J/AJ/150/109 Spectroscopy of η Car in 2009 (Richardson+, 2015)
The optical wind line variability of η Carinae during the 2009.0 event.
Richardson N.D., Gies D.R., Gull T.R., Moffat A.F.J., St-Jean L.
<Astron. J., 150, 109 (2015)>
=2015AJ....150..109R 2015AJ....150..109R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, early-type ; Stars, luminous ;
Stars, nearby ; Equivalent widths
Keywords: binaries: general - stars: early-type - stars: individual: * eta Car -
stars: winds, outflows
Abstract:
We report on high-resolution spectroscopy of the 2009.0 spectroscopic
event of η Carinae collected via SMARTS observations using the
CTIO 1.5m telescope and echelle spectrograph. Our observations were
made almost every night over a two-month interval around the
photometric minimum of η Car associated with the periastron
passage of a hot companion. The photoionizing flux of the companion
and heating related to colliding winds causes large changes in the
wind properties of the massive primary star. Here we present an
analysis of temporal variations in a sample of spectral lines that are
clearly formed in the wind of the primary star. These lines are
affected by a changing illumination of the flux of the secondary star
during the periastron passage. We document the sudden onset of
blueshifted absorption that occurred in most of the lines near or
slightly after periastron, and we argue that these absorption
components are seen when we view the relatively undisturbed wind of
the foreground primary star. We present time series measurements of
the net equivalent width of the wind lines and of the radial
velocities of the absorption trough minima and the emission peak
midpoints. Most lines decrease in emission strength around periastron,
and those high excitation lines formed close to the primary exhibit a
red-ward velocity excursion. We show how these trends can be explained
using an illuminated hemisphere model that is based on the idea that
the emission originates primarily from the side of the primary facing
the hot companion.
Description:
We obtained high signal-to-noise observations with the CTIO 1.5m
telescope and fiber-fed echelle spectrograph operated by the SMARTS
Consortium (R∼40000) almost nightly during the 2009 spectroscopic
minimum and periastron passage of η Car (a total of 40 spectra
between 2008 December 18 and 2009 February 19). The reductions were
described in Paper 1 (Richardson et al., 2010AJ....139.1534R 2010AJ....139.1534R).
Objects:
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RA (ICRS) DE Designation(s)
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10 45 03.55 -59 41 04.0 * eta Car = HD 93308
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ions.dat 11 16 Ions/lines list
table2.dat 51 676 Wind line measurements
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See also:
J/ApJ/751/73 : Equivalent widths in η Car in 1998-2012 (Mehner+, 2012)
J/A+A/540/A133 : η Car emission spectrum (1700-10400Å) (Zethson+, 2012)
J/other/NewA/15.108 : η Car UBVRIHa light curves in 2009
(Fernandez-Lajus+ 2010)
J/ApJS/181/473 : Analysis of the spectrum of η Car (Nielsen+, 2009)
J/ApJS/163/173 : UV spectrum of eta Car in 2003.5 (Gull+, 2006)
J/AJ/129/2018 : RXTE scaled fluxes of eta Car (Corcoran+, 2005)
Byte-by-byte Description of file: ions.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Ion The ion identifier
8- 11 I4 0.1nm Line [4922/7065]? Line wavelength (in Å)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Ion The ion identifier (FeII, HeI, Hα, NII, or
SiII)
8- 11 I4 0.1nm Line [4922/7065]? Line wavelength (in Å)
13- 20 F8.3 d HJD [755/1361] Heliocentric Julian Date (HJD-2454000)
22- 27 F6.3 --- Phase [11.957/12.256] Phase
29- 36 F8.3 0.1nm EW [-650.3/1.64]? Equivalent width (in Å) (1)
38- 44 F7.1 km/s Vmin [-1028.7/-208.3]? Minimum velocity (2)
46- 51 F6.1 km/s Vb [-334.4/150.3]? Estimated bisector velocity (3)
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Note (1): We measured the equivalent widths of ten optical wind lines during the
time of the photometric minimum. See Section 4.1 for further details.
Note (2): Set by finding the zero crossing in the numerical derivative of a
smoothed version of the spectral lines. See Section 4.2 for more details.
Note (3): At ∼20% of the peak height above the continuum. See Section 4.3 for
additional details.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 26-Oct-2015