Physical Sciences and Mathematics | Open Access Articles

Is Ngc 300 A Pure Exponential Disk Galaxy?, In Sung Jang, Roelof S. De Jong, Ivan Minchev, Eric F. Bell, Antonela Monachesi, Benne W. Holwerda, Jeremy Bailin, Adam Smercina, Richard D'Souza

Faculty Scholarship

NGC 300 is a low-mass disk galaxy in the Sculptor group. In the literature, it has been identified as a pure exponential disk galaxy, as its luminosity profile can be well fit with a single exponential law over many disk scale lengths (Type I). We investigate the stellar luminosity distribution of NGC 300 using Hubble Space Telescope archive data, reaching farther and deeper than any other previous studies. Color-magnitude diagrams show a significant population of old red giant branch (RGB) stars in all fields out to R ∼ 19 kpc (32′), as well as younger populations in the inner regions. …

Go to article

Galaxy And Mass Assembly (Gama): Defining Passive Galaxy Samples And Searching For The Uv Upturn, S. Phillipps, S. S. Ali, M. N. Bremer, R. De Propris, A. E. Sansom, M. E. Cluver, M. Alpaslan, S. Brough, M. J.I. Brown, L. J.M. Davies, S. P. Driver, M. W. Grootes, Benne W. Holwerda, A. M. Hopkins, P. A. James, K. Pimbblet, A. S.G. Robotham, E. N. Taylor, L. Wang

Faculty Scholarship

We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes internal to individual galaxies with no measurable influence from the galaxies' larger environment. We first define a clean sample of passive galaxies without a significant contribution to their UV flux from low-level star formation. We confirm that galaxies with the optical colours of red sequence galaxies often have signs of residual star formation, which, without other information, would prevent a convincing demonstration of …

Go to article

Galaxy And Mass Assembly (Gama): Properties And Evolution Of Red Spiral Galaxies, Smriti Mahajan, Kriti Kamal Gupta, Rahul Rana, M. J.I. Brown, S. Phillipps, Joss Bland-Hawthorn, M. N. Bremer, S. Brough, Benne W. Holwerda, A. M. Hopkins, J. Loveday, Kevin Pimbblet, Lingyu Wang

Faculty Scholarship

We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) survey to explore the cause of red optical colours in nearby (0.002 < z < 0.06) spiral galaxies. We show that the colours of red spiral galaxies are a direct consequence of some environment-related mechanism(s) that has removed dust and gas, leading to a lower star formation rate. We conclude that this process acts on long time-scales (several Gyr) due to a lack of morphological transformation associated with the transition in optical colour. The specific star formation rate (sSFR) and dust-to-stellar mass ratio of red spiral galaxies is found to be statistically lower than blue spiral galaxies. On the other hand, red spirals are on average 0.9 dex more massive, and reside in environments 2.6 times denser than their blue counterparts. We find no evidence of excessive nuclear activity, or higher inclination angles to support these as the major causes for the red optical colours seen in ≳47 per cent of all spirals in our sample. Furthermore, for a small subsample of our spiral galaxies that are detected in H I, we find that the SFR of gas-rich red spiral galaxies is lower by ∼1 dex than their blue counterparts.

Go to article

Physical Sciences and Mathematics Commons^™

Full-Text Articles in Physical Sciences and Mathematics

Is Ngc 300 A Pure Exponential Disk Galaxy?, In Sung Jang, Roelof S. De Jong, Ivan Minchev, Eric F. Bell, Antonela Monachesi, Benne W. Holwerda, Jeremy Bailin, Adam Smercina, Richard D'Souza

Faculty Scholarship

Faculty Scholarship

Galaxy And Mass Assembly (Gama): Properties And Evolution Of Red Spiral Galaxies, Smriti Mahajan, Kriti Kamal Gupta, Rahul Rana, M. J.I. Brown, S. Phillipps, Joss Bland-Hawthorn, M. N. Bremer, S. Brough, Benne W. Holwerda, A. M. Hopkins, J. Loveday, Kevin Pimbblet, Lingyu Wang

Faculty Scholarship