| Issue |
A&A
Volume 694, February 2025
|
|
|---|---|---|
| Article Number | A257 | |
| Number of page(s) | 18 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361/202451818 | |
| Published online | 18 February 2025 | |
Observations of UX Ori in deep minima with the Nordic Optical Telescope
I. Analysis of spectral lines
1
Pulkovo Astronomical Observatory, Russian Academy of Sciences,
Pulkovskoe sh. 65,
St. Petersburg
196140,
Russia
2
Nordic Optical Telescope,
Rambla José Ana Fernández Pérez 7,
38711
Breña Baja,
Spain
3
Department of Physics and Astronomy, Aarhus University,
Munkegade 120,
8000
Aarhus C,
Denmark
4
Luleå University of Technology,
971 87
Luleå,
Sweden
5
SAAF, Svensk AmatörAstronomisk Förening,
Sweden
★ Corresponding author; lvtamb@mail.ru
Received:
6
August
2024
Accepted:
2
January
2025
Context. UX Orionis stars are the most active young stars; they undergo sporadic fadings of 2–4 magnitudes in the V-band, due to variable circumstellar extinction caused by a nearly edge-on star–disc system. The long-lasting monitoring of a number of stars of this type with the Nordic Optical Telescope from 2019 to 2024 has given a rich collection of material of high-resolution (R ∼ 25 000) spectra obtained during different brightness states of the stars. In this paper, we present the results of observations for UX Ori itself. Until now only one spectrum of high resolution had been obtained for this star during brightness minimum, making it difficult to do a comprehensive analysis.
Aims. Our aim is to analyse how different spectral lines change during such irregular fading events, when the star is going in and out of eclipses, obscured by dust along the line of sight.
Methods. For this purpose we provide a comparative analysis of the profiles and equivalent widths of the spectral lines belonging to the different atoms and ions. In addition we compare the results for UX Ori with those made for another target in our sample: RR Tau.
Results. Common features of variability are revealed: (1) a strengthening of the Hα line relatively to the continuum during eclipses; (2) the appearance of additional emission on the frequencies of photospheric lines (e.g. FeII, CaII, SiII). The different behaviour of the spectral lines during fading found for UX Ori and RR Tau may be caused by two effects: a different contribution of the scattered light to the stellar flux during eclipses or a less intense disc wind of UX Ori.
Key words: accretion, accretion disks / techniques: spectroscopic / stars: individual: UX Ori / stars: individual: RR Tau / stars: variables: T Tauri, Herbig Ae/Be / stars: winds, outflows
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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