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The Physical Properties of Red Supergiants. Emily Levesque IfA, University of Hawaii/SAO, Harvard. Hot Massive Stars: A Lifetime of Influence Lowell Observatory 10.13.08. Collaborators: Philip Massey (Lowell Observatory) Knut Olsen (NOAO) Bertrand Plez (Université de Montpellier)

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the physical properties of red supergiants

The Physical Properties of Red Supergiants

Emily Levesque

IfA, University of Hawaii/SAO, Harvard

Hot Massive Stars: A Lifetime of InfluenceLowell Observatory 10.13.08

slide2

Collaborators:

Philip Massey (Lowell Observatory)

Knut Olsen (NOAO)

Bertrand Plez (Université de Montpellier)

Eric Josselin (Université de Montpellier)

Andre Maeder (Geneva Observatory)

Georges Meynet (Geneva Observatory)

Geoff Clayton (Louisiana State University)

Dave Silva (NOAO/TMT)

Brian Skiff (Lowell Observatory)

slide3

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?
  • What is a red supergiant?
          • Red supergiants are a He-burning evolutionary stage of moderately high-mass (10 - 40 M) stars.
  • physically largest stars in the universe
  • high visual luminosities (MV = -6 to -9) allow study beyond our galaxy
  • populate upper right region of HRD
slide4

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Red Supergiants and the H-R DiagramWhy are we interested in them?

Massive star evolutionary tracks didn’t agree with the position of red supergiants on the H-R diagram.

slide5

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Hayashi limit 

Levesque et al. 2005

slide6

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

forbidden region

Levesque et al. 2005

slide7

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Red Supergiants and the H-R DiagramWhy are we interested in them?

Massive star evolutionary tracks don’t agree with the position of red supergiants on the H-R diagram.

Why?

- Difficulties with the evolutionary tracks:

uncertain opacities

highly extended atmosphere

high-velocity convective layers

- …or problems with the observationally-determined location of these stars

slide8

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Levesque et al. 2005

slide9

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Fitting Red Supergiant Spectra

How do I get the parameters from spectral fitting?

slide10

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Fitting Red Supergiant Spectra

How do I get the parameters from spectral fitting?

TiO band strengths

slide11

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Fitting Red Supergiant Spectra

How do I get the parameters from spectral fitting?

slide12

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

We can fit spectrophotometry of RSGs

with the MARCS stellar atmosphere models:

Levesque et al. 2005

K2 I  4000 K

K5 I  3750 K

M1 I  3625 K

M3 I  3500 K

slide13

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Levesque et al. 2005

slide14

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

What we observe: , ,

Determining Physical Properties

MW

What we want:

slide15

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Levesque et al. 2005

slide16

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Levesque et al. 2005

slide17

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

adapted from Levesque et al. 2005

Dust and Red Supergiants

Excess NUV flux, correlated with high “excess” reddening  excess circumstellar dust

slide18

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

For Milky Way RSGs, dust production rate is about8.5 x 10-9 M yr-1 kpc2

In starburst galaxies at large lookback times, we would expect RSGs to be major contributors to the ISM

Dust and Red Supergiants

  • What are the mechanisms that drive this dust production?
  • How does this mass-loss relation change with metallicity?
  • What reddening law does the dust follow? How does this affect our determinations of RSG luminosities?
slide19

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

VY Canis Majoris: a particularly unusual RSG-extraordinarily luminous -large dust reflection nebula, high mass loss rate -previous work assigned a very cold temperature (2800 K)

slide20

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

VY CMa

!

adapted from Massey et al. 2006

slide21

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

VY Canis Majoris: a particularly unusual RSG-extraordinarily luminous -large dust reflection nebula, high mass loss rate -previous work assigned a very cold temperature (2800 K)

We measured a much warmer temperature of ~3650 K, which in turn suggests a much smaller radius and a lower luminosity.

