Dicke Narrowing, Pressure Dependence, and Mixing of Self-Broadened CO2 Absorption Lines in the 30013 ← 00001 Band: Measurements and Line Profile Testing

I am reporting here work done recently by the astrophysics group at the University of Queensland (notably G. D. Finn and R. L. Young). We are interested in the detailed formation of the profiles of the sodium-D solar absorption lines. These lines are very strong with extended wings and the object of the exercise is to determine how closely, under the physical conditions assumed to exist in the solar atmosphere, we can theoretically reproduce the detailed line profile which is observed.

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Non-radial Pulsation Modeling of ω (28) CMa

International Astronomical Union Colloquium ◽

10.1017/s0252921100055925 ◽

2000 ◽

Vol 175 ◽

pp. 244-247 ◽

Cited By ~ 6

Author(s):

M. Maintz ◽

Th. Rivinius ◽

S. Tubbesing ◽

B. Wolf ◽

S. Štefl ◽

...

Keyword(s):

Velocity Field ◽

Line Profile ◽

Inertial Frame ◽

Absorption Lines ◽

Pulsation Period ◽

Radial Pulsation ◽

Line Profiles ◽

Stellar Rotation ◽

Velocity Effect

AbstractAdopting non-radial pulsation (nrp) the line profile variability lpv of several absorption lines of different ions was modeled for ω (28) CMa. The parameters suggested by Baade (1982) to characterise the pulsation could be confirmed. The pulsation period in the inertial frame was found to be negative, i.e. an actually retrograde mode appears prograde due to the rapid stellar rotation. The line profiles could be reproduced in detail including structures like spikes and ramps. They were identified as velocity effect due to the latitudinal component of the nrp velocity field υϑ in combination with low inclination i. In spite of small photometric variations (Štefl et al. 1999) the lpv of the absorption lines can be explained by nrp entirely.

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Vertical wind profiling from troposphere to the lower mesosphere based on high resolution heterodyne near-infrared spectroradiometry

10.5194/amt-2019-444 ◽

2019 ◽

Author(s):

Alexander V. Rodin ◽

Dmitry V. Churbanov ◽

Sergei G. Zenevich ◽

Artem Yu. Klimchuk ◽

Vladimir M. Semenov ◽

...

Keyword(s):

Absorption Line ◽

Line Profile ◽

Spectral Resolution ◽

Near Infrared ◽

Signal To Noise Ratio ◽

Rotational Line ◽

Co2 Absorption ◽

Signal To Noise ◽

Overtone Band ◽

Noise Ratio

Abstract. We propose a new technique of remote wind measurements based on Doppler analysis of a CO2 absorption line in the 1.605 μm overtone band measured in the direct Sun observation geometry. Heterodyne spectroradiometric measurements of the solar radiation passed through the atmosphere provides an unprecedented spectral resolution up to λ/δλ ~ 107–108 with a signal-to-noise ratio more than 100. The shape of the individual rotational line profile provides unambiguous relationship between offset from the line centre and altitude where a respective part of the line profile is formed. Therefore, an inverse problem may be posed in order to retrieve vertical distribution of wind, with retrievals vertical resolution compromised by a spectral resolution and signal-to-noise ratio of the measurements. A close coincidence between measured and synthetic absorption line is reached, with retrieved wind profile between the surface and 50 km being in a good agreement with reanalysis models. This method may pose an alternative to widely employed lidar and radar techniques.

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Is λ Cep a pulsating star?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314006863 ◽

2014 ◽

Vol 9 (S307) ◽

pp. 237-238

Author(s):

J.M. Uuh-Sonda ◽

P. Eenens ◽

G. Rauw

Keyword(s):

Absorption Line ◽

Line Profile ◽

Stellar Surface ◽

Absorption Lines ◽

Full Dataset ◽

Rotating Star ◽

Radial Pulsations

AbstractIt has been proposed that the variability seen in absorption lines of the O6Ief star λ Cep is periodical and due to non-radial pulsations (NRP). We have obtained new spectra during six campaigns lasting between five and nine nights. In some datasets we find recurrent spectral variations which move redward in the absorption line profile, consistent with perturbations on the stellar surface of a rotating star. However the periods found are not stable between datasets, at odds with the NRP hypothesis. Moreover, even when no redward trend is found in a full dataset of an observing campaign, it can be present in a subset, suggesting that the phenomenon is short-lived, of the order of a few days, and possibly linked to transient magnetic loops.

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Two Modes of Pulsation in the Rapidly Rotating O9.5 Dwarf, HD 93521

International Astronomical Union Colloquium ◽

10.1017/s0252921100037246 ◽

1995 ◽

Vol 155 ◽

pp. 309-310

Author(s):

A.H.N. Reid ◽

D. Bohlender ◽

C.T. Bolton ◽

A.W. Fullerton ◽

I.D. Howarth ◽

...

Keyword(s):

Time Series ◽

Time Series Analysis ◽

Line Profile ◽

Absorption Lines ◽

Radial Pulsation ◽

Preliminary Results ◽

Series Analysis ◽

The Continuum

AbstractWe present preliminary results of a time-series analysis on the He II λ4541Å, Si III λλ4552, 4567, 4575Å and Hβ λ486lÅ lines of the late O-type dwarf, HD 93521. The spectra show line-profile variations (lpv) − ‘bumps’ and ‘dips’ − of amplitude ∼ 1% of the continuum, moving systematically redwards through the photospheric absorption lines. The analysis implies non-radial pulsation (NRP) as the origin for the lpv.

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Vertical wind profiling from the troposphere to the lower mesosphere based on high-resolution heterodyne near-infrared spectroradiometry

Atmospheric Measurement Techniques ◽

10.5194/amt-13-2299-2020 ◽

2020 ◽

Vol 13 (5) ◽

pp. 2299-2308 ◽

Cited By ~ 2

Author(s):

Alexander V. Rodin ◽

Dmitry V. Churbanov ◽

Sergei G. Zenevich ◽

Artem Y. Klimchuk ◽

Vladimir M. Semenov ◽

...

Keyword(s):

Absorption Line ◽

Line Profile ◽

Spectral Resolution ◽

Near Infrared ◽

Signal To Noise Ratio ◽

Line Center ◽

Rotational Line ◽

Co2 Absorption ◽

Signal To Noise ◽

Noise Ratio

Abstract. We propose a new technique of remote wind measurements based on Doppler analysis of a CO2 absorption line in the 1.605 µm overtone band measured in the direct Sun observation geometry. Heterodyne spectroradiometric measurements of the solar radiation passing through the atmosphere provide an unprecedented spectral resolution up to λ/δλ∼6×107, with a signal-to-noise ratio of more than 100. The shape of the individual rotational line profile provides an unambiguous relationship between the offset from the line center and the altitude at which the respective part of the line profile is formed. Therefore, an inverse problem may be posed in order to retrieve the vertical distribution of wind because with retrievals the vertical resolution is compromised by a spectral resolution and the signal-to-noise ratio of the measurements. A close coincidence between the measured and synthetic absorption line is reached, with retrieved wind profiles between the surface and 50 km being in good agreement with reanalysis models. This method may pose an alternative to widely employed lidar and radar techniques.

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