J/A+A/578/A122 eta Carinae's 2014.6 spectroscopic event (Mehner+, 2015)
Eta Carinae's 2014.6 spectroscopic event:
Clues to the long-term recovery from its Great Eruption.
Mehner A., Davidson K., Humphreys R.M., Walter F.M., Baade D., de Wit W.J.,
Martin J., Ishibashi K., Rivinius T., Martayan C., Ruiz M.T., Weis K.
<Astron. Astrophys., 578, A122-122 (2015)>
=2015A&A...578A.122M 2015A&A...578A.122M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Equivalent widths
Keywords: stars: massive - stars: variables: S Doradus -
stars: individual: eta Carinae - stars: winds, outflows -
stars: mass-loss
Abstract:
Every 5.5-years, η Car's light curve and spectrum change
remarkably across all observed wavelength bands. These so-called
spectroscopic events are most likely caused by the close approach of a
companion. We compare the recent spectroscopic event in mid-2014 to
the events in 2003 and 2009 and investigate long-term trends.
Eta Car was observed with HST STIS, VLT UVES, and CTIO 1.5m CHIRON for
a period of more than two years in 2012-2015. Archival observations
with these instruments cover three orbital cycles and the events of
2003.5, 2009.1, and 2014.6. The STIS spectra provide high spatial
resolution and include epochs during the 2014 event when observations
from most ground-based observatories were not feasible. The strategy
for UVES observations allows for a multidimensional analysis, because
each location in the reflection nebula is correlated with a different
stellar latitude.
Important spectroscopic diagnostics during η Car's events show
significant changes in 2014 compared to previous events. While the
timing of the first HeII λ4686 flash was remarkably similar to
previous events, the HeII equivalent widths were slightly larger, and
the line flux increased by a factor of ∼7 compared to 2003. The second
HeII peak occurred at about the same phase as in 2009, but was
stronger. The HeI line flux grew by a factor of ∼8 in 2009-2014
compared to 1998-2003. The NII emission lines also increased in
strength. On the other hand, Hα and FeII lines show the smallest
emission strengths ever observed in η Car. The optical continuum
brightened by a factor of ∼4 in the past 10-15 years. The polar
spectrum shows fewer changes in the broad wind emission lines: the
FeII emission strength decreased by a factor of ∼2 (compared to a
factor of ∼4 in our direct line of sight). The HeII equivalent widths
at FOS4 were larger in 2009 and 2014 than during the 2003 event.
Description:
We report on new Hubble Space Telescope Space Telescope Imaging
Spectrograph (HST STIS) spectra obtained during the 2014 event.
Objects:
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RA (2000) DE Designation(s)
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10 45 03.55 -59 41 04.0 eta Car = HR 4210
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 109 Journal of observations
table2.dat 62 132 HeII equivalent width and velocity in direct
view of the star
table3.dat 62 75 HeII equivalent width and velocity at FOS4
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See also:
J/ApJS/71/983 : UV spectrum of eta Car (Viotti+ 1989)
J/A+A/304/415 : uvby-Hbeta photometry of eta Car 1992-94 (van Genderen+, 1995)
J/A+A/343/847 : Geneva Photometry of eta Car (van Genderen+ 1999)
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/ApJS/181/473 : Analysis of the spectrum of eta Car (Nielsen+, 2009)
J/A+A/493/1093 : BVRI light curves of eta Car (Fernandez-Lajus+, 2009)
J/other/NewA/15.108 : UBVRIHα of eta Car in 2009 (Fernandez-Lajus+ 2010)
J/A+A/540/A133 : eta Car emission spectrum (1700-10400Å) (Zethson+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Inst Instrument
10- 13 A4 --- Pos Position (Star or FOS4)
15- 24 A10 "date" Date Observation date
26- 32 D7.1 d MJD Modified Julian date of observation
34- 38 F5.3 --- Phase Phase
40- 48 A9 --- Wave Wavelength interval or code for
wavelength interval (in Å) (1)
50-102 A53 --- ExpTime Exposure time(s) (in s) (2)
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Note (1): Code for wavelength interval:
DIC1 = 3044-3916, 4726-5803, 5762-6835
DIC2 = 3732-4999, 6649-8544, 8523-10426
Note (2): STIS/CCD slit: 52"x0.1".
UVES slit widths: 0.4" (blue arm) and 0.3" (red arm).
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Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Pos Position (Star or FOS4)
6- 13 A8 --- Inst Instrument
15- 24 A10 "date" Date Observation date
26- 32 F7.1 d MJD Modified Julian date of observation
34- 38 F5.3 --- Phase Phase
40- 46 F7.4 0.1nm mEW Opposit of HeII equivalent width (-EW)
48- 52 F5.3 0.1nm e_mEW rms uncertainty on EW
54- 58 I5 km/s Vel ? Peak velocity (1)
60- 62 I3 km/s e_Vel ? rms uncertainty on Vel
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Note (1): Peak velocity corrected for the moving-mirror effect for FOS4 (table3)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Sep-2015