810 research outputs found
HOCO+ toward the Galactic Center
We have identified a weak thermal line U42.767, which has been detected only
in the directions toward Sgr A and Sgr B2, as the HOCO+ 2_{02}--1_{01}
transition. Because of the proximity of this line to the SiO maser line at
42.821 GHz (J=1-0 v=2),it was observable simultaneously in the ~43 GHz SiO
maser searches at Nobeyama. From the past data of SiO maser surveys of infrared
objects in the Galactic center, we created a map of emission distribution of
HOCO+ in the Sgr A molecular cloud as well as maps of the 29SiO J=1-0 v=0
thermal emission and H53alpha emission. The emission distribution of HOCO+ was
quite similar to the distribution of 29SiO emission. It suggests that the
enhancement of the HOCO+ abundance in the galactic center is induced by shock
activities which release the CO2 molecules frozen on grains into gases.Comment: PASJ Dec. 25, 2006 issue in pres
Millimeter Light Curve with Abrupt Jump in Cyg X-3 2008 April-May Outburst
Cyg X-3 is a well-known microquasar with a bipolar relativistic jet. Its
famous giant radio outbursts have been repeated once every several years.
However, the behavior of the millimeter wave emission has remained unclear
because of limitations of time resolution in previous observations. We report
here millimeter wave observations of Cyg X-3 experiencing giant outbursts with
one of the finest time resolutions. We find a series of short-lived flares with
amplitude of 1-2 Jy in the millimeter light curve of the 2008 April-May
outburst. They have flat spectra around 100 GHz. We also find abrupt and large
amplitude flux density changes with e-folding time of 3.6 minutes or less. The
source size of Cyg X-3 is constrained within 0.4 AU and the brightness
temperature is estimated to be K.Comment: 4 figures, PASJ, in pres
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