Star-disk interaction in the T Tauri star V2129 Ophiuchi: An evolving accretion-ejection structure

Sousa, A. P.; Bouvier, J.; Alencar, S. H. P.; Donati, J.‐F.; Alécian, E.; Roquette, J.; Perraut, K.; Dougados, C.; Covino, S.; Fugazza, D.; Molinari, E.; Moutou, C.; Santerne, A.; Grankin, K. N.; Artigau, Étienne; Delfosse, X.; Hébrard, G.

doi:10.1051/0004-6361/202140346

Cited by 15 publications

(10 citation statements)

References 93 publications

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“…We also show the averaged veiling obtained for each target in Table 2. The veiling values increase from the Y to the K band for most of the targets, similar to the results found in previous works (e.g., Mc-Clure et al 2013;Sousa et al 2021;Alcalá et al 2021). Besides this general result, the average veiling for some individual targets remains the same from the Y to K band.…”

Section: Resultssupporting

confidence: 90%

New insights on the near-infrared veiling of young stars using CFHT/SPIRou data

Sousa¹,

Bouvier²,

Alencar³

et al. 2023

Preprint

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Context.Veiling is ubiquitous at different wavelength ranges in classical T Tauri stars. However, the origin of the veiling in the infrared (IR) domain is not well understood at present. The accretion spot alone is not enough to explain the shallow photospheric IR lines in accreting systems, suggesting that another source is contributing to the veiling in the near-infrared (NIR). The inner disk is often quoted as the additional emitting source meant to explain the IR veiling. Aims. In this work, we aim to measure and discuss the NIR veiling to understand its origins and variability timescale. Methods. We used a sample of 14 accreting stars observed with the CFHT/SPIRou spectrograph, within the framework of the SPIRou Legacy Survey, to measure the NIR veiling along the Y JHK bands. We compared the veiling measurements with accretion and inner disk diagnostics. We also analyzed circumstellar emission lines and photometric observations from the literature. Results. The measured veiling grows from the Y to the K band for most of the targets in our sample. The IR veiling agrees with NIR emission excess obtained using photometric data. However, we also find a linear correlation between the veiling and the accretion properties of the system, showing that accretion contributes to the inner disk heating and, consequently, to the inner disk emission excess. We also show a connection between the NIR veiling and the system's inclination with respect to our line of sight. This is probably due to the reduction of the visible part of the inner disk edge, where the NIR emission excess is expected to arise, as the inclination of the system increases. Our search for periods on the veiling variability showed that the IR veiling is not clearly periodic in the typical timescale of stellar rotation -which, again, is broadly consistent with the idea that the veiling comes from the inner disk region. The NIR veiling appears variable on a timescale of a day, showing the night-by-night dynamics of the optical veiling variability. In the long term, the mean NIR veiling seems to be stable for most of the targets on timescales of a month to a few years. However, during occasional episodes of high accretion in classical T Tauri stars, which affect the system's dynamic, the veiling also seems to be much more prominent at such times, as we found in the case of the target RU Lup. Conclusions. We provide further evidence that for most targets in our sample, the veiling that mainly occurs in the JHK bands arises from dust in the inner disk.

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Section: Resultssupporting

confidence: 90%

New insights on the near-infrared veiling of young stars using CFHT/SPIRou data

Sousa¹,

Bouvier²,

Alencar³

et al. 2023

Preprint

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“…In order to further investigate the putative modulation at 8.33 d unveiled from the chromospheric indices, we compute the bidimensional periodogram of each emission line to quantify the evolution of the flux variability across the line profile, as it is commonly done for young PMS stars (e.g., Johns & Basri 1995;Bouvier et al 2007;Sousa et al 2021;Finociety et al 2021). We first normalize the continuum of each chromospheric line from the blaze-subtracted HARPS spectra in the stellar rest frame.…”

