The JCMT BISTRO Survey: The magnetised evolution of star-forming cores in the Ophiuchus Molecular Cloud interpreted using Histograms of Relative Orientation
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2024
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866908715211292672 |
|---|---|
| author | Perry, James P. Pattle, Kate Johnstone, Doug Kwon, Woojin Bourke, Tyler Chung, Eun Jung Coudé, Simon Doi, Yasuo Fanciullo, Lapo Hwang, Jihye Khan, Zacariyya A. Kwon, Jungmi Lai, Shih-Ping Gouellec, Valentin J. M. Le Lee, Chang Won Ohashi, Nagayoshi Sadavoy, Sarah Savini, Giorgio Sharma, Ekta Tamura, Motohide |
| author_facet | Perry, James P. Pattle, Kate Johnstone, Doug Kwon, Woojin Bourke, Tyler Chung, Eun Jung Coudé, Simon Doi, Yasuo Fanciullo, Lapo Hwang, Jihye Khan, Zacariyya A. Kwon, Jungmi Lai, Shih-Ping Gouellec, Valentin J. M. Le Lee, Chang Won Ohashi, Nagayoshi Sadavoy, Sarah Savini, Giorgio Sharma, Ekta Tamura, Motohide |
| contents | The relationship between B-field orientation and density structure in molecular clouds is often assessed using the Histogram of Relative Orientations (HRO). We perform a plane-of-the-sky geometrical analysis of projected B-fields, by interpreting HROs in dense, spheroidal, prestellar and protostellar cores. We use James Clerk Maxwell Telescope (JCMT) POL-2 850 $μ$m polarisation maps and Herschel column density maps to study dense cores in the Ophiuchus molecular cloud complex. We construct two-dimensional core models, assuming Plummer column density profiles and modelling both linear and hourglass B-fields. We find high-aspect-ratio ellipsoidal cores produce strong HRO signals, as measured using the shape parameter $ξ$. Cores with linear fields oriented $< 45^{\circ}$ from their minor axis produce constant HROs with $-1 < ξ< 0$, indicating fields are preferentially parallel to column density gradients. Fields parallel to the core minor axis produce the most negative value of $ξ$. For low-aspect-ratio cores, $ξ\approx 0$ for linear fields. Hourglass fields produce a minimum in $ξ$ at intermediate densities in all cases, converging to the minor-axis-parallel linear field value at high and low column densities. We create HROs for six dense cores in Ophiuchus. $ρ$ Oph A and IRAS 16293 have high aspect ratios and preferentially negative HROs, consistent with moderately strong-field behaviour. $ρ$ Oph C, L1689A and L1689B have low aspect ratios, and $ξ\approx 0$. $ρ$ Oph B is too complex to be modelled using a simple spheroidal field geometry. We see no signature of hourglass fields, agreeing with previous findings that dense cores generally exhibit linear fields on these size scales. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_17659 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The JCMT BISTRO Survey: The magnetised evolution of star-forming cores in the Ophiuchus Molecular Cloud interpreted using Histograms of Relative Orientation Perry, James P. Pattle, Kate Johnstone, Doug Kwon, Woojin Bourke, Tyler Chung, Eun Jung Coudé, Simon Doi, Yasuo Fanciullo, Lapo Hwang, Jihye Khan, Zacariyya A. Kwon, Jungmi Lai, Shih-Ping Gouellec, Valentin J. M. Le Lee, Chang Won Ohashi, Nagayoshi Sadavoy, Sarah Savini, Giorgio Sharma, Ekta Tamura, Motohide Astrophysics of Galaxies The relationship between B-field orientation and density structure in molecular clouds is often assessed using the Histogram of Relative Orientations (HRO). We perform a plane-of-the-sky geometrical analysis of projected B-fields, by interpreting HROs in dense, spheroidal, prestellar and protostellar cores. We use James Clerk Maxwell Telescope (JCMT) POL-2 850 $μ$m polarisation maps and Herschel column density maps to study dense cores in the Ophiuchus molecular cloud complex. We construct two-dimensional core models, assuming Plummer column density profiles and modelling both linear and hourglass B-fields. We find high-aspect-ratio ellipsoidal cores produce strong HRO signals, as measured using the shape parameter $ξ$. Cores with linear fields oriented $< 45^{\circ}$ from their minor axis produce constant HROs with $-1 < ξ< 0$, indicating fields are preferentially parallel to column density gradients. Fields parallel to the core minor axis produce the most negative value of $ξ$. For low-aspect-ratio cores, $ξ\approx 0$ for linear fields. Hourglass fields produce a minimum in $ξ$ at intermediate densities in all cases, converging to the minor-axis-parallel linear field value at high and low column densities. We create HROs for six dense cores in Ophiuchus. $ρ$ Oph A and IRAS 16293 have high aspect ratios and preferentially negative HROs, consistent with moderately strong-field behaviour. $ρ$ Oph C, L1689A and L1689B have low aspect ratios, and $ξ\approx 0$. $ρ$ Oph B is too complex to be modelled using a simple spheroidal field geometry. We see no signature of hourglass fields, agreeing with previous findings that dense cores generally exhibit linear fields on these size scales. |
| title | The JCMT BISTRO Survey: The magnetised evolution of star-forming cores in the Ophiuchus Molecular Cloud interpreted using Histograms of Relative Orientation |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2411.17659 |