J/MNRAS/526/4885 Stable accretion of EX Lup and TW Hya (Sicilia-Aguilar+, 2023)
Stable accretion in young stars: The cases of EX Lupi and TW Hya.
Sicilia-Aguilar A., Campbell-White J., Roccatagliata V., Desira J.,
Gregory S.G., Scholz A., Fang M., Cruz-Saenz de Miera F., Kospal A.,
Matsumura S., Abraham P.
<Mon. Not. R. Astron. Soc. 526, 48854907 (2023)>
=2023MNRAS.526.4885S 2023MNRAS.526.4885S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry, SDSS ; Spectroscopy
Keywords: circumstellar matter - stars: individual: EX Lupi, TW Hya -
stars: pre-main-sequence - stars: variables: T Tauri, Herbig Ae/Be
Abstract:
We examine the long-term spectroscopic and photometric variability of
EX Lupi and TW Hya, studying the presence of stable accretion and the
role it plays in the observed variability. Analysing the velocity
modulations of the emission lines with STAR-MELT, we obtain
information on the structure of the accretion columns and the
disk-star connection. The emission line radial velocities reveal that
TW Hya, like EX Lupi, has a remarkably stable or slow-varying
accretion column footprint, locked to the star for several years. The
line-emitting regions are non-polar for both EX Lupi and TW Hya, and
species with different energies differ in position. In contrast, the
continuum emission as observed in the photometry is very variable and
can be modelled by hot spot(s) that change over time in phase, shape,
temperature, size, and location with respect to the emission line
region. The continuum emission region may not be limited to the
stellar surface, especially during episodes of high accretion. The
broad line emission observed in EX Lupi during episodes of increased
accretion reveals a further structure, which can be fitted by
non-axisymmetric disk in Keplerian rotation inwards of the corotation
radius. Since the radial velocity modulation due to accretion
footprints is so stable, we used it to search for further velocity
modulations. While no residual modulation (other than caused by
stellar rotation) is found in these objects, a similar analysis could
help to identify young planets/companions. Therefore, determining
whether stable accretion footprints are common among young stars is a
key to detect young planets.
Description:
We examine how time-resolved spectroscopy and multiband photometry
unveil the structure of the accretion process in young stars,
using EX Lupi and TW Hya as test benches.
Tables accompanying the published article. Include the full list of
emission lines identified in TW Hya (Table 1), and the appendix tables
with the list of available spectral observations (Table A1) and the
relative photometry from the Las Cumbres Observatory Global Telescope
Network (LCOGT, Table A2).
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
16 03 05.49 -40 18 25.4 EX Lupi = V* EX Lup
11 01 51.90 -34 42 17.0 TW Hya = V* TW Hya
-------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 106 109 Lines detected by STAR-MELT in the spectra of
TW Hya
tablea1.dat 43 645 Spectra used in this paper
tablea2.dat 28 328 EX Lup LCOGT relative magnitudes and MJD
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See also:
J/A+A/607/A127 : 2014-2017 photometry for ASASSN-13db (Sicilia-Aguilar+, 2017)
J/A+A/643/A29 : Z CMa NW emission lines (Sicilia-Aguilar+, 2020)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Species Atomic species
4- 5 A2 --- Ion Ionization state
7- 14 F8.2 0.1nm lambda Laboratory Wavelength (Air) (1)
17- 31 F15.5 s-1 Aki ? Transition probability (1)
34- 39 F6.3 eV Ek Energy of the upper level, k (1)
41- 46 F6.3 eV Ei Energy of the lower level, i (1)
48-106 A59 --- Notes Notes on previous detections of the line
--------------------------------------------------------------------------------
Note (1): Information on the laboratory wavelength (in air), transition
probability and energies of the lower and upper level (from the NIST Database;
Kramida et al., 2010APS..DMP.E1032K), as well as on observations of the line
in other stars (EX Lupi, ZCMa, and ASASSN-13db, see Sicilia-Aguilar et al.,
2012A&A...544A..93S 2012A&A...544A..93S, 2015A&A...580A..82S 2015A&A...580A..82S, 2017A&A...607A.127S 2017A&A...607A.127S,
2020A&A...643A..29S 2020A&A...643A..29S, Campbell-White et al. 2021MNRAS.507.3331C 2021MNRAS.507.3331C) is also
provided.
E12o- identified in Sicilia-Aguilar et al. 2012A&A...544A..93S 2012A&A...544A..93S
for EX Lup in outburst
E12q- identified in Sicilia-Aguilar et al. 2012A&A...544A..93S 2012A&A...544A..93S
for EX Lup in quiescence
E15q- identified in Sicilia-Aguilar et al. 2015A&A...580A..82S 2015A&A...580A..82S
for EX Lup in quiescence
A17o- identified in Sicilia-Aguilar et al. 2017A&A...607A.127S 2017A&A...607A.127S
for ASASSN-13db in outburst
Z20o- identified in Sicilia-Aguilar et al. 2020A&A...643A..29S 2020A&A...643A..29S
for ZCMa in outburst
Z20q- identified in Sicilia-Aguilar et al. 2020A&A...643A..29S 2020A&A...643A..29S
for ZCMa in quiescence
In case where the identification is not unique, all possibilities are
given.
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- Object Name of the object (EX Lup or TW Hya)
8- 19 F12.6 d MJD Modified Julian date of observation (1)
21- 28 A8 --- Inst Spectroscop used for observations (1)
30- 35 F6.2 0.1nm b_lambda Minimum wavelength covered (1)
37- 43 F7.2 0.1nm B_lambda Maximum wavelength covered (1)
--------------------------------------------------------------------------------
Note (1): All the data are available via the ESO and CFHT archives.
Note that for EX Lup we only analyse observations where the broad components
were detected, and excluded the 2008 eruption data.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- Filter [up gp rp ip] Name of LCOGT filter
4- 15 F12.6 d MJD Modified Julian date of observation
17- 22 F6.3 mag mag Relative magnitude in Filter (1)
24- 28 F5.3 mag e_mag ?=- Uncertainty in the relative magnitude
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Note (1): All magnitudes given with respect to the mean in each filter.
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History:
From Aurora Sicilia-Aguilar, asiciliaaguilar(at)dundee.ac.uk
Acknowledgements:
STFC grant number ST/S000399/1 ("The Planet-Disk Connection:
Accretion, Disk Structure, and Planet Formation")
References:
Campbell-White et al., 2021MNRAS.507.3331C 2021MNRAS.507.3331C
The STAR-MELT PYTHON package for emission-line analysis of YSOs
Kramida et al., , 2010APS..DMP.E1032K
Atomic Spectra Bibliography Databases at NIST
Sicilia-Aguilar et al., 2012A&A...544A..93S 2012A&A...544A..93S
Optical spectroscopy of EX Lupi during quiescence and outburst.
Infall, wind, and dynamics in the accretion flow
Sicilia-Aguilar et al., 2015A&A...580A..82S 2015A&A...580A..82S
Accretion dynamics of EX Lupi in quiescence. The star, the spot, and the
accretion column
Sicilia-Aguilar et al., 2017A&A...607A.127S 2017A&A...607A.127S, Cat. J/A+A/607/A127
The 2014-2017 outburst of the young star ASASSN-13db. A time-resolved
picture of a very-low-mass star between EXors and FUors
Sicilia-Aguilar et al., 2020A&A...643A..29S 2020A&A...643A..29S, Cat. J/A+A/643/A29
Reading between the lines. Disk emission, wind, and accretion during the
Z CMa NW outburst
(End) Patricia Vannier [CDS] 24-Oct-2023