Section: Bidimensional Periodogram Analysismentioning

confidence: 99%

One year of AU Mic with HARPS – II. Stellar activity and star–planet interaction

Klein

Zicher

Kavanagh

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a spectroscopic analysis of a 1-year intensive monitoring campaign of the 22-Myr old planet-hosting M dwarf AU Mic using the HARPS spectrograph. In a companion paper, we reported detections of the planet radial velocity (RV) signatures of the two close-in transiting planets of the system, with respective semi-amplitudes of 5.8 ± 2.5 m s−1 and 8.5 ± 2.5 m s−1 for AU Mic b and AU Mic c. Here, we perform an independent measurement of the RV semi-amplitude of AU Mic c using Doppler imaging to simultaneously model the activity-induced distortions and the planet-induced shifts in the line profiles. The resulting semi-amplitude of 13.3 ± 4.1 m s−1 for AU Mic c reinforces the idea that the planet features a surprisingly large inner density, in tension with current standard models of core accretion. Our brightness maps feature significantly higher spot coverage and lower level of differential rotation than the brightness maps obtained in late 2019 with the SPIRou spectropolarimeter, suggesting that the stellar magnetic activity has evolved dramatically over a ∼1-yr time span. Additionally, we report a 3-σ detection of a modulation at 8.33 ± 0.04 d of the He I D3 (5875.62 Å) emission flux, close to the 8.46-d orbital period of AU Mic b. The power of this emission (a few 1017 W) is consistent with 3D magnetohydrodynamical simulations of the interaction between stellar wind and the close-in planet if the latter hosts a magnetic field of ∼10 G. Spectropolarimetric observations of the star are needed to firmly elucidate the origin of the observed chromospheric variability.

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“…(2021) compared their results with the periodograms for the same system as was analyzed by Alencar et al (2012), and they found some differences on timescales of a decade, similarly to our results. Sousa et al (2021) discussed a few possible explanations for the observed phenomena, such as variations in the magnetic field strength, which would result in variations in the magnetospheric truncation radius, or latitudinal differential rotation, or a more complex magnetic structure with two major funnel flows originating at different radii in the inner disk. However, in the case of V2129 Oph, a periodicity longer than the stellar rotation period is present at the line center for a time of almost a decade.…”

Section: Line Morphology Variationsmentioning

confidence: 99%

Accretion variability from minute to decade timescales in the classical T Tauri star CR Cha

Zsidi

Manara

Kóspál

et al. 2022

A&A

Self Cite

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Context. Classical T Tauri stars are pre-main-sequence stars that are surrounded by a circumstellar disk from which they accrete material. The mass accretion process is essential in the formation of Sun-like stars. Although often described with simple and static models, the accretion process is inherently time variable. Aims. We examine the accretion process of the low-mass young stellar object CR Cha on a wide range of timescales from minutes to a decade by analyzing both photometric and spectroscopic observations from 2006, 2018, and 2019. Methods. We carried out a period analysis of the light curves of CR Cha from the TESS mission and the ASAS-SN and the ASAS-3 databases. We studied the color variations of the system using I, J, H, K-band photometry obtained contemporaneously with the TESS observing window. We analyzed the amplitude, timescale, and the morphology of the accretion tracers found in a series of high-resolution spectra obtained in 2006 with the AAT/UCLES, in 2018 with the HARPS, and in 2019 with the ESPRESSO and the FEROS spectrographs. Results. All photometric data reveal periodic variations compatible with a 2.327-day rotational period. In addition, the ASAS-SN and ASAS-3 data indicate a long-term brightening by 0.2 mag between 2001 and 2008, and a slightly lower brightening than 0.1 mag in the 2015–2018 period. The near-infrared photometry indicates a short-term brightening trend during the observations in 2019. The corresponding color variations can be explained either by a changing accretion rate or changes in the inner disk structure. The Hα line profile variability suggests that the amplitude variations of the central peak, likely due to accretion, are most significant on daily or hourly timescales. On yearly timescales, the line morphology also changes significantly. Conclusions. The photometric variability shows that the period of about 2.3 days is stable in the system over decades. Our results show that the amplitude of the variations in the Hα emission increases on timescales from hours to days or weeks, after which it remains similar even at decadal timescales. On the other hand, we found significant morphological variations on yearly or decadal timescales, indicating that the different physical mechanisms responsible for the line profile changes, such as accretion or wind, are present to varying degrees at different times.

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Star-disk interaction in the T Tauri star V2129 Ophiuchi: An evolving accretion-ejection structure

Cited by 15 publications

References 93 publications

New insights on the near-infrared veiling of young stars using CFHT/SPIRou data

New insights on the near-infrared veiling of young stars using CFHT/SPIRou data

One year of AU Mic with HARPS – II. Stellar activity and star–planet interaction

Accretion variability from minute to decade timescales in the classical T Tauri star CR Cha

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