based proper motions. Under the assumption of homogeneous ionized winds, we also determine the mass-loss rates of 11 radio stars, finding rates that are on average $\sim$2 times smaller than those determined from model atmosphere calculations and near-IR data. Clumpiness of ionized winds would reduce the mass loss rate of WR and O stars by additional factors of 3 and 10, respectively. One important implication of this is a reduction in the expected mass accretion rate onto Sgr A* from stellar winds by nearly an order of magnitude to a value of few$\times 10^{-7}$ \msol\ yr${}^{-1}$. Finally, we present the positions of 318 compact 34.5 GHz radio sources within 30\arcs\ of Sgr A*. At least 45 of these have stellar counterparts in the near-IR $K_s$ (2.18 $\mu$m) and $L^{\prime }$ (3.8$\mu$m) bands.

30 pages, 4 figures, ApJ (in press)

References in corpus (12)

• Physical Properties of Wolf-Rayet Stars
• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• Stellar and wind properties of massive stars in the central parsec of the Galaxy
• Galactic Centre stellar winds and Sgr A* accretion
• Variable accretion and emission from the stellar winds in the Galactic centre
• Detection of Galactic Center source G2 at 3.8 $\mu$m during periapse passage
• The Galactic Center cloud G2 and its gas streamer
• Radio Continuum Observations of the Galactic Center: Photoevaporative Proplyd-like Objects near Sgr A*
• Photometric Stellar Variability in the Galactic Center
• Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole
• M-Band Spectra of Dust Embedded Sources at the Galactic Center
• The Discovery of Radio Stars within 10 arcseconds of Sgr A* at 7mm

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