Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined from<i>J</i> = 3–2 and<i>J</i> = 1–0 Transitions of CO

Minamidani, Tetsuhiro; Mizuno, N.; Mizuno, Yumiko; Kawamura, Akiko; Onishi, Toshikazu; Hasegawa, Tetsuo; Tatematsu, Ken’ichi; Ikeda, Masafumi; Moriguchi, Y.; Yamaguchi, Nobuyuki; Ott, J.; Wong, Tony; Müller, Erik; Pineda, J. L.; Hughes, Annie; Staveley‐Smith, L.; Klein, U.; Mizuno, Akira; Nikolić, S.; Booth, R. S.; Heikkilä, Arto; Nyman, L.-Å.; Lerner, M. S.; Garay, Guido; Kim, Sungeun; Fujishita, M.; Kawase, Tokuichi; Rubio, M.; Fukui, Y.

doi:10.1086/524038

Cited by 51 publications

(48 citation statements)

References 44 publications

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“…The eastern, western, and southern (Johansson et al 1998). Their physical properties adopted from Johansson et al (1998; see also recent studies of Minamidani et al 2008 andMizuno et al 2010) are listed in Table 10, including each GMC's local standard of rest velocity (V lsr ), CO line widths (ΔV ), virial mass (M vir ), luminosity mass (M lum ), and ratio of virial to luminosity mass. Note that M lum is converted from the CO luminosity L CO using M lum = 8.8 ± 5.6L CO M , revised from Equation (6) in Bolatto et al (2008) for an X CO value suitable for N 159 (Pineda et al 2009).…”

Section: Interstellar Environments and Star Formation Propertiesmentioning

confidence: 99%

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

Chen

Indebetouw

Chu

et al. 2010

ApJ

161

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The H ii complex N 159 in the Large Magellanic Cloud is used to study massive star formation in different environments, as it contains three giant molecular clouds (GMCs) that have similar sizes and masses but exhibit different intensities of star formation. We identify candidate massive young stellar objects (YSOs) using infrared photometry, and model their spectral energy distributions to constrain mass and evolutionary state. Good fits are obtained for less evolved Type I, I/II, and II sources. Our analysis suggests that there are massive embedded YSOs in N 159B, a maser source, and several ultracompact H ii regions. Massive O-type YSOs are found in GMCs N 159-E and N 159-W, which are associated with ionized gas, i.e., where massive stars formed a few Myr ago. The third GMC, N 159-S, has neither O-type YSOs nor evidence of previous massive star formation. This correlation between current and antecedent formation of massive stars suggests that energy feedback is relevant. We present evidence that N 159-W is forming YSOs spontaneously, while collapse in N 159-E may be triggered. Finally, we compare star formation rates determined from YSO counts with those from integrated Hα and 24 μm luminosities and expected from gas surface densities. Detailed dissection of extragalactic GMCs like the one presented here is key to revealing the physics underlying commonly used star formation scaling laws.

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Section: Interstellar Environments and Star Formation Propertiesmentioning

confidence: 99%

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

Chen

Indebetouw

Chu

et al. 2010

ApJ

161

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“…The present targets are chosen from the 32 molecular clumps identified by the 12 CO(J = 3-2) observations of the six GMCs in the LMC with the ASTE 10 m telescope at a spatial resolution of 5 pc (Minamidani et al 2008). The six GMCs were chosen from the NANTEN catalog of 12 CO(J = 1-0) GMCs compiled by Fukui et al (2008), and they comprised three Type III GMCs, two Type II GMCs, and one Type I GMC.…”

Section: Selection Of Molecular Clumpsmentioning

confidence: 99%

“…The observed clumps and their coordinates are listed in Table 1. Hereafter, the region names, which are in parentheses above or in Column 4 in Table 1, and the numbers of clumps, are used to identify the clumps, as in Minamidani et al (2008). Among nine molecular clumps, four are in the 30 Doradus region,30 Doradus No.…”

Section: Selection Of Molecular Clumpsmentioning

confidence: 99%

“…Most of these studies targeted extraordinary H ii regions so the sample is limited. Minamidani et al (2008) carried out 12 CO(J = 3-2) observations of six GMCs, including one Type I, two Type II, and three Type III GMCs, in the LMC with the ASTE 10 m telescope at a spatial resolution of 5 pc, and identified 32 molecular clumps. These data were combined with available 12 CO(J = 1-0) and 13 CO(J = 1-0) data and compared with large velocity gradient (LVG) calculations for 13 clumps.…”

Section: Introductionmentioning

confidence: 99%

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DENSE CLUMPS IN GIANT MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD: DENSITY AND TEMPERATURE DERIVED FROM¹³CO(J= 3-2) OBSERVATIONS

