Eta Carinae: The 2003.5 Observing Campaign

In 2003.5 Eta Carinae, one of the most luminous and massive stars in the Universe, is expected to undergo an X-ray eclipse. This X-ray eclipse is believed to occur every 5.52 years and is apparently correlated with the 5.52 year fading of high excitation lines (like He II 10830 Å published by Augusto Damineli). The X-ray emission is thought to arise at a shock front produced as the wind from Eta Car slams into the wind from a less massive (but hotter) companion star. The eclipse may be produced as the shock front around the companion moves behind the thick wind of Eta Car. The upcoming eclipse marks only the 3rd time the X-ray eclipse has been seen (the first time was a fortuitous observation with ROSAT), and we hope will mark the first time the event is observed by the full complement of ground-based and space based instrumentation. This page summarizes some of the planned observations, and results as they become available.

Papers & Presentations relating to the 2003.5 Campaign

Observations

• X-ray and gamma Ray observations: (X-ray Report)
  • Chandra
  • RXTE
  • XMM-Newton
  • INTEGRAL
• The HST Treasury Program (See the official Eta Car HST Treasury Website at http://etacar.umn.edu)
• Ground-based optical spectrometry and photometry (Optical Report)
  (Also see the AAVSO Eta Car page, which contains links to finding charts, archived lightcurves, images and a great deal of other information)
• IR broad-band monitoring (IR Report)
• Millimeter Monitoring (mm Report)
• Radio monitoring

X-ray & Gamma-Ray Observations

See the X-ray Report for more detailed information about the current status of the X-ray observing campaign

The graph below shows the variation of X-ray emission from Eta Car; the red line shows the expected behavior of the observed X-ray emission if the emission were strictly periodic.

The figure below shows the observed RXTE data from a 1-year interval around the eclipse in 1998 (top) and the expected X-ray lightcurve in a 1 year interval around the 2003.5 eclipse (bottom). Note that we already see deviations in the x-ray behavior compared to last cycle - it's not yet clear what effect these deviations will have on the 2003.5 "event".

The discussion of the X-ray observing plan as it stood in July 2001 and as presented by MFC at the Eta Car: Reading the Legend Workshop (Mt. Rainier, WA, July 10-14 2001) is now available.

Chandra

A) Observation 200219 was observed on October 16, 2002
B) Observation 200215 was observed on May 3, 2003
C) Observation 200218 was observed on Jun 16, 2003
D) Observation 200216 was observed on Jul 20, 2003 
D1) Observation 200237 was observed on Aug 28, 2003
E) Observation 200217 was observed on Sep 26, 2003

RXTE

XMM

1. 5 observations of 8300 seconds each were approved to observed the spectral variation of the star prior to the X-ray eclipse:
   1. 0145740101 8300 2003-01-25@12:40:12
   2. 0145740201 8300 2003-01-27@00:45:34
   3. 0145740301 8300 2003-01-27@20:18:56
   4. 0145740401 9800 2003-01-29@01:22:23
   5. 0145740501 8300 2003-01-29@23:36:58
2. 2 TOO observations have been granted to observe the X-ray eclipse ingress:
   1. 41200 sec on 2003-06-08@12:42:14
   2. 32700 sec on 2003-06-13@23:33:50
3. Observation 14578 (ObsID 0145780101 an AO2 triggered observation during eclipse) has been scheduled in revolution 662, i.e. start at 2003-07-22@01:33:19.
4. 3 AO3 observations to study the change in the X-ray spectrum during recovery have been accepted:
   1. 0160560101 2003-08-02T20:42:53
   2. 0160560201 2003-08-09T01:25:59
   3. 0160560301 2003-08-18@15:05:13

INTEGRAL

Date: Mon, 23 Jun 2003 14:08:12 +0200
To: ybutt@cfa.harvard.edu, inthelp@rssd.esa.int
Subject: INTEGRAL SCHEDULE NOTIFICATION

Dear Integral Observer,

Your  observation belonging to proposal 0120039 has been 
scheduled as follows:

Start time (UTC)    | Source       | RA (J2000) | Dec (J2000)
2003-06-24 18:55:33 | eta Carinae  | 10:45:03.6 | -59 43 03.0 
End time
2003-06-28 08:53:30

Total elapsed duration 200200sec

For more details we refer to the Integral short-term plan on the
web, available on:
http://astro.estec.esa.nl/integral_webapps/index.jsp?future

June 25 Update: The INTEGRAL observation has been split into two 100 ksec observations, one on June 24 and one on July 3 in order to study the variability of the source after the beginning of the X-ray minimum.

HST Treasury Observations

See the Eta Car HST Treasury Website at http://etacar.umn.edu

Ted Gull has provided the schedule of HST Treasury observations

The figure on the left shows (approximately) the distribution of STIS observations as a function of X-ray phase, compared to the RXTE X-ray lighcurve. The figure on the right shows the distribution of STIS observations vs. phase compared to 2 published radial velocity curves, one by Damineli et al. (2000) and one by Corcoran et al. (2001).

