J/A+A/699/A82 The birth of Be star disks. I. (Labadie-Bartz+, 2025)
The birth of Be star disks. I. From localized ejection to circularization.
Labadie-Bartz J., Carciofi A.C., Rubio A.C., Baade D., Siverd R., Arcos C.,
Figueiredo A.L., Naze Y., Neiner C., Rivinius T., Richardson N.D., Nova S.,
Pinho M.L., Bhattacharyya S., Leadbeater R., Guarro Flo J., Lecocq V.,
Piehler G., Kozok J., Sollecchia U., Bryssinck E., Buil C., Martin J.,
Desnoux V., Heathcote B., Cacella P., Bertrand G., Broussat J.J.,
Ventura A., Diz R., Blais A., Somogyi P., Thizy O., Garde O., Charbonnel S.,
Le Du P., Mulato L., Petit T.
<Astron. Astrophys. 699, A82 (2025)>
=2025A&A...699A..82L 2025A&A...699A..82L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Spectroscopy ; Photometry ; Mass loss
Keywords: techniques: spectroscopic - techniques: photometric -
stars: circumstellar matter - stars: emission-line, Be -
stars: oscillations - stars: winds, outflows
Abstract:
Classical Be stars are well known to eject mass to build up a disk,
but the details governing the initial distribution and subsequent
evolution of this matter into a disk are in general poorly constrained
through observations. By combining high-cadence time-series
spectroscopy with contemporaneous space photometry from the Transiting
Exoplanet Survey Satellite (TESS), we have sampled about 30 mass
ejection events in 13 Be stars. Our goal is to constrain the
geometrical and kinematic properties of the ejecta as early as
possible, facilitating the investigation into the material's initial
conditions and evolution, and understanding its interactions with
preexisting material. The photometric variability is analyzed together
with measurements of the at-times rapidly changing emission features
in order to identify the onset of outburst events and obtain
information about the geometry of the ejecta and how it changes over
time. Short-lived line asymmetries display oscillation cycles (Stefl
frequencies), which are compared to photometric and stable
spectroscopic frequencies. All Be stars observed with sufficiently
high cadence during an outburst are found to exhibit rapid
oscillations of line asymmetry with a single frequency in the days
following the start of the event. For a given star this circumstellar
frequency may differ only slightly from event to event even when the
outbursts they are associated with have different properties. These
circumstellar frequencies are typically between 0.5 to 2 c/d, and are
generally near photometric frequencies. They are slightly below
prominent (generally stable) spectroscopic frequencies seen in
photospheric absorption lines. The emission asymmetry cycles break
down after roughly 5-10 cycles, with the emission line profile
converging toward approximate symmetry shortly thereafter. In
photometry, several frequencies typically emerge at relatively high
amplitude at some point during the mass ejection process. In all
observed cases, freshly ejected material was initially constrained
within a narrow azimuthal range, indicating it was launched from a
localized region on the stellar surface. The material orbits the star
with a frequency consistent with the near-surface Keplerian orbital
frequency. This material circularizes into a disk configuration after
several orbital timescales. This is true whether or not there was a
preexisting disk at the time of the observed outburst. We find no
evidence for precursor phases prior to the ejection of mass in our
sample. The several photometric frequencies that emerge during
outburst are at least partially stellar in origin.
Description:
Basic information about the targets, measurements of spectroscopic and
photometric quantities during the mass ejection events, fundamental
stellar parameters, and an observing log.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 37 19 List of studied sources
tablea1.dat 102 19 Target list and basic properties
tablea2.dat 120 43 Flicker properties and quantities
tablea3.dat 68 15 *Stellar parameters
tablea4.dat 81 13 Observing log
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Note on tablea3.dat: Parameters from Zorec et al., 2016A&A...595A.132Z 2016A&A...595A.132Z,
Cat. J/A+A/595/A132.
