Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars

Johansson, Sveneric; Letokhov, V. S.

doi:10.1051/0004-6361:20031613

Cited by 6 publications

(3 citation statements)

References 12 publications

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“…They all respond strongly to changes in the Lyα flux. This group includes permitted lines of Fe II, Fe III, Ni II, and Cr II, especially noteworthy are the famous Fe II lines, λλ2507 and 2509, demonstrated to be pumped by Lyα (Figure 4; Johansson & Letokhov 2003;and references therein). The intensities of Fe II λλ2507, 2509 increased about 2.5-fold in the eleven month interval between the 1998 and 1999 observations.…”

Section: Changes In Line Intensitiesmentioning

confidence: 99%

The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D

Verner

Bruhweiler

Gull

2005

ApJ

169

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We focus on two Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) spectra of the Weigelt Blobs B&D, extending from 1640 to 10400Å; one recorded during the 1998 minimum (March 1998) and the other recorded in February 1999, early in the following broad maximum. The spatially-resolved spectra suggest two distinct ionization regions. One structure is the permanently low ionization cores of the Weigelt Blobs, B&D, located several hundred AU from the ionizing source. Their spectra are dominated by emission from H I, [N II], Fe II, [Fe II], Ni II, [Ni II], Cr II and Ti II. The second region, relatively diffuse in character and located between the ionizing source and the Weigelt Blobs, is more highly ionized with emission from [Fe III]Through photoionization modeling, we find that the radiation field from the more massive B-star companion supports the low ionization structure throughout the 5.54 year period.The radiation field of an evolved O-star is required to produce the higher ionization emission seen across the broad maximum. This emission region is identified with slow-moving condensations photoionized by the O star and located in the extended mass flow emanating from the B star primary. Comparison between the models and observations reveals that the high ionization region is physically distinct (n H ≈ 10 7 cm -3 and T e ~ 10 4 K) from the BD Blobs (n H ≈

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Section: Changes In Line Intensitiesmentioning

confidence: 99%

The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D

Verner

Bruhweiler

Gull

2005

ApJ

169

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“…The most prominent nebular features from the Weigelt condensations during η Car's spectroscopic high-state are the H I Lyα-pumped fluorescent lines in Fe II, especially Fe II λλ2507, 2509 (Johansson & Letokhov 2003). Transitions from higher ionization stages, such as Fe 2+ , Fe 3+ , Ne 2+ , were also identified in the spectrum.…”

Section: The η Car Spectrummentioning

confidence: 94%

Eta Carinae Across the 2003.5 Minimum: Analysis in the Visible and Near-Infrared Spectral Region

Nielsen

Kober

Weis

et al. 2009

ApJS

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We present an analysis of the visible through near-infrared spectrum of Eta Carinae (η Car) and its ejecta obtained during the "η Car Campaign with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)." This is a part of larger effort to present a complete η Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 Å) to 10,430 Å. The spectrum in the mid-and near-UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow-emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 Å, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground-based seeing and contributions of nebular-scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 Å.

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“…One particular problem (Johansson & Letokhov 2003) was the understanding of why the kk2507, 2509 lines are so strong in the observed spectrum, and why they are of approximately equal strength. Verner et al (2002) found that if they abandoned the atomic data already published at that time and assumed a 50% mixing of the two upper levels of these transitions, their model did indeed agree with observation that these two lines are the strongest in the spectrum and of comparable intensity.…”

Section: Introductionmentioning

confidence: 99%

Oscillator Strengths of Near‐Infrared Lines of Feii

Correge

Hibbert

2006

ApJ

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Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars

Cited by 6 publications

References 12 publications

The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D

The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D

Eta Carinae Across the 2003.5 Minimum: Analysis in the Visible and Near-Infrared Spectral Region

Oscillator Strengths of Near‐Infrared Lines of Feii

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