Red Supergiants as Extragalactic Abundance Probes: Establishing the J-Band TechniqueZach Gazak

Rolf Kudritzki (chair), Josh Barnes, Fabio Bresolin, Ben Davies, Lisa Kewley, John Learned, John Rayner

Red Supergiants as Extragalactic Abundance Probes: Establishing the J-Band Technique

Rogelio Bernal Andreo (DeepSkyColors.com)

α Orionis (Betelgeuse)

Metallicity gradients of star forming galaxies:

Extragalactic Chemical Abundances

Key targets for understanding galaxy formation and evolution

Important input for modeling

galaxy evolution

Mass - Metallicity and Mass - Gradient

relationship

M31

Jerry Lodriguss

Ken Crawford

M33

M81

Giovanni Benintende

NGC 2403

Subaru

Metallicity gradients of star forming galaxies:

Extragalactic Chemical Abundances

Typically measured using highly uncertain “strong line” methods of collisional lines in H II

regions:

Problems with these methods include:I. Troublesome calibration

II. Abundance discrepancies

III. Line saturation degeneracies

Collisional line methods from H II regions

I: Troublesome Calibration

Results depend heavily on choice of calibrationNGC 300 (ESO)

Collisional line methods from H II regions

I: Troublesome Calibration

Results depend heavily on choice of calibrationNGC 300 (ESO)

Bresolin et al. 2009

Collisional line methods from H II regions

I: Troublesome Calibration

Results depend heavily on choice of calibrationNGC 300 (ESO)

Kewley & Ellison 2008

Collisional metallicities 0.2 to 0.4 dex lower than recombination measurements.

II: Abundance Discrepancy Factor

Simon-Diaz & Stasinska 2010

Dust composition

Collisional metallicities 0.2 to 0.4 dex lower than recombination measurements.

II: Abundance Discrepancy Factor

Simon-Diaz & Stasinska 2010

Peimbert et al. 2006

Dust composition

Degeneracy at over ~0.5 solar metallicity

III: Line Saturation

Stasinska 2010

[OIII] and [NII] [NII] only

Significant Discrepancies

Stasinska 2010

[OIII] and [NII] [NII] only

Simon-Diaz & Stasinska 2010

M33: U et al. 2009A and B Supergiants

Significant Discrepancies

Stasinska 2010

[OIII] and [NII] [NII] only

Simon-Diaz & Stasinska 2010

M33: U et al. 2009A and B Supergiants

+ HII Regions

Stars drive chemical enrichment

Evolution of galaxies

Abundance pattern gradients

Interstellar extinction

Distances

Quantitative Spectroscopy of Stars

8 < Minit < 35 Msun

Red Supergiants

B8-A4

K–M

MJ -8 to -11

Cool: Teff < 4500 K

Inflated: R on AU scales

Convection + Mass Loss

Red Supergiants

ESO

Betelgeuse

ESO & P. Kervella

Historically, high resolution (R~20,000) required.

Unrealistic extragalactic integration times!

Davies, Kudritzki & Figer 2010:

We can use R~3000 in J band, log[Z] to 0.1 dex

Spectroscopy of RSGs

Peak RSG flux and strong, well separated linesRSGs in the J Band

3500 K

J band

Peak RSG flux and strong, well separated linesRSGs in the J Band

3500 K

J band

R~2500 SpeX (Rayner et al. 2009)

HD 39801

MARCS model grid: Spherical symmetry, LTERSGs in the J Band

R~2500 SpeX (Rayner et al. 2009)

HD 39801

MARCS model grid: Spherical symmetry, LTERSGs in the J Band

R~2500 SpeX (Rayner et al. 2009)

HD 39801

Teff: 3750 +/- 220 (3710)

log[Z]: 0.16 +/- 0.28 (0.19 +/- 0.21)

Finding RSGs

Image Courtesy of Mike Bessell

LMC

Ben Davies

M33

M33

M33

Thesis work:I. The Milky Way

II. Local Group Galaxies

III. Beyond the Local Group

Solar metallicity Perseus OB1 RSGs

M31 (Milky Way analog)M33 (sub-solar metallicities)

M81 (super solar metallicities)NGC2403 (sub-solar metallicities)Super Star Clusters (SSCs)

I. Solar Neighborhood: Per OB-1

20+ RSGs

I. Solar Neighborhood: Per OB-1 Observe full RSG population at high and low

resolution

Compare and calibrate high-R v. low-R methods

Calibrate to well established BSG techniques

J, H at R~20,000: IRCS on Subaru (1 night)R~ 2,500: SpeX on IRTF (1 night)

MARCS model gridDevelop analysis techniques

Collaborate with Urbaneja, Kudritzki: spectra of all known BSGs in Per OB1

I. Solar Neighborhood: Per OB-1

Critical dataset for this work and into the future

Test and calibrate new future RSG atmosphere codes

II. Galactic Neighborhood: M31, M33

M31

Jerry Lodriguss

M33

Ken Crawford

Metallicity gradients of Local Group

galaxies using RSGs

Milky Way analog

Very little spectroscopic information over the radial gradient.

1000s of RSGs

II. Galactic Neighborhood: M31, M33

M31

Jerry Lodriguss

2 nights with MOSFIRE on Keck I:Full coverage of radial metallicity gradient with detailed information on α/Fe element

ratios.

II. Galactic Neighborhood: M31, M33

M33

Ken Crawford

1 night with MOSFIRE on Keck I:Cover radial gradient with brightest RSGs, allowing a critical test of conflicting results between HII and BSGs.

M33: U et al. 2009A and B

Supergiants

+ HII Regions

Abundance gradient of M81 or NGC 2403

III: Beyond the Local Group

M81

Giovanni Benintende

NGC 2403

Subaru

III: Beyond the Local GroupM81

Giovanni Benintende

4 Mpc

Indications of super-solar central metallicity and shallow gradient

1000s of RSGs3 nights with MOSFIRE on Keck I:Mass-metallicity relationship from RSGs (with

LG work)

Spiral galaxy metallicity gradients independent of mass if considered on a dimensionless length scale?

105 Msun with ~100 RSGs: reach 10x distances

IIIb: Super Star Clusters

M82: McCrady & Graham 2007

105 Msun with ~100 RSGs: reach 10x distances

IIIb: Super Star Clusters

Perseus OB1 work will allow a critical testProceed with additional observations if successful

Promising agreement with M51 SSC photometry from Nate Bastian

RSGs with Extremely Large Telescopes

Evans et al. 2010

Limiting mJ ~23 means RSGs beyond Virgo Cluster

RSGs with Extremely Large Telescopes

Evans et al. 2010

Limiting mJ ~23 means RSGs beyond Virgo Cluster

RSGs with Extremely Large Telescopes

Excellent recovery of metallicity (Evans et al. 2010)

Center of Virgo Cluster Gunter Kerschhuber

Thesis Timeline

MOSFIRE backup instrument is FMOS on Subaru