1 / 1

Eta Carinae Objective Prism Plates

Spectra of Eta Carinae from Objective Prism Photographic Plates.

hue
Download Presentation

Eta Carinae Objective Prism Plates

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spectra of Eta Carinae from Objective Prism Photographic Plates Objective prism photographic plates of Eta Carinae (e.g. Humphreys et al 2008, AJ, 135, 1249) were found in the Astronomical Photographic Data Archive (APDA)* located at Pisgah Astronomical Research Institute (PARI). The plates belong to the University of Michigan survey (Houk 1978). These plates were taken from 1968 to 1974 between the 5.54 year cyclic events and therefore represent the usual emission line spectra. The spectrum of Eta Car was extracted from each of the objective prism plates. J.D. Cline, T. H. Barker, M. W. Castelaz Pisgah Astronomical Research Institute Not-for-profit foundation AAS 212th Meeting. Session 12.01. June 2008 www.pari.edu Eta Carinae Objective Prism Plates Plates taken with Michigan Curtis Schmidt 0.61/0.91-m + 10O prism. 13 Plates in the APDA Archive from 1968 to 1974 E A F B C G Red Spectrum Scanned image of objective prism plate number CTIO-10464 H D Example of a scanned spectrum of Eta Car. This spectrum is from CTIO-10464 Discussion Results • Absorption components attributed to P Cyg profile (Thackeray 1953) are measured. Average velocity (shown below) for CTIO plate 10464 = -461 km/sec. Velocities for each profile are designated below lines. • Scanning and Spectrum Extraction • Each spectrum of Eta Car was scanned at 4800 ppi with a commercial scanner (MicroTek i800) • scanner resolution is 0.6 Å/pixel, and prism spectral resolution is 2Å • Scanned images wavelength calibrated based on hydrogen and helium lines. • Accuracy of wavelength calibration checked with Harvard Plate X17482 from Humphreys et al (2008) and the comparison is shown in Figure H. Velocities from measured P Cyg components • Average velocity is -521 km/s +/- 60 km/s • Expansion since the Great Eruption (160 years ago; Thackery 1953) based on -521 km/s is 7 x 1016 km or about 8 arcseconds for a distance of 2.3 kpc (Humphreys et al 2008) • 8 arcseconds is consistent with the angular size of the Homunculus Nebula (IIshibashi et al. 2003, AJ, 125, 3222) -558 km/s -371 km/s • Helium line at 4471 Å • The helium emission line at 4471 Å marked by arrows in spectrum plots in Figures A-H. • Not prominent in the spectra • Consistent with results from Humphreys et al (2008) who measured spectra from plates taken between 1892 and 1941 * -497 km/s -433 km/s • The Astronomical Photographic Data Archive • North American astronomical photographic data collections stored at PARI • Rescue, archive, index, make astronomical photographic data avaliable • http://www.pari.edu/library/astronomical-plate-center; Contact: mcastelaz@pari.edu -493 km/s -414 km/s

More Related