ACA CO(J = 2–1) Mapping of the Nearest Spiral Galaxy M33. I. Initial Results and Identification of Molecular Clouds Konishi, Ayu Miura, Rie E. Triangulum Galaxy Local Group Molecular clouds Interstellar medium We thank the anonymous referee for their helpful comments, which significantly improved the manuscript. This paper makes use of the following ALMA data: [ADS/JAO.ALMA#2017.1.00461.S], [ADS/JAO.ALMA#2018.A.00058.S], [ADS/JAO.ALMA#2017.1.00901.S], and [ADS/JAO.ALMA#2019.1.01182.S]. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Data analysis was in part carried out on the Multi-wavelength Data Analysis System operated by the Astronomy Data Center (ADC), National Astronomical Observatory of Japan. K.M. was supported by the ALMA Japan Research Grant of NAOJ ALMA Project, NAOJ-ALMA-289. This work was supported by NAOJ ALMA Scientific Research grant Nos. 2022-22B and JSPS KAKENHI (grant Nos. JP18H05440, JP19H05075, JP21H00049, JP21H01136, and JP21K13962). We present the results of ALMA-ACA 7 m array observations in (CO)-C-12(J = 2-1), (CO)-C-13(J = 2-1), and (CO)-O-18(J = 2-1) line emission toward the molecular-gas disk in the Local Group spiral galaxy M33 at an angular resolution of 7.& DPRIME;31 x 6.& DPRIME;50 (30 x 26 pc). We combined the ACA 7 m array (CO)-C-12(J = 2-1) data with the IRAM 30 m data to compensate for emission from diffuse molecular-gas components. The ACA+IRAM combined (CO)-C-12(J = 2-1) map clearly depicts the cloud-scale molecular-gas structure over the M33 disk. Based on the ACA+IRAM (CO)-C-12(J = 2-1) cube data, we cataloged 848 molecular clouds with a mass range from 10(3)-10(6) M (& ODOT;). We found that high-mass clouds (& GE;10(5) M (& ODOT;)) tend to associate with the 8 & mu;m bright sources in the spiral arm region, while low-mass clouds (M (& ODOT;)) tend to be apart from such 8 & mu;m bright sources and to exist in the inter-arm region. We compared the cataloged clouds with GMCs observed by the IRAM 30 m telescope at 49 pc resolution (IRAM GMC), and found that a small IRAM GMC is likely to be identified as a single molecular cloud even in ACA+IRAM CO data, while a large IRAM GMC can be resolved into multiple ACA+IRAM clouds. The velocity dispersion of a large IRAM GMC is mainly dominated by the line-of-sight velocity difference between small clouds inside the GMC rather than the internal cloud velocity broadening. 2023-09-25T07:44:37Z 2023-09-25T07:44:37Z 2023-08-16 info:eu-repo/semantics/article Kazuyuki Muraoka et al 2023. ACA CO(J = 2–1) Mapping of the Nearest Spiral Galaxy M33. I. Initial Results and Identification of Molecular Clouds. ApJ 953 164. [DOI 10.3847/1538-4357/ace4bd] https://hdl.handle.net/10481/84608 10.3847/1538-4357/ace4bd eng http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Atribución 4.0 Internacional IOP