J/A+A/669/A118 AD Leo spectral observations (Wollmann+, 2023)
Observations and modeling of spectral line asymmetries in stellar flares.
Wollmann J., Heinzel P., Kabath P.
<Astron. Astrophys. 669, A118 (2023)>
=2023A&A...669A.118W 2023A&A...669A.118W (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Stars, flare ; Spectra, optical
Keywords: stars: flares - stars: late-type - techniques: spectroscopic -
radiative transfer
Abstract:
Stellar flares are energetic events occurring in stellar atmospheres.
They have been observed on various stars using photometric light
curves and spectra. On some cool stars, flares tend to release
substantially more energy compared to solar flares. Spectroscopic
observations have revealed that some spectral lines, aside from an
enhancement and broadening, exhibit asymmetry in their profile.
Asymmetries with enhanced blue wings are often associated with the
presence of coronal mass ejections while the origin of the red
asymmetries is currently not well understood. A few mechanisms have
been suggested but no modeling has been performed yet.
We observed the dMe star AD Leo using the 2-meter Perek telescope at
Ondrejov observatory, with simultaneous photometric light curves. In
analogy with solar flares, we model the Hα line emergent from an
extensive arcade of cool flare loops and explain the observed
asymmetries using the concept of coronal rain.
We solve the non-LTE radiative transfer in Hα within cool flare
loops taking into account the velocity distribution of individual rain
clouds. For a flare occurring at the center of the stellar disc, we
then integrate radiation emergent from the whole arcade to get the
flux from the loop area.
We observed two flares in the Hα line that exhibit red wing
asymmetry corresponding to velocities up to 50km/s during the gradual
phase of the flare. Synthetic profiles generated from the model of
coronal rain have enhanced red wings quite compatible with
observations.
Description:
The fits files are spectral observations of AD Leo using Ondrejov
Echelle spectrograph (OES) on 2-meter Perek telescope in Ondrejov
observatory. The spectra are reduced and the flux units are ADU. Note
that you should apply barycentric correction to the spectra during
further processing.
Objects:
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RA (2000) DE Designation(s)
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10 19 36.28 +19 52 12.0 AD Leo = BD+20 2465
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 121 20 List of spectra
fits/* . 20 Individual fits spectra
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See also:
J/A+A/637/A13 : AD Leo high resolution spectra (Muheki+, 2020)
J/A+A/638/A5 : HD 285507 and AD Leo light and velocity curves (Carleo+, 2020)
J/A+A/666/A143 : AD Leo RV and stellar activity indices (Kossakowski+, 2022)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Nx Number of pixels along X-axis
8- 26 A19 "datime" Obs.date Observation date
28- 34 F7.2 0.1nm blambda Lower value of wavelength interval
36- 42 F7.2 0.1nm Blambda Upper value of wavelength interval
44- 52 F9.7 0.1nm dlambda Spectral resolution
54- 56 I3 Kibyte size Size of FITS file
58- 82 A25 --- FileName Name of FITS file, in subdirectory fits
84-121 A38 --- Title Title of the FITS file
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Acknowledgements:
Jiri Wollmann, wollmann.jirka(at)icloud.com
(End) Patricia Vannier [CDS] 18-Nov-2022