We report Shanghai Tian Ma Radio Telescope detections of several long carbonchain molecules at C and Ku band, including HC 3 N, HC 5 N, HC 7 N, HC 9 N, C 3 S, C 6 H and C 8 H toward the starless cloud Serpens South 1a. We detected some transitions (HC 9 N J=13-12 F=12-11 and F=14-13, H 13 CCCN J=2-1 F=1-0 and F=1-1, HC 13 CCN J=2-1 F=2-2, F=1-0 and F=1-1, HCC 13 CN J=2-1 F=1-0 and F=1-1) and resolved some hyperfine components (HC 5 N J=6-5 F=5-4, H 13 CCCN J=2-1 F=2-1) for the first time in the interstellar medium. The column densities of these carbon-chain molecules in a range of 10 12 -10 13 cm −2 are comparable to two carbon-chain molecule rich sources, TMC-1 and Lupus-1A. The abundance ratios are 1.00:(1.11±0.15):(1.47±0.18) for [H 13 CCCN]:[HC 13 CCN]:[HCC 13 CN]. This result implies that the 13 C isotope is also concentrated in the carbon atom adjacent to the nitrogen atom in HC 3 N in Serpens south 1a, which is similar to TMC-1. The [HC 3 N]/[H 13 CCCN] ratio of 78±9, the [HC 3 N]/[HC 13 CCN] ratio of 70±8, and the [HC 3 N]/[HCC 13 CN] ratio of 53±4 are also comparable to those in TMC-1. In any case, Serpens South 1a proves a testing ground for understanding carbon-chain chemistry.
We report the detection of widespread CH 2 OHCHO and HOCH 2 CH 2 OH emission in Galactic center giant molecular cloud Sagittarius B2 using the Shanghai Tianma 65m Radio Telescope. Our observations show for the first time that the spatial distribution of these two important prebiotic molecules extends over 15 arc-minutes, corresponding to a linear size of approximately 36 pc. These two molecules are not just distributed in or near the hot cores. The abundance of these two molecules seems to decrease from the cold outer region to the central region associated with star-formation activity. Results present here suggest that these two molecules are likely to form through a low temperature process. Recent theoretical and experimental studies demonstrated that prebiotic molecules can be efficiently formed in icy grain mantles through several pathways. However, these complex ice features cannot be directly observed, and most constraints on the ice compositions come from millimeter observations of desorbed ice chemistry products. These results, combined with laboratory studies, strongly support the existence of abundant prebiotic molecules in ices.
In this paper, we report radio observations of the Galactic Center magnetar PSR J1745−2900 at six epochs between June and October, 2014. These observations were carried out using the new Shanghai Tian Ma Radio Telescope at a frequency of 8.6 GHz. Both the flux density and integrated profile of PSR J1745−2900 show dramatic changes from epoch to epoch showing that the pulsar was in its "erratic" phase. On MJD 56836, the flux density of this magnetar was about 8.7 mJy, which was ten times large than that reported at the time of discovery, enabling a single-pulse analysis. The emission is dominated by narrow "spiky" pulses which follow a log-normal distribution in peak flux density. From 1913 pulses, we detected 53 pulses whose peak flux density is ten times greater than that of the integrated profile. They are concentrated in pulse phase at the peaks of the integrated profile. The pulse widths at the 50% level of these bright pulses was between 0.2 • to 0.9 • , much narrower than that of integrated profile (∼12 • ). The observed pulse widths may be limited by interstellar scattering. No clear correlation was found between the widths and peak flux density of these pulses and no evidence was found for subpulse drifting. Relatively strong spiky pulses are also detected in the other five epochs of
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