Download Studying the Metallicities of Dwarf Galaxies Myles McKay (SCSU)

Studying the Metallicities
of
Dwarf Galaxies
Myles McKay (SCSU)
Sabrina Stierwalt (NRAO)
Kartik Sheth (NRAO)
What is a Dwarf?
NO DEFINITION!
Milky Way Galaxy
NGC4413
10^11 M*
10^8 M* or less
.
Why study dwarf galaxies?
• Most numerous extragalactic population in the local
universe
• Maybe the building blocks of more massive galaxies
• Dwarf galaxies may be analogs to gas-rich galaxies
at high redshift.
• Insufficient star formation(some)
GALEX
SDSS
NUV/FUV
OPTICAL
.
S4G
INFARED
.
NGC4393
What affects the development?
•
HI
Open box Scenario
Closed box Scenario
External
Internal
•
•
Inflow of HI gas.
HI
METALS
Supernovae driven winds
Ram-pressure stripping
METALS
SUPERNOVAE
HI
HI
METALS
METALS
Metallicity
• Metallicity (Z)- The proportion of its matter made up of
chemical elements other than H and He.
• Using Palomar data to measure the metallicity.
Stellar-to-HI Mass Ratio (M*/M(HI)
• Spitzer (S⁴G)
(Kartik Sheth)
• Galaxies that have
lowest stellar mass
• Lowest stellar/HI
mass
• 19 galaxy sample
Stellar Mass(M*M(sun))
.
Sabrina Stierwalt
BACKGROUN
H alpha
SII
• Made metallicity
measurements
• Used IRAF to
reduce data
• Measure the
Halpha, OIII, and
SII.
SPATIAL AXIS
Palomar Double Spectrograph
COSMICRAYS
CONTIUUM
.
WAVELENGTH
PROCESS
Battle with IRAF
Fight with IDL
METALLICITY
BEAUTIFUL PLOT
Metalicity ranges
My Galaxies
Favors open box scenario
Other Galaxies
ABSOLUTE MAGNITUDE
Future Work
• Locate these galaxies
• Study their surroundings
• Compare their environments
Conclusion
Low mass dwarf galaxies that have insufficient star
formation are likely affected by their environment.
SUMMER
STUDENT
AND/OR
Acknowlegment
THANK YOU
National Radio Astronomy Observatory(NRAO)
National Science Foundation(NSF)
Mentors
National Astronomy Consortium (NAC) Cville Cohort
Questions?