NGC 4330 Recap & LateStage Addi6ons to Paper Anne Abramson - PowerPoint PPT Presentation

NGC 4330 Recap & Late‐Stage Addi6ons to Paper Anne Abramson June 16, 2010

Paper Recap • Morphological Features • Derived Evolu6onary Timescales • Stripping History

Morphological Tracers of RPS • ISM trunca6on along major axis • Extraplanar HI • UV major axis asymmetry • The Upturn • The Tail • Extraplanar UV Regions

Morphological Tracers of RPS • ISM trunca6on along major axis HI, dust ex6nc6on stripped to well within undisturbed old stellar disk (50 – 65% of R_25)

Morphological Tracers of RPS • One‐sided extraplanar HI – 32% total downwind, 10% in tail

Morphological Tracers of RPS • UV major axis asymmetry Recent SF highly truncated on leading side, less so on trailing side; ongoing SF symmetric about center Indicates change in spa6al distribu6on of SF regions within last ~10 Myr

Morphological Tracers of RPS • The Upturn – striking, hitherto undocumented morphological feature indicates virtually all ISM removed from disk by ram pressure

Morphological Tracers of RPS • The Tail – ISM removed from disk has formed tail, ISM has been displaced downwind over past 10 – 200 Myr

Morphological Tracers of RPS • Extraplanar UV Regions – SF in stripped gas over past ~350 Myr (most within past 100 Myr)

Derived Evolu6onary Timescales • Leading Edge: 200 – 400 Myr to strip from >8 – 5 kpc • Trailing Side: No age gradient

Derived Evolu6onary Timescales • Tail Evolu6on: 10 – 300 Myr for ISM to move downwind from UV/H α to current posi6on

Derived Evolu6onary Timescales • Extraplanar UV regions – all formed <400 Myr ago

Stripping History • RP increased rapidly ~200 – 400 Myr ago • Gas stripped from >8 – 5 kpc on leading side • Disk stripped asymmetrically ‐ more deeply on leading side than trailing side (traced by UV) • Ader ~1 rota6onal period (400 Myr), gas now more symmetric (traced by HI and H α ) • Within past ~400 Myr, gas has led the trailing side of the disk to form the base of the tail, tail has con6nued to move from disk

Late‐Stage Addi6ons • Current form of SP models • Thoughts on crea6on of thick disk

Late‐stage Addi6on ‐ Treatment of SP Models Open boxes: parameter space made possible by nested doughnut correc7on Filled circles/boxes: measured values

Reminder: Nested Doughnut Correc6on

Late‐stage Addi6on ‐ Crea6on of Thick Disk • In 4330 we observe recent SF that has occurred outside the thin disk In stripped extraplanar gas In tail – downwind of disk plane

Late‐stage Addi6on ‐ Crea6on of Thick Disk • In 4330, recent SF has occurred outside the thin disk • Most stars close enough to the galaxy to remain bound • These will create new halo components – in some cases, the dis6nc6on between the thick disk and halo will be arbitrary • Thick disks made by mergers are older than their embedded thin disks; thick disks made by RPS are younger than their thin disks & have narrow range of stellar ages

Predicted Thick Disk Proper6es • Over a few dynamical 6mes, will spread out to disk of thickness ~2 kpc, radius ~12 kpc, stellar age range few x 100 Myr ~12 kpc Major axis ~2 kpc

Data vs. Models