Minamidani

Tanaka

Mizuno

et al. 2011

The Astronomical Journal

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In order to precisely determine the temperature and density of molecular gas in the Large Magellanic Cloud, we made observations of the optically thin 13 CO(J = 3-2) transition using the ASTE 10 m telescope toward nine peaks where 12 CO(J = 3-2) clumps were previously detected with the same telescope. The molecular clumps include those in giant molecular cloud (GMC) Types I (with no signs of massive star formation), II (with H ii regions only), and III (with H ii regions and young star clusters). We detected 13 CO(J = 3-2) emission toward all the peaks and found that their intensities are 3-12 times lower than those of 12 CO(J = 3-2). We determined the intensity ratios of 12 CO(J = 3-2) to 13 CO(J = 3-2), R 12/13 3-2 , and 13 CO(J = 3-2) to 13 CO(J = 1-0), R 13 3-2/1-0 , at 45 resolution. These ratios were used in radiative transfer calculations in order to estimate the temperature and density of the clumps. The clumps have a kinetic temperature range of T kin = 15-200 K and a molecular hydrogen gas density range of n(H 2 ) = 8 × 10 2 -7 × 10 3 cm −3 . We confirmed that the higher density clumps have higher kinetic temperature and that the lower density clumps have lower kinetic temperature to better accuracy than in previous work. The kinetic temperature and density increase generally from a Type I GMC to a Type III GMC. We interpret that this difference reflects an evolutionary trend of star formation in molecular clumps. The R 13 3-2/1-0 and kinetic temperature of the clumps are well correlated with the Hα flux, suggesting that the heating of molecular gas with density n(H 2 ) = 10 3 -10 4 cm −3 can be explained by stellar far-ultravoilet photons.

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“…For the parameter space, we consider typical conditions in observed molecular clouds (Frerking et al 1987;Wilson et al 1997;Minamidani et al 2008;Crutcher et al 2010b;Burkhart et al 2015). These are a hydrogen number density of 9.1 cm −3 to 1.3 · 10 7 cm −3 , a gas temperature of 10 K to 300 K, a turbulent velocity of 100 m/s to 10 km/s, and a LOS magnetic field strength of 0.1 µG to 3100 µG.…”

Section: Approachmentioning

confidence: 99%

Magnetic fields in molecular clouds: Limitations of the analysis of Zeeman observations

Brauer

Wolf

Reißl

et al. 2017

A&A

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Context. Observations of Zeeman split spectral lines represent an important approach to derive the structure and strength of magnetic fields in molecular clouds. In contrast to the uncertainty of the spectral line observation itself, the uncertainty of the analysis method to derive the magnetic field strength from these observations is not been well characterized so far. Aims. We investigate the impact of several physical quantities on the uncertainty of the analysis method, which is used to derive the line-of-sight (LOS) magnetic field strength from Zeeman split spectral lines. These quantities are the density, temperature, velocity, and the magnetic field strength. Methods. We simulate the Zeeman splitting of the 1665 MHz OH line with the 3D radiative transfer (RT) extension ZRAD. This extension is based on the line RT code Mol3D (Ober et al. 2015) and has been developed for the POLArized RadIation Simulator POLARIS . Results. Observations of the OH Zeeman effect in typical molecular clouds are not significantly affected by the uncertainty of the analysis method. However, some observations obtained a magnetic field strength of more than ∼300 µG, which may result in an uncertainty of the analysis method of >10%. We derived an approximation to quantify the range of parameters in which the analysis method works sufficiently accurate and provide factors to convert our results to other spectral lines and species as well. We applied these conversion factors to CN and found that observations of the CN Zeeman effect in typical molecular clouds are neither significantly affected by the uncertainty of the analysis method. In addition, we found that the density has almost no impact on the uncertainty of the analysis method, unless it reaches values higher than those typically found in molecular clouds (n H 10 7 cm −3 ). Furthermore, the uncertainty of the analysis method increases, if both the gas velocity and the magnetic field show significant variations along the line-of-sight. However, this increase should be small in Zeeman observations of most molecular clouds considering typical velocities of ∼1 km/s.

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Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined fromJ = 3–2 andJ = 1–0 Transitions of CO

Cited by 51 publications

References 44 publications

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

DENSE CLUMPS IN GIANT MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD: DENSITY AND TEMPERATURE DERIVED FROM¹³CO(J= 3-2) OBSERVATIONS

Magnetic fields in molecular clouds: Limitations of the analysis of Zeeman observations

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Submillimeter Observations of Giant Molecular Clouds in the Large Magellanic Cloud: Temperature and Density as Determined fromJ = 3–2 andJ = 1–0 Transitions of CO

Cited by 51 publications

References 44 publications

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

SPITZERVIEW OF YOUNG MASSIVE STARS IN THE LARGE MAGELLANIC CLOUD H II COMPLEXES. II. N 159

DENSE CLUMPS IN GIANT MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD: DENSITY AND TEMPERATURE DERIVED FROM13CO(J= 3-2) OBSERVATIONS

Magnetic fields in molecular clouds: Limitations of the analysis of Zeeman observations

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DENSE CLUMPS IN GIANT MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD: DENSITY AND TEMPERATURE DERIVED FROM¹³CO(J= 3-2) OBSERVATIONS