(note additional fit in the blue, showing a disparity between red and blue lines)

VY CMa

3650 K

3450 K

Massey et al. 2006

slide22

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

adapted from Massey et al. 2006

but…

slide23

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

…our luminosity estimate is contradicted by VY CMa’s measured thermal dust emission

  • luminosity of dust emission is ~5 times higher than our reported VY CMa luminosity!
  • suggests our measure of the luminosity is too low

One explanation: If the circumstellar dust envelope is large-grain and “grey”, this would lead to our underestimate of VY CMa’s luminosity.

Smith et al. 2001

slide24

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

LMC

Levesque et al. 2006

Red Supergiants in the Magellanic Clouds

slide25

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

0.47Z

LMC

LMC

Levesque et al. 2006

Levesque et al. 2006

0.27Z

Red Supergiants in the Magellanic Clouds

SMC

Levesque et al. 2006

slide26

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Milky Way 

SMC 

LMC 

Red Supergiants in the Magellanic Clouds

Levesque et al. 2006

slide27

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

LMC

Levesque et al. 2006

0.47Z

0.47Z

New effective temperature scales give much better agreement with the LMC:

LMC

LMC

Levesque et al. 2006

slide28

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

0.47Z

New effective temperature scales give much better agreement with the LMC:

LMC

LMC

Levesque et al. 2006

slide29

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

LMC

Levesque et al. 2006

0.27Z

But when it comes to the SMC…

SMC

Levesque et al. 2006

slide30

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.27Z

There’s still a few problems…

SMC

Levesque et al. 2006

slide31

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.27Z

There’s still a few problems…

weaker MS stellar winds at low metallicity

increased rotational mixing as a result

enhanced He abundance from mixing

SMC

Levesque et al. 2006

slide32

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

0.47Z

The cool new LMC RSG: WOH G64

van Loon et al. (2005) placed it similarly to VY CMa…

LMC

LMC

Levesque et al. 2006

slide33

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

0.47Z

The cool new LMC RSG: WOH G64

Ohnaka et al. (2008) recently updated its luminosity…

LMC

LMC

Levesque et al. 2006

slide34

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

0.47Z

0.47Z

The cool new LMC RSG: WOH G64

?

We suspect that Teff still needs to be re-examined…

LMC

LMC

Levesque et al. 2006

slide35

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

The average RSG subtype in the Clouds shifts to earlier types with decreasing metallicity:

Z

Milky Way

K0-1 K2-5 K5-7 M0 M1 M2 M3 M4 M5

adapted from Massey & Olsen 2003

slide36

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

The average RSG subtype in the Clouds shifts to earlier types with decreasing metallicity:

0.47Z

LMC

K0-1 K2-5 K5-7 M0 M1 M2 M3 M4 M5

adapted from Massey & Olsen 2003

slide37

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

The average RSG subtype in the Clouds shifts to earlier types with decreasing metallicity:

0.27Z

SMC

K0-1 K2-5 K5-7 M0 M1 M2 M3 M4 M5

adapted from Massey & Olsen 2003

slide38

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

K2 I

K5 I

M1 I

M3 I

Levesque et al. 2005

Levesque et al. 2005

Shift in Spectral Subtype

1) Line depth effects from changing metallicity

slide39

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Milky Way 

SMC 

LMC 

Shift in Spectral Subtype

1) Line depth effects from changing metallicity

Levesque et al. 2006

3650 K  M2 I (MW), M1-1.5 I (LMC), K5-M0 I (SMC)

slide40

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Shift in Spectral Subtype

2) Metallicity-dependent shift of Hayashi limit

Limits of hydrostatic equilibrium get warmer at lower metallicities, imposing limits on how cool (and hence, how late-type), massive stars can get…

Milky Way

Levesque et al. 2006

slide41

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Shift in Spectral Subtype

2) Metallicity-dependent shift of Hayashi limit

Limits of hydrostatic equilibrium get warmer at lower metallicities, imposing limits on how cool (and hence, how late-type), massive stars can get…

LMC

Levesque et al. 2006

slide42

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Shift in Spectral Subtype

2) Metallicity-dependent shift of Hayashi limit

Limits of hydrostatic equilibrium get warmer at lower metallicities, imposing limits on how cool (and hence, how late-type), massive stars can get…