Infrared Observations

Date: Sat, 18 Jan 2003 18:33:41 +0200 (SAST)
From: Patricia Whitelock 
To: "Michael F. Corcoran" 
cc: MWF , ,
   Patricia Whitelock 
Subject: Re: Eta Car RXTE monitoring through Jan 15


Hi Mike

I expect we will be able to monitor eta Car in JHKL as follows:
January 21 - 31,
February 1 - 3, 18 - 28,
March 1 - 3, 11 - 17,
April 15 - 28,
May 13 - 19,
June 3 - 30.
That is the end of the current allocation period. I will apply
for time in July as well of course, but will not know about that
for a few months.

It is our intention to get one JHKL observation per night whenever
possible. 

Regards
Patricia

-- 
Dr Patricia Whitelock                                         
Acting Director                                               
South African Astronomical Observatory                        
P O Box 9                               Phone: +27 21 4609318
7935 Observatory                        Fax: +27 21 4473639   
South Africa                            email: paw@saao.ac.za 

Millimeter Observations

From: "Zulema Abraham" 
Subject: Re: Eta CAr is dissapearing at the 7 mm continuum also
Date: Mon, 23 Jun 2003 18:34:00 -0200

Hi Mike
        I will be observing every day, weather allowing

Zulema

Radio Observations

Date: Wed, 21 May 2003 13:36:07 -0400 (EDT)
From: Stephen White 
Subject: Eta's radio light curve

The 8 GHz radio light curve and movie at 


   http://www.astro.umd.edu/~white/images/eta_time_full.html
   
   
have been updated for an Australia Telescope Compact Array
observation last week (the observation was shorter 
than usual so the image is not quite as good as the others). The radio flux
continues to be markedly lower than at the same stage of the previous cycle
and may bottom out below the last minimum, but possibly not below the previous 
minimum. Observations are now possible at 22 GHz as well, and the preliminary
images show in addition to the main source identified with the star/s a 
bright second source 0.5 arcsec to the west-north-west.

Stephen White, Bob Duncan, Jessica Chapman and Baerbel Koribalski.




Date: Wed, 17 Apr 2002 18:31:58 -0400 (EDT)
From: Stephen White
Subject: radio evolution of Eta
X-Sun-Charset: US-ASCII


We have updated the radio light curve and movie for Eta Carinae at

   
http://www.astro.umd.edu/~white/images/eta_time_full.html

with the most recent observation being last week. The radio flux
is about half what it was at the same stage of the previous cycle: we 
interpret this as less ionizing flux getting out to the outflowing gas on
this side of the system.

Stephen White and Bob Duncan

Ground Based Optical Spectrometry and Photometry

• See Augusto Damineli's web page discussing observations during the upcoming eclipse, along with his observations of the He I 10830 line variations which he used to discover the 5.52-year periodicity. Augusto has also posted the schedule of observations from March to August 2003.

  Augusto reports:

  From: "Augusto Damineli" 
  Subject: Recent spectra of eta Carinae
  Date: Wed, 21 May 2003 13:15:49 -0300
  
  
  Dera eta fans,
  
  I put results of new spectra from eta Car
  collected at LNA/Brazil  on 12-15/May.
  
  The event is progressing smoothly, as 
  can be seen at:
  
  www.etacarinae.iag.usp.br
  
  (click on "The 2003.5 event")
  
  The radial velocity of HeI 6678 broad component
  shows short scale flictuations. I have more data 
  to reduce and check this.
  
  Augusto 
  

• Dra. Virpi Niemela of the Universidad Nacional de La Plata (La Plata, Argentina) writes:

  From: Virpi Niemela
  Subject: Eta Car optical imaging
  Date: Thu, 23 Jan 2003 14:22:10 -0300 (ART)
  
  Hi Mike,
  I have enrolled graduate and undergraduate students for the Eta Car
  observing campaign. Weather permitting, they will be monitoring Eta Car
  during next weekend, when XMM will also observe Eta....
  
  Also CASLEO observers have obtained spectra, high resolution (blue) 
  last week and low resolution (red) this week.
  cheers,
  Virpi
  

  The web page http://lilen.fcaglp.unlp.edu.ar/EtaCar/ summarizes the optical observations of Eta Car from the La Plata Observatory

• Sebastian Otero has a web page with his lightcurve of Eta Car, including data from Stan Walker and Harry Williams, at http://ar.geocities.com/varsao/Curva_Eta_Carinae.htm

• Dr. Otmar Stahl (Uni. Heidelberg) reports on ESO VLT observations with the UV-Visual Echelle Spectrograph (UVES):

  (PI Kerstin Weis, CoIs O. Stahl, D. Bomans, K. Davidson, R. Humphreys, T. Rivinius, Ted Gull, A. Kaufer)
  
  With the ESO VLT telescope and the UVES spectrograph, we obtain
  long-slit, high spatial and high spectral resolution (40,000) spectra
  of eta Car and its ejecta during the 2003.5 event.  The spectra cover
  in two setting almost the full optical spectral range.
  
  The aim is to obtain high-quality long-slit observations along the
  major axis, critical for understanding the latitude dependence of the
  star's bimodal wind during the event. We monitor the changes in the
  central object via the reflected light of the star (or stellar wind)
  along the major axis of the Homunculus, including region FOS4.
     
  We obtain data at approximately one month intervals beginning in
  December 2002, and at about one week intervals close to the event. For
  each observation the slit is aligned parallel to the major axis of the
  Homunculus and passing through FOS 4 which is about 4 arcseconds SE of
  the central star. A few observations also include a second position
  with the slit passing directly through the central star.