Workshop at STScI, 2011 June 28-30

“Intermediate-Luminosity Red

Transients”

K. Davidson

Workshop at STScI, 2011 June 28-30

“Intermediate-Luminosity Red

Transients”

K. Davidson

Diverse aspects of the

Physics of Eruptions, especially those propelled by Eddington.

or,

Excerpts from The Missing Manual.

Part the first: Radiation temperature.

What does an eruption look like when

it is visually most spectacular ?

How big and how hot is the UV-to-far-red photosphere ?

Question:

Suppose that a stellar wind or eruptive

outflow is

dense enough to be opaque. Then, WHAT IS

THE

RELATION BETWEEN APPARENT RADIATIVE

TEMPERATURE AND MASS-LOSS RATE ? Caveat

Tc = APPARENT temperature or

CHARACTERISTIC temperature.

EFFECTIVE temperature is ill-defined! A LATE-NEOLITHIC CALCULATION …

Fair approximation:

1. Solve spherical scattering problem with F ~ 1/r2, opacity = scattering + absorption, mostly scattering.

2. Assume T(r) = radiation-density temperature.

3. Temperature of escaping radiation = approximately T(thermalization depth).

Of course varying degrees of better approximation can be arranged.

( Another story: The elusive

“Modified Eddington Limit” )

-- FROM THE 1987 PAPER --

LIKE THE PREVIOUS FIGURE, AXES INTERCHANGED

Note: No need for spherical symmetry, steady flow, etc.

Can be an outburst, a bipolar thing, etc.

7000 K* IS A SPECIAL TEMPERATURE

IN THE H-R DIAGRAM.

* (Really meaning 6000—8000 K.)

7000 K IS A SPECIAL TEMPERATURE

IN THE H-R DIAGRAM.

NATURAL LIMIT FOR MASSIVE OUTFLOWS:

-- SNae; LBV’s; Novae; Eta Car; Impostors; … ? --

7000 K IS A SPECIAL TEMPERATURE

IN THE H-R DIAGRAM.

NATURAL LIMIT FOR MASSIVE OUTFLOWS:

-- SNae; LBV’s; Novae; Eta Car; Impostors; … ? --

Analogous to the Hayashi Limit at 3000 K …

7000 K IS A SPECIAL TEMPERATURE

IN THE H-R DIAGRAM.

NATURAL LIMIT FOR MASSIVE OUTFLOWS:

-- SNae; LBV’s; Novae; Eta Car; Impostors; … ? --

Analogous to the Hayashi Limit at 3000 K …

Moreover, B.C. Is close to zero at 5500--7500 K;

allowing visually bright stars.

( memo ) Shaviv plural & novae,

same problem.

SUPER – EDDINGTON FLOWS (CONTINUUM DRIVEN WIND)

Observed characteristics of Eta Car 1836—1858 event:

-- L roughly 2—5 times Eddington for 5—20 years -- Ejected mass 10—20 Msun

-- Radiated energy

-- Kinetic energy

Observed characteristics of Eta Car 1836—1858 event:

-- L roughly 2—5 times Eddington for 5—20 years -- Ejected mass 10—20 Msun

-- Radiated energy

-- Kinetic energy

Set up normal equations, try to make it work.

Observed characteristics of Eta Car 1836—1858 event:

-- L roughly 2—5 times Eddington for 5—20 years -- Ejected mass 10—20 Msun

-- Radiated energy

-- Kinetic energy

Set up normal equations, try to make it work.

Doesn’t work; ejects too much mass, too fast .

Quoting Shaviv...

Quoting Shaviv...

Typo above! Read “sonic radius”, not “shock”

“POROSITY” (N. Shaviv)

Quoting Shaviv...

Result:

Can simulate Eta Car Great Eruption, Novae.

More or less.

Tired old joke: Theorist, “assume a spherical cow...”

Tired old joke: Theorist, “assume a spherical cow...”

21st century version: Theorist, “assume a homogeneous cow...”

Equatorial Skirt

- Granulation with various size scales –

Which are the dense places – Bright or dark? RADIATIVE TRANSFER PROBLEM

SN 2010da: X-rays and He II 4687 ??

-- 30 --

He II 4687

ETA CAR

“EVENT”

2009

2-10 keV X-rays

He II 4687

Refs. for physics of He II 4687, soft X-rays,

and shock breakup:

J. Martin et al, ApJ 640, 474 (2006)

Soker & Behar, ApJ 652, 1563 (2006)

A.Mehner et al, new astro-ph