J/ApJ/911/81 H-band polarimetric obs. of the S235 complex (Devaraj+, 2021) ================================================================================ Magnetic fields and star formation around HII regions: the S235 complex. Devaraj R., Clemens D.P., Dewangan L.K., Luna A., Ray T.P., Mackey J. =2021ApJ...911...81D ================================================================================ ADC_Keywords: H II regions; Polarization; Photometry, infrared; Extinction; Stars, distances; Star Forming Region Keywords: H II regions ; Magnetic fields ; Interstellar magnetic fields ; Molecular clouds ; Starlight polarization ; Polarimetry Abstract: Magnetic fields are ubiquitous and essential in star formation. In particular, their role in regulating formation of stars across diverse environments like HII regions needs to be well understood. In this study, we present magnetic field properties toward the S235 complex using near-infrared (NIR) H-band polarimetric observations, obtained with the Mimir and POLICAN instruments. We selected 375 background stars in the field through combination of Gaia distances and extinctions from NIR colors. The plane-of-sky (POS) magnetic field orientations inferred from starlight polarization angles reveal a curved morphology tracing the spherical shell of the HII region. The large-scale magnetic field traced by Planck is parallel to the Galactic plane. We identified 11 dense clumps using 1.1mm dust emission, with masses between 33 and 525M_{sun}_. The clump-averaged POS magnetic field strengths were estimated to be between 36 and 121{mu}G, with a mean of ~65{mu}G. The mass-to-flux ratios for the clumps are found to be subcritical with turbulent Alfven Mach numbers less than 1, indicating a strongly magnetized region. The clumps show scaling of magnetic field strength versus density with a power-law index of 0.52+/-0.07, similar to ambipolar diffusion models. Our results indicate that the S235 complex is a region where stellar feedback triggers new stars, and the magnetic fields regulate the rate of new star formation. Description: NIR linear polarimetric observations were obtained in the H band (1.6um) using two instruments: Mimir and POLICAN. The Mimir instrument was located on the 1.8m Perkins telescope outside of Flagstaff, AZ. Observations with Mimir were carried out during 2015-January for seven nights. The POLICAN instrument operated on the 2.1m Guillermo Haro Astrophysical Observatory (OAGH) telescope in Cananea, Sonora, Mexico. Observations with the POLICAN instrument focused on reaching finer angular resolutions and signal-to-noise ratios for regions with high stellar density. Three subfields of 4x4arcmin^2^ were observed during 2017 September. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 87 623 Polarimetric properties of the 623 stars in the S235 complex table3.dat 136 375 Polarimetric and photometric properties of the 375 foreground-corrected embedded and background stars in the S235 complex -------------------------------------------------------------------------------- See also: VII/20 : Catalogue of HII Regions (Sharpless 1959) II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006) II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012) I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018) I/345 : Gaia DR2 (Gaia Collaboration, 2018) J/ApJ/649/759 : Bubbles in the galactic disk (Churchwell+, 2006) J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006) J/A+A/453/911 : VLA and IR observations of the S235A-B