Galaxy Zoo:Unwinding the Winding Problem - Observations of Spiral Bulge Prominence and Arm Pitch Angles Suggest Local Spiral Galaxies are Winding

Masters, Karen L. and Lintott, Chris J. and Hart, Ross E. and Kruk, Sandor J. and Smethurst, Rebecca J. and Casteels, Kevin and Keel, William C. and Simmons, Brooke D. and Olivan Stanescu, Dennis and Tate, Jean and Tomi, Satoshi (2019) Galaxy Zoo:Unwinding the Winding Problem - Observations of Spiral Bulge Prominence and Arm Pitch Angles Suggest Local Spiral Galaxies are Winding. Monthly Notices of the Royal Astronomical Society. ISSN 0035-8711

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Abstract

We use classifications provided by citizen scientists though Galaxy Zoo to investigate the correlation between bulge size and arm winding in spiral galaxies. Whilst the traditional spiral sequence is based on a combination of both measures, and is supposed to favour arm winding where disagreement exists, we demonstrate that, in modern usage, the spiral classifications Sa-Sd are predominantly based on bulge size, with no reference to spiral arms. Furthermore, in a volume limited sample of galaxies with both automated and visual measures of bulge prominence and spiral arm tightness, there is at best a weak correlation between the two. Galaxies with small bulges have a wide range of arm winding, while those with larger bulges favour tighter arms. This observation, interpreted as revealing a variable winding speed as a function of bulge size, may be providing evidence that the majority of spiral arms are not static density waves, but rather wind-up over time. This suggests the "winding problem" could be solved by the constant reforming of spiral arms, rather than needing a static density wave. We further observe that galaxies exhibiting strong bars tend have more loosely wound arms at a given bulge size than unbarred spirals. This observations suggests that the presence of a bar may slow the winding speed of spirals, and may also drive other processes (such as density waves) which generate spiral arms. It is remarkable that after over 170 years of observations of spiral arms in galaxies our understanding of them remains incomplete....

Item Type:
Journal Article
Journal or Publication Title:
Monthly Notices of the Royal Astronomical Society
Additional Information:
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version Karen L Masters, Chris J Lintott, Ross E Hart, Sandor J Kruk, Rebecca J Smethurst, Kevin V Casteels, William C Keel, Brooke D Simmons, Dennis Olivan Stanescu, Jean Tate, Satoshi Tomi, Galaxy Zoo: Unwinding the Winding Problem – Observations of Spiral Bulge Prominence and Arm Pitch Angles Suggest Local Spiral Galaxies are Winding, Monthly Notices of the Royal Astronomical Society, , stz1153, https://doi.org/10.1093/mnras/stz1153 is available online at:
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1900/1912
Subjects:
ID Code:
133999
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Deposited On:
22 Jun 2019 09:14
Refereed?:
Yes
Published?:
Published
Last Modified:
22 Oct 2020 06:08