J/AJ/135/1249 The early spectra of eta Carinae (Humphreys+, 2008)
The early spectra of eta Carinae 1892 to 1941 and the onset of its high
excitation emission spectrum.
Humphreys R.M., Davidson K., Koppelman M.
<Astron. J., 135, 1249-1263 (2008)>
=2008AJ....135.1249H 2008AJ....135.1249H
ADC_Keywords: Stars, Be ; Spectroscopy ; Line Profiles
Keywords: stars: emission-line, Be - stars: individual (η Car) -
stars: winds, outflows
Abstract:
The observed behavior of η Car from 1860 to 1940 has not been
considered in most recent accounts, nor has it been explained in any
quantitative model. We have used modern digital processing techniques
to examine Harvard objective-prism spectra made from 1892 to 1941.
Relatively high excitation HeIλ4471 and [FeIII]4658 emission,
conspicuous today, were weak and perhaps absent throughout those
years. Feast et al. (2001MNRAS.322..741F 2001MNRAS.322..741F) noted this qualitative fact
for other pre-1920 spectra, but we quantify it and extend it to a time
only three years before Gaviola (1953ApJ...118..234G 1953ApJ...118..234G)'s first
observations of the high-excitation features. Evidently the supply of
helium-ionizing photons (λ<504Å) grew rapidly between 1941
and 1944. The apparent scarcity of such far-UV radiation before 1944
is difficult to explain in models that employ a hot massive secondary
star, because no feasible dense wind or obscuration by dust would have
hidden the photoionization caused by the proposed companion during
most of its orbital period. We also discuss the qualitative
near-constancy of the spectrum from 1900 to 1940, and η Car's
photometric and spectroscopic transition between 1940 and 1953.
Description:
Harvard objective prism plates :
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Series Telescope Scale("/mm) Dates Location
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A 24inch Bruce Doublet 60 1896-1926 Peru
A 1929-1950 South Africa
B 8inch Bache Doublet 179 1891-1923 Peru
B 1930-1954 South Africa
X 13inch Boyden Refractor 42.4 1891-1926 Peru
X 1930-1951 South Africa
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Objects:
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RA (2000) DE Designation(s)
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10 45 03.6 -59 41 04 eta Carina = V* eta Car
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 116 112 The Harvard objective prism plates of Eta Car
orig_sp/* . 33 Original scans of digitized spectra (fits)
rect_sp/* . 12 Examples of the rectified spectra of the scans (fits)
tracings/* . 22 Extracted 1D tracings with wavelength calibration
for the spectra (pdf)
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See also:
J/ApJS/181/473 : Analysis of the spectrum of eta Car (Nielsen+, 2009)
J/AJ/135/1249 : The early spectra of eta Carinae (Humphreys+, 2008)
J/A+A/419/215 : Emission lines of eta Car (Hartman+, 2004)
J/A+AS/133/299 : Long-term spectroscopy of eta Carinae (Damineli+ 1998)
http://archive.stsci.edu/prepds/etacar/ : HST treasury program on eta Car
http://etacar.umn.edu/ : eta car research group site
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Plate Plate number (A,B, or X + NNNNN)
8 A1 --- n_Plate [b] means "digitized"
10- 19 A10 "YYYY/MM/DD" Date Calendar date of observation
21- 27 I7 JD JD Julian date of observation
29- 31 I3 min texp ?=- Exposure time
33- 36 F4.2 --- Phase Phase in the 5.5yr spectroscopic cycle
38- 77 A40 --- Comm ?=--- Comments about the spectrum
80 A1 --- n_Comm Note on spectral features (1)
82- 92 A11 --- OrigSp Original scan of digitized spectrum
94-105 A12 --- RectSp Example of the rectified spectrum of
the scan
107-116 A10 --- Tracings Extracted 1D tracings with wavelength
calibration for the spectrum
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Note (1): Flags as follows:
a = Weak absorption line spectrum; Hβ, Hγ, Hδ,
[FeII]4359Å emission lines.
c = Absorption lines barely discernible; Hβ, Hγ emission.
d = Absorption lines very weak or gone; Hβ, Hγ, Hδ,
[FeII]4359Å emission lines.
e = Hydrogen, FeII, [FeII] emission.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 13-Jul-2010