J/A+A/672/A5 GM Aur LCOGT urgi light curves (Bouvier+, 2023)
Stable accretion and episodic outflows in the young transition disk system
GM Aurigae. A semester-long optical and near-infrared spectrophotometric
monitoring campaign.
Bouvier J., Sousa S, Pouilly K., Almenara J.M., Donati J.-F.,
Alencar S.H.P., Frasca A., Grankin K., Carmona A., Pantolmos G., Zaire B.,
Bonfils X., Bayo A., Rebull L.M., Alonso-Santiago J., Gameiro J.F.,
Cook N.J., Artigau E. (the Spirou Legacy Survey (SLS) consortium)
<Astron. Astrophys. 672, A5 (2023)>
=2023A&A...672A...5B 2023A&A...672A...5B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Photometry ; Optical
Keywords: accretion, accretion disks - stars: magnetic field -
stars: individual: GM Aur - stars: pre-main sequence -
stars: variables: T Tauri, Herbig Ae/Be - stars: winds, outflows
Abstract:
Young stellar systems actively accrete from their circumstellar disk
and simultaneously launch outflows. The physical link between
accretion and ejection processes remains to be fully understood.
We investigate the structure and dynamics of magnetospheric accretion
and associated outflows on a scale smaller than 0.1au around the young
transitional disk system GM Aur.
We devised a coordinated observing campaign to monitor the variability
of the system on timescales ranging from days to months, including
partly simultaneous high-resolution optical and near-infrared
spectroscopy, multiwavelength photometry, and low-resolution
near-infrared spectroscopy, over a total duration of six months,
covering 30 rotational cycles. We analyzed the photometric and line
profile variability to characterize the accretion and ejection
processes.
The optical and near-infrared light curves indicate that the
luminosity of the system is modulated by surface spots at the stellar
rotation period of 6.04±0.15-days. Part of the Balmer, Paschen, and
Brackett hydrogen line profiles as well as the HeI 5876Å and HeI
10830Å line profiles are modulated on the same period. The Paβ
line flux correlates with the photometric excess in the u' band, which
suggests that most of the line emission originates from the accretion
process. High-velocity redshifted absorptions reaching below the
continuum periodically appear in the near-infrared line profiles at
the rotational phase in which the veiling and line fluxes are the
largest. These are signatures of a stable accretion funnel flow and
associated accretion shock at the stellar surface. This large-scale
magnetospheric accretion structure appears fairly stable over at least
15 and possibly up to 30 rotational periods. In contrast, outflow
signatures randomly appear as blueshifted absorption components in the
Balmer and HeI 10830Å line profiles. They are not rotationally
modulated and disappear on a timescale of a few days. The coexistence
of a stable, large-scale accretion pattern and episodic outflows
supports magnetospheric ejections as the main process occurring at the
star-disk interface.
Long-term monitoring of the variability of the GM Aur transitional
disk system provides clues to the accretion and ejection structure and
dynamics close to the star. Stable magnetospheric accretion and
episodic outflows appear to be physically linked on a scale of a few
stellar radii, mimicking at the sub-au scale the commonly acknowledged
relationship between disk accretion and disk winds on a much larger
scale.
Description:
LCOGT photometry of GM Aur.
Objects:
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RA (2000) DE Designation(s)
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04 55 10.98 +30 21 59.3 GM Aur = SV* SVS 1089
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
umag.dat 65 131 GM Aur LCOGT u' photometry
gmag.dat 67 241 GM Aur LCOGT g' photometry
rmag.dat 67 240 GM Aur LCOGT r' photometry
imag.dat 67 238 GM Aur LCOGT i' photometry
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Byte-by-byte Description of file: gmag.dat imag.dat rmag.dat umag.dat
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Bytes Format Units Label Explanations
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1 A1 --- Band [ugri]
3- 20 F18.10 d JD Julian date
24- 41 F18.15 mag mag Magnitude in Band
45- 65 F21.19 mag e_mag rms uncertainty on mag
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Acknowledgements:
Jerome Bouvier, jerome.bouvier(at)univ-grenoble-alpes.fr
(End) Patricia Vannier [CDS] 27-Jan-2023