SMC

Levesque et al. 2006

slide43

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

The Late-Type Red Supergiant Sample

Despite evolutionary limitations, some Cloud RSGs are later than would be expected

Investigated the properties of 7 late-type LMC stars and 5 late-type SMC stars, reobserved in 2005

SMC 055188

M 3-4

SMC average is K5-M0

LMC 143035

M 4.5

LMC average is M 1

Levesque et al. 2007

slide44

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Date of Observation2004

Spectral Type:K0 I

Temperature:4300 

Reddening (AV):1.35 

V magnitude:11.84 

Bolometric magnitude:-9.1 

HV 11423- an unusual find in the SMC

slide45

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

slide46

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

slide47

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

slide48

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

2004

slide49

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

2005

Be sure to say what it’s doing explicity HERE; don’t wait until the next slide: warmer = brighter, dustier, more luminous

slide50

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423
  • Where to next?

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Massey et al. 2007

Date of Observation2004  2005

Spectral Type:K0 IM4 I

Temperature:4300  3500

Reddening (AV):1.35  0.10

V magnitude:11.84  12.46

Bolometric magnitude:-9.1  -8.5

HV 11423- an unusual find in the SMC

When HV 11423 getswarmer it is also brighter, dustier, and moreluminous.

Be sure to say what it’s doing explicity HERE; don’t wait until the next slide: warmer = brighter, dustier, more luminous

slide51

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Mo I

K2-3 I

M2 I

M3-4 I

M4.5 I

M2 I

M1.5 I

M4.5 I

M4.5 I

Levesque et al. 2007

Three more “unusual finds”…

Two more SMC stars and one LMC star exhibitthe same unusual behaviors: when these stars are warmer they are also brighter,dustier, and moreluminous.

While V variability in RSGs is common, such spectral variability is unheard of!

slide52

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Three more “unusual finds”…

Two more SMC stars and one LMC star exhibitthe same unusual behaviors: when these stars are warmer they are also brighter,dustier, and moreluminous.

2004

Levesque et al. 2007

slide53

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Three more “unusual finds”…

Two more SMC stars and one LMC star exhibitthe same unusual behaviors: when these stars are warmer they are also brighter,dustier, and moreluminous.

2005

Levesque et al. 2007

slide54

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Three more “unusual finds”…

Two more SMC stars and one LMC star exhibitthe same unusual behaviors: when these stars are warmer they are also brighter,dustier, and moreluminous.

Levesque et al. 2007

We suspect that these stars are in a unique unstable evolutionary state not previously observed in red supergiants.

slide55

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Where To Next?

Continuing to expand our metallicity range

In published work: factor of 4

In Local Group: factor of 15!

slide56

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Where To Next?

Continuing to expand our metallicity range

In published work: factor of 4

In Local Group: factor of 15!

M31: 2Z

2Z

slide57

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Where To Next?

Continuing to expand our metallicity range

In published work: factor of 4

In Local Group: factor of 15!

M31: 2Z…Z?

Z

slide58

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Where To Next?

Continuing to expand our metallicity range

In published work: factor of 4

In Local Group: factor of 15!

M31: 2Z…Z?

WLM: 0.12Z

Local Group Galaxy Survey

slide59

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?

Where To Next?

Continuing to expand our metallicity range

In published work: factor of 4

In Local Group: factor of 15!

M31: 2Z…Z?

WLM: 0.12Z

Improved studies of RSGs and dust

Study these variables in more detail!

  • - What effect does this behavior have on stellar yields and mass-loss-dependent properties?
  • - What new properties and environmental effects should evolutionary models strive to accommodate?
  • - What will these variable stars evolve into?
questions

Galactic RSGs

  • - Teff scale
  • - H-R Diagram
  • - Dust & VY CMa
  • Cloud RSGs
  • - H-R Diagram
  • - WOH-G64
  • - Spectral types
  • HV 11423 & Co.!
  • Where to next?
Questions?

Mountains from the Cerro Tololo 4-meter