We report the discovery of additional hot and massive stars in the cluster surrounding the soft gamma repeater SGR 1806−20, based upon UKIRT and Keck near-infrared spectroscopy. Of the newly identified stars, three are Wolf-Rayet stars of types WC8, WN6, and WN7, and a fourth star is an OB supergiant. These three stars, along with four previously discovered, imply a cluster age of∼3.04.5 Myr, b...

We present Hand K-band spectroscopy of OB and Wolf-Rayet (WR) members of the Milky Way cluster 1806–20 (G10.0–0.3), to obtain a revised cluster distance of relevance to the 2004 giant flare from the SGR 1806–20 magnetar. From GNIRS spectroscopy obtained with Gemini South, four candidate OB stars are confirmed as late O/early B supergiants, while we support previous mid WN and late WC classifica...

We report the results of radio flux-monitoring and high resolution observations at 3.6 cm with the VLA, of the central condensation in G 10.0−0.3, the radio nebula surrounding the soft gamma ray repeater (SGR) 1806−20. The quiescent X–ray source AX 1805.7−2025 is coincident with the radio core suggesting that G 10.0−0.3 is a plerionic supernova remnant. The monitoring experiment was performed i...

We present new millimeter and infrared spectroscopic observations towards the radio nebula G10.0−0.3, which is powered by the wind of the Luminous Blue Variable star LBV 1806−20 also closely associated with the soft gamma-ray repeater SGR 1806−20, and believed to be located in the giant Galactic H ii complex W31. Based on observations of CO emission lines and NH3 absorption features from molecu...

On 2004 Dec. 27, a giant γ-ray flare was detected from the magnetar SGR 1806–20. A radio observation seven days later revealed an expanding radio nebula at this position. Here we present results from an on-going monitoring campaign of this source with the Australia Telescope Compact Array and Very Large Array. These data indicate that there was an increase in the observed flux ∼25 days after th...

Claude Nicolas Ledoux (1736-1806) fue un arquitecto que trabajó con gran éxito para la aristocracia francesa en los años anteriores a Revolución.