Quantitative analysis of 3-arm spiral galaxies

A relatively small fraction of spiral galaxies has three spiral arms. It has been theorized that these "3-arm spirals" are relatively unstable and prone to decaying into even numbered patterns due to tidal interactions. We present a series of quantitative analyses on a large sample of 3-arm spiral galaxies selected by the Galaxy Zoo 2 group. Much of this analysis used the image processing interface known as the Spiral Arc Finder and Reporter (SpArcFiRe). This program traced spiral arms on submitted images of galaxies and provided information that allowed us to replicate the arms in another program like MS Excel. Most of our work involved images taken from the Sloan Digital Sky Survey (SDSS), supplemented with high-resolution Hubble Space Telescope (HST) observations. This allowed us to study the morphological demographics of our sample, for both the internal structure and arm symmetry. The HST images provided special insight into spiral structure and star formation for these galaxies. We analyzed the star formation in particular using the MIRA AL software for photometry. We also attempted in improve the signal-to-noise of our images using data from the Stripe 82 region of SDSS. Unexpectedly, 3-arm patterns coexist with strong central bars roughly as often as other spiral patterns. We also found that 3-arm spirals do not preferentially exist in low-density regions and may be triggered by interactions.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2019

Author dc:creator

• Hancock, Colin

Advisor dc:contributor.advisor

• Keel, William C.

Contributors dc:contributor

• Nair, Preethi
• Bailin, Jeremy
• Simmons, Brooke

• Astronomy
• Astrophysics
• Physics

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

u0015_0000001_0003372
Hancock_alatus_0004M_13911

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/6429