Spirality: A Novel Way to Measure Spiral Arm Pitch Angle
We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 min per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral image...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-10-01
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| Series: | Galaxies |
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| Online Access: | https://www.mdpi.com/2075-4434/10/5/100 |
| _version_ | 1797407240746958848 |
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| author | Deanna Shields Benjamin Boe Casey Pfountz Benjamin L. Davis Matthew Hartley Ryan Miller Zac Slade M. Shameer Abdeen Daniel Kennefick Julia Kennefick |
| author_facet | Deanna Shields Benjamin Boe Casey Pfountz Benjamin L. Davis Matthew Hartley Ryan Miller Zac Slade M. Shameer Abdeen Daniel Kennefick Julia Kennefick |
| author_sort | Deanna Shields |
| collection | DOAJ |
| description | We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 min per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code’s results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality’s error bars overlapped 2DFFT’s error bars for 26 of the 30 galaxies. The two methods’ agreement correlates strongly with galaxy radius in pixels and also with <i>i</i>-band magnitude, but not with redshift, a result that is consistent with at least some galaxies’ spiral structure being fully formed by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>z</mi><mo>=</mo><mn>1.2</mn></mrow></semantics></math></inline-formula>, beyond which there are few galaxies in our sample. The Spirality code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined. All code is freely available. |
| first_indexed | 2024-03-09T03:38:47Z |
| format | Article |
| id | doaj.art-c7d240ef2628481b9cd0f726d3c14c87 |
| institution | Directory Open Access Journal |
| issn | 2075-4434 |
| language | English |
| last_indexed | 2024-03-09T03:38:47Z |
| publishDate | 2022-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Galaxies |
| spelling | doaj.art-c7d240ef2628481b9cd0f726d3c14c872023-12-03T14:44:50ZengMDPI AGGalaxies2075-44342022-10-0110510010.3390/galaxies10050100Spirality: A Novel Way to Measure Spiral Arm Pitch AngleDeanna Shields0Benjamin Boe1Casey Pfountz2Benjamin L. Davis3Matthew Hartley4Ryan Miller5Zac Slade6M. Shameer Abdeen7Daniel Kennefick8Julia Kennefick9Department of Physics & Arkansas Center for Planetary Sciences, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701, USAInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USADepartment of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, 4070 Malott Hall, Lawrence, KS 66045-7582, USACenter for Astro, Particle and Planetary Physics (CAP<sup>3</sup>), New York University Abu Dhabi, Abu Dhabi 129188, United Arab EmiratesPhysics Department, California Institute of Technology, 103-33, Pasadena, CA 91125, USANASA Headquarters, 300 E. Street SW, Washington, DC 20546, USAFree Geek of Arkansas, 521 W Ash Street, Fayetteville, AR 72703, USADepartment of Physics and Astronomy, Georgia Southern University, Statesboro, GA 30458, USADepartment of Physics & Arkansas Center for Planetary Sciences, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701, USADepartment of Physics & Arkansas Center for Planetary Sciences, University of Arkansas, 226 Physics Building, 835 West Dickson Street, Fayetteville, AR 72701, USAWe present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 min per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code’s results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality’s error bars overlapped 2DFFT’s error bars for 26 of the 30 galaxies. The two methods’ agreement correlates strongly with galaxy radius in pixels and also with <i>i</i>-band magnitude, but not with redshift, a result that is consistent with at least some galaxies’ spiral structure being fully formed by <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>z</mi><mo>=</mo><mn>1.2</mn></mrow></semantics></math></inline-formula>, beyond which there are few galaxies in our sample. The Spirality code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined. All code is freely available.https://www.mdpi.com/2075-4434/10/5/100data analysis methodsimage analysis methodsgalaxiesspiral galaxiesspiral armsgalaxy structure |
| spellingShingle | Deanna Shields Benjamin Boe Casey Pfountz Benjamin L. Davis Matthew Hartley Ryan Miller Zac Slade M. Shameer Abdeen Daniel Kennefick Julia Kennefick Spirality: A Novel Way to Measure Spiral Arm Pitch Angle Galaxies data analysis methods image analysis methods galaxies spiral galaxies spiral arms galaxy structure |
| title | Spirality: A Novel Way to Measure Spiral Arm Pitch Angle |
| title_full | Spirality: A Novel Way to Measure Spiral Arm Pitch Angle |
| title_fullStr | Spirality: A Novel Way to Measure Spiral Arm Pitch Angle |
| title_full_unstemmed | Spirality: A Novel Way to Measure Spiral Arm Pitch Angle |
| title_short | Spirality: A Novel Way to Measure Spiral Arm Pitch Angle |
| title_sort | spirality a novel way to measure spiral arm pitch angle |
| topic | data analysis methods image analysis methods galaxies spiral galaxies spiral arms galaxy structure |
| url | https://www.mdpi.com/2075-4434/10/5/100 |
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