J/ApJ/954/65 EWs of eta Carinae from ∼30yrs sp. monitoring (Damineli+, 2023)
The long-term spectral changes of eta Carinae: are they caused by a dissipating
occulter as indicated by a dissipating occulter as indicated by CMFGEN models?
Damineli A., Hillier D.J., Navarete F., Moffat A.F.J., Weigelt G.,
Corcoran M.F., Gull T.R., Richardson N.D., Ho P., Madura T.I.,
Espinoza-Galeas D., Hartman H., Morris P., Pickett C.S., Stevens I.R.,
Russell C.M.P., Hamaguchi K., Jablonski F.J., Teodoro M., McGee P.,
Cacella P., Heathcote B., Harrison K.M., Johnston M., Bohlsen T.,
Di Scala G.
<Astrophys. J., 954, 65 (2023)>
=2023ApJ...954...65D 2023ApJ...954...65D
ADC_Keywords: Stars, giant; Spectra, optical; Equivalent widths
Keywords: Stellar phenomena ; Stellar mass loss
Abstract:
Eta Carinae (η Car) exhibits a unique set of P Cygni profiles with
both broad and narrow components. Over many decades, the spectrum has
changed-there has been an increase in observed continuum fluxes and a
decrease in FeII and HI emission-line equivalent widths. The spectrum
is evolving toward that of a P Cygni star such as P Cygni itself and
HDE 316285. The spectral evolution has been attributed to intrinsic
variations such as a decrease in the mass-loss rate of the primary
star or differential evolution in a latitudinal-dependent stellar
wind. However, intrinsic wind changes conflict with three
observational results: the steady long-term bolometric luminosity; the
repeating X-ray light curve over the binary period; and the constancy
of the dust-scattered spectrum from the Homunculus. We extend previous
work that showed a secular strengthening of P Cygni absorptions by
adding more orbital cycles to overcome temporary instabilities and by
examining more atomic transitions. cmfgen modeling of the primary wind
shows that a time-decreasing mass-loss rate is not the best
explanation for the observations. However, models with a small
dissipating absorber in our line of sight can explain both the
increase in brightness and changes in the emission and P Cygni
absorption profiles. If the spectral evolution is caused by the
dissipating circumstellar medium, and not by intrinsic changes in the
binary, the dynamical timescale to recover from the Great Eruption is
much less than a century, different from previous suggestions.
Description:
The data used to measure equivalent widths (EWs) in this work are
mainly from the facilities described in Section 2 of
Damineli+ (2021, J/MNRAS/505/963).
In addition to the professional facilities, there are a few
observations from amateur astronomers --these are listed in Table 1
and partly described in Teodoro+ (2016ApJ...819..131T 2016ApJ...819..131T).
Objects:
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RA (ICRS) DE Designation(s)
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10 45 03.54 -59 41 03.9 eta Car = Gaia DR3 5350358584482202880
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 17 Observatories
table2.dat 48 1978 Equivalent width table
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See also:
J/A+AS/133/299 : Long-term spectroscopy of eta Carinae (Damineli+ 1998)
J/A+A/343/847 : Geneva Photometry of Eta Car (van Genderen+ 1999)
J/A+A/419/215 : Emission lines of Sr filament near η Car (Hartman+, 2004)
J/AJ/129/2018 : RXTE scaled fluxes of eta Car (Corcoran+, 2005)
J/ApJS/157/138 : UV spectrum of eta Car (Nielsen+, 2005)
J/ApJS/163/173 : UV spectrum of eta Car in 2003.5 (Gull+, 2006)
J/ApJS/168/289 : NUV spectrum of eta Car in 2003.5 (Nielsen+, 2007)
J/AJ/135/1249 : The early spectra of eta Carinae (Humphreys+, 2008)
J/ApJS/181/473 : Analysis of the spectrum of η Car (Nielsen+, 2009)
J/A+A/493/1093 : BVRI light curves of η Car (Fernandez-Lajus+, 2009)
J/other/NewA/15.108 : UBVRIHa of η Car in 2009 (Fernandez-Lajus+ 2010)
J/ApJ/751/73 : Equivalent widths in η Cat in 1998-2012 (Mehner+, 2012)
J/A+A/540/A133 : η Car emission spectrum (1700-10400Å) (Zethson+, 2012)
J/A+A/564/A14 : Near-infrared photometry of η Carinae (Mehner+, 2014)
J/A+A/578/A122 : eta Carinae's 2014.6 spectroscopic event (Mehner+, 2015)
J/ApJ/808/174 : FeII radiative transition rates (Bautista+, 2015)
J/AJ/150/109 : Spectroscopy of η Car in 2009 (Richardson+, 2015)
J/A+A/594/A106 : eta Car velocity-resolved imaging (Weigelt+, 2016)
J/ApJ/838/45 : eta Car obs. around the 2014 X-ray minimum (Corcoran+, 2017)
J/MNRAS/505/963 : Vanishing natural coronagraph of eta Car (Damineli+, 2021)
J/ApJ/914/47 : ISS/NICER X-ray observations of eta Car (Kashi+, 2021)
J/ApJ/933/136 : 0.4-10keV X-ray monitoring of EtaCar (Espinoza-Galeas+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Inst Spectrograph or Observer name
13- 16 F4.2 m Ap [0.2/8] Telescope aperture
18- 20 F3.1 m Ap2 [2.2]? Second telescope aperture for FEROS
22- 25 A4 --- Res Most frequent resolving power
27- 29 I3 --- N5876 [1/186]? Number of measurements used in this
work; HeIλ5875
31- 33 I3 --- N6347 [2/246]? Number of measurements used in this
work; SiIIλ6347
35- 37 I3 --- N8750 [8/141]? Number of measurements used in this
work; HI Pa12 λ8752
39- 41 I3 --- N10830 [140]? Number of measurements used in this
work; HeIλ10830
43- 55 A13 --- Tel Facility or observer as indicated in Table 2;
column added by CDS (1)
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Note (1): SASER = Southern Astro Spectroscopy Email Ring members;
see Teodoro+ (2016ApJ...819..131T 2016ApJ...819..131T)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Species Absorption line ("HI Pa12", "HeI", "SiII")
9- 13 I5 0.1nm lambda [5875/10830] Wavelength of Species
15- 23 F9.3 d HJD [47613.5/59703.5] Heliocentric Julian Date,
HJD-2400000.0 (1989-03-28 to 2022-05-03 UTC)
25- 29 F5.2 0.1nm EWSp [-0.02/24.6] Equivalent width of Species,
Angstroms
31- 34 F4.2 0.1nm e_EWSp [0/1.3] Uncertainty in EWsp
36- 48 A13 --- Tel Facility for measurement
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History:
From electronic version of the journal
Licences: cc-by
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Sep-2025