The Photometric and Spectral Evolution of the 2008 NGC 300 Transient
Sponsored Links
This presentation is the property of its rightful owner.
1 / 17

The Photometric and Spectral Evolution of the 2008 NGC 300 Transient PowerPoint PPT Presentation


  • 68 Views
  • Uploaded on
  • Presentation posted in: General

The Photometric and Spectral Evolution of the 2008 NGC 300 Transient. Roberta M. Humphreys University of Minnesota. Discovery April 24, 2008 by Monard. Smarts 1.3m BVRIJHK May 15 – Jun 22, 2009 1.5m spectroscopy May 15 - Jan 22, 2009

Download Presentation

The Photometric and Spectral Evolution of the 2008 NGC 300 Transient

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


The Photometric and Spectral Evolution of the 2008 NGC 300 Transient

Roberta M. Humphreys

University of Minnesota

Discovery April 24, 2008 by Monard

Smarts 1.3m BVRIJHK May 15 – Jun 22, 2009

1.5m spectroscopy May 15 - Jan 22, 2009

Magellan MagE July 6, Aug 30/Sep 1 2008, Jun 05, 2009

The progenitor

Prieto 2008from

Spitzer 2003, 2007


Basic Properties

Pre-eruption IR SED => Lsun = 5.5 x 104 Lsun, Mbol = -7.1 mag

Maximum light mv = 14.7 mag => Mv = -12.1 or -12.9 mag, Av = 0.3 or 1.2

Increased luminosity by ~ 100 times or more

Spectrum at max, F-type supergaint abs line + H, Ca II, [Ca II] emission

Total emitted energy ~ 1047 ergs

Mass of progenitor ? 10 – 15 Msun


The Spectral Energy Distribution

7500 K BB, f-f, 715 K dust

L* = 1.3 x 107 Lsun

R* max = 10AU

Rdust = 1750 AU = 10 light days

Dust survived the initial eruption

observed

corrected


Evolution of the Spectrum– the Eruption

Berger et al. 2009

Bond et al. 2009

F-type supergiant spectrum expected in an eruption forming optically thick wind

At max – complex Ca II profiles, Vel (em and abs) ~ 400 km/s, FWHM of Ha ~ 1000 km/s


Evolution of the Spectrum – Post-Eruption

The Double-Peaked Hydrogen and Ca II Emission Lines

bipolar/asymmetric outflow –

expansion

Ca II primary 79 km/s

secondary 164 km/s

Hydrogen primary 69 km/s

secondary ~ 200 km/s


Ca II and [Ca II] Emission

The Asymmetric [Ca II] profiles

Thomson scattering

Auer and Van Blerkom 1972 demonstrated effect of electron scattering on profiles in expanding ejecta for recombination lines -- asymmetric profiles with red wings.

Hillier 1991


Other Emission Lines

The Absorption Line Spectrum

He I 5876 + other weak em 7065, 6678, 3964, 3888

O I 8446 -- Ly b pumping, by flourescence

[O I] 6300, 6363

Fe II

[Fe II]

O I 7774 (lum sensitive ~ -6.9 Mv )

Sr II, Ca I, Mn I, Ti II, V II

Ba II : 4554, 4934

Na I D (also O I 8446, Berger et al. )

Double Ca II H and K

Expanding envelope becoming transparent to ionizing radiation

Rapid transition from absorption

to emission

Jul 18 (abs)  Sep 08 (em)


Clues from the Velocities

Expected Vel galactic rotation 190 km s-1

Max . 15 May Em. and abs. ~ 400 km s-1

Post-eruption --

Double-peaked profiles ( abs min.Ca II and H)  200 +/- 2.7 km s-1 (14)

Emission lines (Aug/Sep)  200 +/- 4.4 km s-1 (40)

Absorption lines (July)  180 +/- 1.7 km s-1 (33)


Eruption and Post – Eruption

Maximum – redshifted vel ~ 400 km/s

expansion ~ 500 km/s,

Post-eruption – 20 – 30d -- shift to lower vel abs and em lines

Initial eruption followed by a dense slowly expanding false photosphere and asymmetrical bipolar outflow

Abs lines weaken, transition to em (Na I and O I)

100d dense wind becomes transparent to ionizing radiation


Thoughts on the nature of the N300 Transient and origin of instability

Progenitor (IR SED)  a high mass loss state, tip of AGB or supergiant OH/IR star

lack of IRAC variability, outflow velocity (75 km s-1)  post AGB/RSG

Outflow vel. greater than AGB/RSG, lower S Dor vars.

Initial mass -- Lum  10-15Msun, 13-17Msun CMD (Gogarten et al. 2009)

PAH feature/ Ba II?  post AGB, proto-PNe, lower initial mass

But no carbon bands: CH, CN, C2

Origin of the ionizing radiation


Intermediate-mass post -AGB/RSG on a blue loop


Other members of this sub-group

SN2008S

SN2010da

SN2010dn

M85 2006 OT?

M31 RV X

At Maximum:

F-type supergiant spectrum, Ca II and [Ca II] em, dusty progenitors, increased 100 – 1000 times in luminosity


Optically obscured, “cool” transients

NGC 300 2008 OT SN2008s SN2010da

Prieto 2008

Prieto et al 2008

Khan et al., Berger et al. 2010

T= 350K BB

L = 5.5 x 104 Lsun,

Mbol = -7.1 mag

at maximum

Mv = -12.1 or -12.9 mag

L = 1.1 x 107 Lsun

T= 440K BB

L = 3.5 x 104Lsun

Mbol = -6.8 mag

at maximum

Mv = -13.6 mag

L = 3 x 107 Lsun

T= 890 K BB

L = 1.3 x 104 Lsun

Mbol = -5.5 mag

at maximum

Mv = -10.4 mag

L = 1.1 x 106 Lsun

In “eruption” increased 100 – 1000 times


The spectra

SN2010da spectrum

H em, [N II], He I, O I,

Ca II ? No [Ca II] !

He II 4686 !

ATEL 2637 (Chornock & Berger)


These are not LBVs !


A future meeting --

Outstanding Theoretical Problems in Massive Star Research

Minnesota Institute for Astrophysics and

Fine Theoretical Physics Institute

University of Minnesota

October 2012

IMPOSTOR !


A candidate for membership?

UGC 2773 2009 OT

At max ~ 107 Lsun

Increased 22.8 -> 17.5 mR

Progenitor -7.8 Mv

Color -> ~ A-type 1.3 x 105 Lsun

~ 20Msun (CMD)


  • Login