SEARCHES FOR $\beta$-ALANINE AND PYRIMIDINE TOWARD ORION-KL

Abstract

Watanabe et al.}$ Ohio State University International Symposium on Molecular Spectroscopy, WH11 (2006).} have searched for $\alpha$-alanine in Ori-KL with the Nobeyama 45-m radio telescope. Blagojevic et al.} \textbf{339}, L7 (2003).} expected that $\beta$-alanine may have a larger abundance than $\alpha$-alanine in interstellar space. In meteorites the abundance ratio of glycine, $\beta$-alanine, $\alpha$-alanine is reported to be 1 : 2.35 : 0.26. Pyrimidine may be related to the nucleic acid base such as uracil and searched by Kuan et al.} \textbf{345}, 650 (2003).} In the present study, we carried out deep searches for $\beta$-alanine and pyrimidine toward Ori-KL by using a new waveguide-type sideband-separating receiver in the 3 mm band installed at Nobeyama 45-m telescope. Low noise characteristic of the receiver made it possible to high sensitive observation in wide freqency range. The rotational transitions of $\beta$-alanine and pyrimidine were not detected with upper limit abundances of 2.9$\times$10$^{14}$cm$^{-2}$, 8.8$\times$10$^{12}$cm$^{-2}$, respectivity. The upper limit for pyrimidine is an order of magnitude lower than the previous$^{\it{c}}$. Many un-identified lines have been detected and the carriers will be discussed.