A multi-wavelength analysis of NGC5161

Image credit: Carnegie-Irvine Galaxy Survey (CGS)

A quick look

Distance: ~25Mpc Roughly 20kpc (160”)

in radius, with an extended HI disk

Hubble type: Sc Disc with many arms Small central bulge

with no apparent bar

Why multi-wavelength?

Different wavelengths tell different stories!

HI: Velocity map

Measure rotation of galaxy

HI: Velocity dispersion

Low velocity dispersion

High velocity dispersion

Thick Disk?

Diagram from “Extra-planar Gas”, Oosterloo

HI => Star formation?

Does abundance of fuel translate to higher SFR, at least in the outer region?

How strong is the link, if there is one at all?

Ultraviolet

Near-ultraviolet (NUV), far-ultraviolet (FUV) Investigate flux ratio, giving us “color”

Raw UV images from GALEX

Ultraviolet

Near-ultraviolet (NUV), far-ultraviolet (FUV) Investigate flux ratio, giving us “color”

Raw UV images from GALEX

Star formation from FUV

FUV radiation: => Blue stars => Young stars => Recent star

formation!

Linear relationship:

Calzetti 2012, eqn 1.11 and table 1.12

Results (?)

Extinction

Dust absorbs and scatters short wavelength UV light

Longer wavelength infrared (IR) light re-emitted

“Reddening” “Attenuation” “Extinction”

=>

Calzetti 2012, eqn 1.11 and table 1.12

Star formation from IR + FUV

+ =

IR image (top left) from WISE

Total star formation: ~1 SM/yr

Comparing SFR and HI

SFR density scale length: 4.75kpcHI density scale length: 9.66kpc

Timescale for HI exhaustion: 4 Gyr

Stellar mass from NIR image

I-band (~700-900nm). Often considered as an optical band.

Formula from Bell+ 2003, table 7. Image from CGS.

Results

Scale length of disk profile: 3.90kpc Total stellar mass ~3x1010 SM

Summary

HI mass: 5x109 SM

Stellar mass: 3x1010 SM

SFR: 1 SM/yr

HI exhuastion in 4 Gyr

Scale lengths:

Stellar mass: 3.90 kpc

SFR: 4.75 kpc

HI: 9.67 kpc

NGC5161 is actively forming stars in both its bulge and arms.

Bulge SF is enhanced, but obscured by lots of dust.

Roughly Milky Way-sized galaxy, with classical exponential profiles.

Possible disk features such as warping.