The Relative Orientation between Local Magnetic Field and Galactic Plane in Low Latitude Dark Clouds  

作　　者：Gulafsha B.Choudhury Himadri S.Das B.J.Medhi J.C.Pandey S.Wolf T.K.Dhar A.M.Mazarbhuiya 

机构地区：[1]Department of Physics,Assam University,Silchar 788011,India [2]Department of Physics,Gauhati University,Guwahati 781014,India [3]Aryabhatta Research Institute of Observational Sciences(ARIES),Nainital 263002,India [4]University of Kiel,Institute of Theoretical Physics and Astrophysics,Leibnizstrasse 15,D-24118,Kiel,Germany

出　　处：《Research in Astronomy and Astrophysics》2022年第7期84-98,共15页天文和天体物理学研究（英文版）

基　　金：funding agency Department of Science and Technology (DST), Government of India for providing the DST INSPIRE fellowship (IF 170830)。

摘　　要：In this work,we study the magnetic field morphology of selected star-forming clouds spread over the galactic latitude(b)range−10°to 10°.The polarimetric observations of clouds CB24,CB27 and CB188 are conducted to study the magnetic field geometry of those clouds using the 104 cm Sampurnanand Telescope(ST)located at ARIES,Manora Peak,Nainital,India.These observations are combined with those of 14 further low latitude clouds available in the literature.Most of these clouds are located within a distance range 140–500 pc except for CB3(∼2500 pc),CB34(∼1500 pc),CB39(∼1500 pc)and CB60(∼1500 pc).Analyzing the polarimetric data of 17 clouds,we find that the alignment between the envelope magnetic field(θ^(env)_(B))and galactic plane(GP)(θGP)of the low-latitude clouds varies with their galactic longitudes(l).We observe a strong correlation between the longitude(l)and the offset(θ_(off)=|θ^(env)_(B)-θ_(GP))which shows that θ^(env)_(B) is parallel to the GP when the clouds are situated in the region 115°<l<250°.However,θ^(env)_(B) has its own local deflection irrespective of the orientation of θGP when the clouds are at l<100°and l>250°.To check the consistency of our results,the stellar polarization data available in the Heiles catalog are overlaid on the DSS image of the clouds having mean polarization vector of field stars.The results are almost consistent with the Heiles data.A systematic discussion is presented in the paper.The effect of turbulence in the cloud is also studied which may play an important role in causing the misalignment phenomenon observed between θ^(env)_(B) and θ_(GP).We have used Herschel(Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.)SPIRE 500μm and SCUBA 850μm dust continuum emission maps in our work to understand the density structure of the clouds.

关 键 词：POLARIZATION (ISM:)dust EXTINCTION ISM:magnetic fields galaxies:magnetic fields 

分 类 号：P156[天文地球—天文学]