J/A+A/643/A29 Z CMa NW emission lines (Sicilia-Aguilar+, 2020)
Reading between the lines.
Disk emission, wind, and accretion during the Z CMa NW outburst.
Sicilia-Aguilar A., Bouvier J., Dougados C., Grankin K., Donati J.-F.
<Astron. Astrophys. 643, A29 (2020)>
=2020A&A...643A..29S 2020A&A...643A..29S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Stars, pre-main sequence ; Spectroscopy
Keywords: stars: pre-main sequence - stars: variables: T Tauri, Herbig AeBe -
stars: individual: Z CMa NW - protoplanetary disks -
accretion, accretion disks - techniques: spectroscopic
Abstract:
We use optical spectroscopy to investigate the disk, wind, and
accretion during the 2008 Z CMa NW outburst.
The emission lines are used to constrain the locations, densities, and
temperatures of the structures around the star.
Over 1000 optical emission lines reveal accretion, a variable,
multi-component wind, and double-peaked lines of disk origin. The
variable, non-axisymmetric, accretion-powered wind has slow (∼0km/s ),
intermediate (~-100km/s) and fast (≥-400km/s) components. The fast
components are of stellar origin and disappear in quiescence, while
the slow component is less variable and could be related to a disk
wind. The changes in the optical depth of the lines between outburst
and quiescence are consistent with increased accretion being
responsible for the observed outburst. We derive an accretion rate of
10-4M☉/yr in outburst. The FeI and weak FeII lines arise from
an irradiated, flared disk at ∼0.5-3(M*/16M☉) au with asymmetric
upper layers, revealing that the energy from the accretion burst is
deposited at scales below 0.5au. Some line profiles have redshifted
asymmetries, but the system is unlikely sustained by magnetospheric
accretion, especially in outburst. The accretion-related structures
extend over several stellar radii and, like the wind, are likely
non-axisymmetric. The stellar mass may be ∼6-8M☉, lower
than previously thought (∼16M☉).
Emission line analysis is found to be a powerful tool to study the
innermost regions and accretion in stars within a very large range of
effective temperatures. The density ranges in the disk and accretion
structures are higher than in late-type stars, but the overall
behavior, including the innermost disk emission and variable wind, is
very similar independently of the spectral type. Our work suggests a
common outburst behavior for stars with spectral types ranging from
M-type to intermediate-mass stars.
Description:
Emission lines observed during outburst and quiescence.
The lines are classified as "double-peaked" or disk-like (Dsk),
"PCygni profiles" (PC). Those with complex, multi-component wind
absorption signatures are marked as "PC+". Potential blends and
contamination by atmospheric features are marked by "Bl" and "Atm",
respectively. Those that could not be classified are labeled as
"INDEF", and in some cases, a potential identification is given in the
notes. The wavelengths provided are laboratory measurements (air),
except for non-identified lines for which we list the observed
wavelengths. If the line is not seen, it is marked as "N", except if
this part of the spectrum was not covered or if other features may
have difficulted the identification, in which case we mark it as "-".
Lines marked with vdA04 have been observed by van den Ancker et al.
(2004MNRAS.349.1516V 2004MNRAS.349.1516V) during the 1999 outburst. Lines marked with WS
have been identified using Wahlgren & Shore list (S. Shore, private
communication), while the rest have been identified with the NIST
database. Lines that are potentially pumped by other UV lines (from
Herczeg et al., 2005AJ....129.2777H 2005AJ....129.2777H) are marked accordingly. For some
of the close blends without clear peaks, the species cannot be easily
identified. Note that the quiescence data had a lower spectral
coverage, ending around 6940Å.
Objects:
-----------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------
07 03 43.16 -11 33 06.2 Z CMa = V* Z CMa
-----------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 136 497 Emission lines observed during outburst
and quiescence
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Species Species
19- 27 F9.3 0.1nm lambda-air Wavelength, or
lower value of wavelength interval
28 A1 --- --- [-/]
29- 37 F9.3 0.1nm lambda-air2 ? Upper value of wavelength interval
38- 52 F15.5 --- Aki ? Transition probability Aki
53 A1 --- --- [/]
54- 61 F8.6 --- Aki2 ? Second value of Aki
63- 68 F6.3 --- Ei ? Energy of the lower level
70- 75 F6.3 --- Ek ? Energy of the upper level
77- 78 A2 --- Outburst [NY-: ] Observed in outburst?
(Y - yes, N - no, - no data)
80 A1 --- Quiescence [-NY] Observed in quiescence?
(Y - yes, N - no, - no data)
82- 88 A7 --- Type Line type (1)
90-136 A47 --- Notes Notes and references (2)
--------------------------------------------------------------------------------
Note (1): Line type as follows:
Wk = weak
PC = P Cygni
PC+ = PC with very strong absorption
Bl = blend
Dsk = disk-like profile
Atm = contaminated by atmospheric features
Note (2): References:
vdA04 = line observed by van den Ancker et al. (2004MNRAS.349.1516V 2004MNRAS.349.1516V) during
the 1999 outburst
WS = line identified using Wahlgren & Shore list
(S. Shore, private communication)
--------------------------------------------------------------------------------
Acknowledgements:
Aurora Sicilia-Aguilar, asiciliaaguilar(at)dundee.ac.uk
(End) Patricia Vannier [CDS] 02-Sep-2020