We have analyzed Atacama Large Millimeter/submillimeter Array Band 6 data of the hypercompact H i... more We have analyzed Atacama Large Millimeter/submillimeter Array Band 6 data of the hypercompact H ii region G24.78+0.08 A1 (G24 HC H ii) and report the detection of vibrationally excited lines of HC3N (v 7 = 2, J = 24 − 23). The spatial distribution and kinematics of a vibrationally excited line of HC3N (v 7 = 2, J = 24 − 23, l = 2e) are found to be similar to the CH3CN vibrationally excited line (v 8 = 1), which indicates that the HC3N emission is tracing the disk around the G24 HC H ii region previously identified by the CH3CN lines. We derive the 13CH3CN/HC13CCN abundance ratios around G24 and compare them to the CH3CN/HC3N abundance ratios in disks around Herbig Ae and T Tauri stars. The 13CH3CN/HC13CCN ratios around G24 (∼3.0–3.5) are higher than the CH3CN/HC3N ratios in the other disks (∼0.03–0.11) by more than 1 order of magnitude. The higher CH3CN/HC3N ratios around G24 suggest that the thermal desorption of CH3CN in the hot dense gas and efficient destruction of HC3N in the r...
We present the results of ALMA observations toward the low-mass Class 0 binary system VLA 1623Aab... more We present the results of ALMA observations toward the low-mass Class 0 binary system VLA 1623Aab in the Ophiuchus molecular cloud in 12CO, 13CO, and C18O(2–1) lines. Our 12CO (J = 2–1) data reveal that the VLA 1623 outflow consists of twin spatially overlapped outflows/jets. The redshifted northwestern jet exhibits three cycles of wiggle with a spatial period of 1360 ± 10 au, corresponding to a time period of 180 yr. The wiggle-like structure is also found in the position–velocity (PV) diagram, showing an amplitude in the velocity of about 0.9 km s−1. Both the period and velocity amplitude of the wiggle are roughly consistent with those expected from the binary parameters, i.e., the orbital period (460 ± 20 yr) and the Keplerian velocity (2.2 km s−1). Our 13CO and C18O images show a dense gas nature in the two centimeter/millimeter sources, VLA 1623B and W, and its relation to the outflows, and strongly support the previous interpretation that both are shocked cloudlets. The drivin...
Aims. HL Tau is a Class I–II protostar embedded in an infalling and rotating envelope and possibl... more Aims. HL Tau is a Class I–II protostar embedded in an infalling and rotating envelope and possibly associated with a planet forming disk, and it is co-located in a 0.1 pc molecular cloud with two nearby young stellar objects with projected distance of ~20′′–30′′ (2800–4200 au) to HL Tau. Our observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) revealed two arc-like structures on a 1000 au scale connected to the disk, and their kinematics could not be explained with any conventional model of infalling and rotational motions. In this work, we investigate the nature of these arc-like structures connected to the HL Tau disk. Methods. We carried out new observations in the 13CO and C18O (3–2; 2–1) lines with the James Clerk Maxwell Telescope and the IRAM 30m telescope, and obtained the data with the 7-m array of the Atacama Compact Array (ACA). With the single-dish, ACA, and ALMA data, we analyzed the gas motions on both 0.1 pc and 1000 au scales in the HL Tau region...
We have analyzed Atacama Large Millimeter/submillimeter Array Band 6 data of the hypercompact H i... more We have analyzed Atacama Large Millimeter/submillimeter Array Band 6 data of the hypercompact H ii region G24.78+0.08 A1 (G24 HC H ii) and report the detection of vibrationally excited lines of HC3N (v 7 = 2, J = 24 − 23). The spatial distribution and kinematics of a vibrationally excited line of HC3N (v 7 = 2, J = 24 − 23, l = 2e) are found to be similar to the CH3CN vibrationally excited line (v 8 = 1), which indicates that the HC3N emission is tracing the disk around the G24 HC H ii region previously identified by the CH3CN lines. We derive the 13CH3CN/HC13CCN abundance ratios around G24 and compare them to the CH3CN/HC3N abundance ratios in disks around Herbig Ae and T Tauri stars. The 13CH3CN/HC13CCN ratios around G24 (∼3.0–3.5) are higher than the CH3CN/HC3N ratios in the other disks (∼0.03–0.11) by more than 1 order of magnitude. The higher CH3CN/HC3N ratios around G24 suggest that the thermal desorption of CH3CN in the hot dense gas and efficient destruction of HC3N in the r...
We present the results of ALMA observations toward the low-mass Class 0 binary system VLA 1623Aab... more We present the results of ALMA observations toward the low-mass Class 0 binary system VLA 1623Aab in the Ophiuchus molecular cloud in 12CO, 13CO, and C18O(2–1) lines. Our 12CO (J = 2–1) data reveal that the VLA 1623 outflow consists of twin spatially overlapped outflows/jets. The redshifted northwestern jet exhibits three cycles of wiggle with a spatial period of 1360 ± 10 au, corresponding to a time period of 180 yr. The wiggle-like structure is also found in the position–velocity (PV) diagram, showing an amplitude in the velocity of about 0.9 km s−1. Both the period and velocity amplitude of the wiggle are roughly consistent with those expected from the binary parameters, i.e., the orbital period (460 ± 20 yr) and the Keplerian velocity (2.2 km s−1). Our 13CO and C18O images show a dense gas nature in the two centimeter/millimeter sources, VLA 1623B and W, and its relation to the outflows, and strongly support the previous interpretation that both are shocked cloudlets. The drivin...
Aims. HL Tau is a Class I–II protostar embedded in an infalling and rotating envelope and possibl... more Aims. HL Tau is a Class I–II protostar embedded in an infalling and rotating envelope and possibly associated with a planet forming disk, and it is co-located in a 0.1 pc molecular cloud with two nearby young stellar objects with projected distance of ~20′′–30′′ (2800–4200 au) to HL Tau. Our observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) revealed two arc-like structures on a 1000 au scale connected to the disk, and their kinematics could not be explained with any conventional model of infalling and rotational motions. In this work, we investigate the nature of these arc-like structures connected to the HL Tau disk. Methods. We carried out new observations in the 13CO and C18O (3–2; 2–1) lines with the James Clerk Maxwell Telescope and the IRAM 30m telescope, and obtained the data with the 7-m array of the Atacama Compact Array (ACA). With the single-dish, ACA, and ALMA data, we analyzed the gas motions on both 0.1 pc and 1000 au scales in the HL Tau region...
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