Magnetic Fields and Fragmentation of Filaments in the Hub of California-X
We present 850 μ m polarization and C ^18 O (3-2) molecular line observations toward the X-shaped nebula in the California molecular cloud using James Clerk Maxwell Telescope (JCMT)’s SCUBA-2/POL-2 and HARP instruments. The 850 μ m emission shows that the observed region includes two elongated filam...
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| Format: | Article |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acd540 |
| _version_ | 1797255752132329472 |
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| author | Eun Jung Chung Chang Won Lee Woojin Kwon Mario Tafalla Shinyoung Kim Archana Soam Jungyeon Cho |
| author_facet | Eun Jung Chung Chang Won Lee Woojin Kwon Mario Tafalla Shinyoung Kim Archana Soam Jungyeon Cho |
| author_sort | Eun Jung Chung |
| collection | DOAJ |
| description | We present 850 μ m polarization and C ^18 O (3-2) molecular line observations toward the X-shaped nebula in the California molecular cloud using James Clerk Maxwell Telescope (JCMT)’s SCUBA-2/POL-2 and HARP instruments. The 850 μ m emission shows that the observed region includes two elongated filamentary structures (Fil1 and Fil2) having chains of regularly spaced cores. We measured the mass per unit length of the filaments and found that Fil1 and Fil2 are thermally super- and subcritical, respectively, but both are subcritical if nonthermal turbulence is considered. The mean projected spacings ( ${\rm{\Delta }}\bar{S}$ ) of the cores in Fil1 and Fil2 are 0.13 and 0.16 pc, respectively. ${\rm{\Delta }}\bar{S}$ is smaller than 4× the filament width expected in the classical cylinder fragmentation model. The large-scale magnetic field orientations shown by Planck are perpendicular to the long axes of Fil1 and Fil2, while those in the filaments obtained from the high-resolution polarization data of JCMT are disturbed, but those in Fil1 tend to have longitudinal orientations. Using the modified Davis–Chandrasekhar–Fermi method, we estimated the magnetic field strengths ( B _pos ) of the filaments, which are 110 ± 80 and 90 ± 60 μ G, respectively. We calculated the gravitational, kinematic, and magnetic energies of the filaments, and found that the fraction of magnetic energy is larger than 60% in both filaments. We propose that the dominant magnetic energy may lead the filament to be fragmented into aligned cores as suggested by Tang et al., and the shorter core spacing can be due to a projection effect via the inclined geometry of the filaments or due to nonnegligible longitudinal magnetic fields in the case of Fil1. |
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| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-24T22:10:50Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-d4ff75f374e642f285a6d51a5a2e79092024-03-20T09:51:55ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195116810.3847/1538-4357/acd540Magnetic Fields and Fragmentation of Filaments in the Hub of California-XEun Jung Chung0https://orcid.org/0000-0003-0014-1527Chang Won Lee1https://orcid.org/0000-0002-3179-6334Woojin Kwon2https://orcid.org/0000-0003-4022-4132Mario Tafalla3https://orcid.org/0000-0002-2569-1253Shinyoung Kim4https://orcid.org/0000-0001-9333-5608Archana Soam5https://orcid.org/0000-0002-6386-2906Jungyeon Cho6https://orcid.org/0000-0003-1725-4376Department of Astronomy and Space Science, Chungnam National University , Daejeon, Republic of Korea ; rigelej@gmail.comKorea Astronomy and Space Science Institute , 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea; University of Science and Technology , Korea (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of KoreaDepartment of Earth Science Education, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea; SNU Astronomy Research Center, Seoul National University , 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of KoreaObservatorio Astronómico Nacional (IGN) , Alfonso XII 3, E-28014 Madrid, SpainKorea Astronomy and Space Science Institute , 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of KoreaIndian Institute of Astrophysics , II Block, Koramangala, Bengaluru 560034, IndiaDepartment of Astronomy and Space Science, Chungnam National University , Daejeon, Republic of Korea ; rigelej@gmail.comWe present 850 μ m polarization and C ^18 O (3-2) molecular line observations toward the X-shaped nebula in the California molecular cloud using James Clerk Maxwell Telescope (JCMT)’s SCUBA-2/POL-2 and HARP instruments. The 850 μ m emission shows that the observed region includes two elongated filamentary structures (Fil1 and Fil2) having chains of regularly spaced cores. We measured the mass per unit length of the filaments and found that Fil1 and Fil2 are thermally super- and subcritical, respectively, but both are subcritical if nonthermal turbulence is considered. The mean projected spacings ( ${\rm{\Delta }}\bar{S}$ ) of the cores in Fil1 and Fil2 are 0.13 and 0.16 pc, respectively. ${\rm{\Delta }}\bar{S}$ is smaller than 4× the filament width expected in the classical cylinder fragmentation model. The large-scale magnetic field orientations shown by Planck are perpendicular to the long axes of Fil1 and Fil2, while those in the filaments obtained from the high-resolution polarization data of JCMT are disturbed, but those in Fil1 tend to have longitudinal orientations. Using the modified Davis–Chandrasekhar–Fermi method, we estimated the magnetic field strengths ( B _pos ) of the filaments, which are 110 ± 80 and 90 ± 60 μ G, respectively. We calculated the gravitational, kinematic, and magnetic energies of the filaments, and found that the fraction of magnetic energy is larger than 60% in both filaments. We propose that the dominant magnetic energy may lead the filament to be fragmented into aligned cores as suggested by Tang et al., and the shorter core spacing can be due to a projection effect via the inclined geometry of the filaments or due to nonnegligible longitudinal magnetic fields in the case of Fil1.https://doi.org/10.3847/1538-4357/acd540Interstellar magnetic fieldsInterstellar mediumPolarimetrySubmillimeter astronomyStar forming regions |
| spellingShingle | Eun Jung Chung Chang Won Lee Woojin Kwon Mario Tafalla Shinyoung Kim Archana Soam Jungyeon Cho Magnetic Fields and Fragmentation of Filaments in the Hub of California-X The Astrophysical Journal Interstellar magnetic fields Interstellar medium Polarimetry Submillimeter astronomy Star forming regions |
| title | Magnetic Fields and Fragmentation of Filaments in the Hub of California-X |
| title_full | Magnetic Fields and Fragmentation of Filaments in the Hub of California-X |
| title_fullStr | Magnetic Fields and Fragmentation of Filaments in the Hub of California-X |
| title_full_unstemmed | Magnetic Fields and Fragmentation of Filaments in the Hub of California-X |
| title_short | Magnetic Fields and Fragmentation of Filaments in the Hub of California-X |
| title_sort | magnetic fields and fragmentation of filaments in the hub of california x |
| topic | Interstellar magnetic fields Interstellar medium Polarimetry Submillimeter astronomy Star forming regions |
| url | https://doi.org/10.3847/1538-4357/acd540 |
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