region (Felli+, 2006) J/ApJ/653/383 : SCUBA obs. in Orion A South region (Johnstone+, 2006) J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008) J/ApJ/721/137 : The Bolocam Galactic Plane Survey (BGPS) (Bally+, 2010) J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010) J/ApJ/741/21 : Polarization of stars in Taurus (Chapman+, 2011) J/MNRAS/414/1526 : Near-IR photometry of Sh 2-235 (Dewangan+, 2011) J/ApJ/741/110 : The BGPS. VII. Massive star-forming regions (Dunham+, 2011) J/A+A/530/A118 : G29.96-0.02 and G35.20-1.74 1mm and 3mm maps (Pillai+, 2011) J/ApJ/759/48 : YSOs in the Galactic HII region Sh2-297 (Mallick+, 2012) J/ApJS/208/14 : BGPS. IX. Data release 2. (Ginsburg+, 2013) J/A+A/569/L1 : Polarization hole in a starless core (Alves+, 2014) J/ApJ/793/126 : L204 - Cloud 3 polarimetry and photometry (Cashman+, 2014) J/MNRAS/439/3719 : Embedded clusters infrared photometry (Chavarria+, 2014) J/ApJ/783/1 : VRI and H polarization toward Sh 2-29 (Santos+, 2014) J/ApJ/838/80 : JHK polarimetry of stars behind bubble N4 (Chen+, 2017) J/ApJ/836/199 : IRDC G028.23-00.19 NIR polarimetry analysis (Hoq+, 2017) J/ApJ/849/157 : Polarimetry toward IC5146 background stars (Wang+, 2017) J/ApJ/867/79 : NIR obs. of GF 9/LDN 1082C field stars (Clemens+, 2018) J/ApJS/249/23 : Galactic Plane IR Polarization Survey, DR4 (Clemens+, 2020) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq [1/623] Star sequential identifier 5- 13 F9.6 deg RAdeg [85.1/85.41] Right Ascension (J2000) 15- 23 F9.6 deg DEdeg [35.6/35.95] Declination (J2000) 25- 30 F6.3 mag Hmag [9.18/16.06] Mimir or POLICAN H-band magnitude 32- 36 F5.3 mag e_Hmag [0/0.08] Uncertainty in Hmag 38- 42 F5.3 % Pol [0.2/9.75] debiased Polarization, percent 44- 48 F5.3 % e_Pol [0.078/3] Uncertainty in Pol 50- 55 F6.2 deg PA [1.1/179.8] Equatorial Position Angle 57- 61 F5.2 deg e_PA [0.97/32] Uncertainty in PA 63- 68 F6.3 % Q [-8.85/9.64] equatorial Stokes Q, percent 70- 74 F5.3 % e_Q [0.047/3.1] Uncertainty in Q 76- 81 F6.3 % U [-9.54/9.5] equatorial Stokes U, percent 83- 87 F5.3 % e_U [0.048/3] Uncertainty in U -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Unit s Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- Seq [1/375] Star sequential identifier (does not match Table 1) 5- 13 F9.6 deg RAdeg [85.1/85.41] Right Ascension (J2000) 15- 23 F9.6 deg DEdeg [35.6/35.95] Declination (J2000) 25- 28 F4.2 % Pol [0.04/9.71] Debiased Polarization, percent 30- 33 F4.2 % e_Pol [0.08/3] Uncertainty in Pol 35- 40 F6.2 deg PA [1/179] Equatorial Position Angle 42- 46 F5.2 deg e_PA [0.98/32] Uncertainty in PA 48- 52 F5.2 % Q [-9.03/9.44] Equatorial Stokes Q, percent 54- 57 F4.2 % e_Q [0.08/3.04] Uncertainty in Q 59- 63 F5.2 % U [-8.69/5.18] Equatorial Stokes U, percent 65- 68 F4.2 % e_U [0.08/3] Uncertainty in U 70- 75 F6.3 mag Jmag [10.58/20.14] 2MASS or UKIDSS J-band magnitude 77- 81 F5.3 mag e_Jmag [0.003/0.24] Uncertainty in Jmag 83- 88 F6.3 mag Hmag [10.11/16.95] 2MASS or UKIDSS H-band magnitude 90- 94 F5.3 mag e_Hmag [0.002/0.12] Uncertainty in Hmag 96-101 F6.3 mag Ksmag [9.82/15.53] 2MASS or UKIDSS Ks-band magnitude 103-107 F5.3 mag e_Ksmag [0.002/0.13] Uncertainty in Ksmag 109-113 F5.2 mag Av [-1.13/25.63] Visual extinction 115-118 F4.2 mag e_Av [0.03/3] Uncertainty in Av 120-124 F5.0 pc rest [1508/5496]?=0 Estimated distance from Bailer-Jones+ 2018, I/347 126-130 F5.0 pc b_rest [531/3732]?=0 Lower bound on rest 132-136 F5.0 pc B_rest [1750/7997]?=0 Upper bound on rest -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Oct-2022