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Common ID
15- 16 I2 h RAh Right ascension (J2000)
18- 19 I2 min RAm Right ascension (J2000)
21- 25 F5.2 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 37 F4.1 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Common ID
13- 18 I6 --- HD HD number
20- 28 I9 --- TIC TESS Input Catalog number
30- 37 A8 --- SpType Spectral type from Simbad
39- 42 F4.2 mag Vmag V-band magnitude
44- 46 I3 km/s vsini ? Projected rotational velocity
48- 54 A7 km/s e_vsini ? Projected rotational velocity error
56 I1 --- r_vsini ? Projected rotational velocity reference (1)
58- 60 I3 km/s vsini2 ? Projected rotational velocity 2
62- 63 I2 km/s e_vsini2 ? Projected rotational velocity 2 error
65 I1 --- r_vsini2 ? Projected rotational velocity 2 reference (1)
67- 74 A8 deg i Inclination angle
76- 84 A9 deg e_i ? Inclination angle error
86 I1 --- r_i ? Inclination angle reference (1)
88- 89 I2 deg i2 ? Inclination angle 2
91- 92 I2 deg e_i2 ? Inclination angle 2 error
94 I1 --- r_i2 ? Inclination angle 2 reference (1)
96- 97 I2 deg i3 ? Inclination angle 3
99-100 I2 deg e_i3 ? Inclination angle 3 error
102 I1 --- r_i3 ? Inclination angle 3 reference (1)
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Note (1): References as follows:
1 = Zorec et al., 2016A&A...595A.132Z 2016A&A...595A.132Z, Cat. J/A+A/595/A132
2 = Sigut et al., 2023ApJ...948...34S 2023ApJ...948...34S
3 = Richardson et al., 2021MNRAS.508.2002R 2021MNRAS.508.2002R
4 = Cochetti et al., 2019A&A...621A.123C 2019A&A...621A.123C
5 = Levenhagen et al., 2011A&A...533A..75L 2011A&A...533A..75L
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Common ID
13- 20 A8 --- FlicType ? Simplicity or complexity of the flicker
22- 26 F5.3 d-1 EmFreq Emission oscillation frequency
28- 33 F6.3 d-1 e_EmFreq ? Emission oscillation frequency error
35- 38 A4 --- r_EmFreq Emission oscillation frequency reference (1)
40- 65 A26 --- Method Method for emission oscillation frequency
67- 69 A3 ct Cycles ? Number of cycles measured
71- 72 A2 --- f_Cycles ? Number of cycles measured flag
74- 78 F5.1 d tb ? duration of photometric build-up time
80- 83 F4.1 d td ? duration of photometric dissipation time
85- 89 F5.1 % Amp ? Amplitude of photometric signal
91-115 A25 d-1 SpPulsFreq ? Spectroscopic pulsation frequencies
117-120 A4 --- r_SpPulsFreq ? Spectroscopic pulsation frequencies
reference (1)
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Note (1): References as follows:
1 = Rivinius et al., 1998A&A...333..125R 1998A&A...333..125R
2 = Rivinius et al., 1998A&A...336..177R 1998A&A...336..177R
3 = Stefl et al., 2003A&A...402..253S 2003A&A...402..253S
4 = Stefl et al., 2003A&A...411..167S 2003A&A...411..167S
5 = Neiner et al., 2002A&A...388..899N 2002A&A...388..899N
6 = Neiner et al., 2005A&A...437..257N 2005A&A...437..257N
7 = Floquet et al., 2000A&A...362.1020F 2000A&A...362.1020F
8 = Stefl et al., 1998ASPC..135..348S 1998ASPC..135..348S
9 = Stefl et al., 1995A&A...294..135S 1995A&A...294..135S
10 = Levenhagen et al., 2003A&A...400..599L 2003A&A...400..599L
11 = Richardson et al., 2021MNRAS.508.2002R 2021MNRAS.508.2002R
12 = Levenhagen et al., 2011A&A...533A..75L 2011A&A...533A..75L
13 = Tubbesing et al., 2000ASPC..214..232T 2000ASPC..214..232T
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Common ID
13- 16 F4.1 Msun Mass Stellar mass
18- 20 F3.1 Msun e_Mass Stellar mass error
22- 25 F4.1 Rsun Req Stellar equatorial radius
27- 29 F3.1 Rsun e_Req Stellar equatorial radius error
31- 34 F4.1 Rsun Rp Stellar polar radius
36- 38 F3.1 Rsun e_Rp Stellar polar radius error
40- 43 F4.2 d-1 forb Orbital frequency at equator
45- 48 F4.2 d-1 e_forb Orbital frequency at equator error
50- 53 F4.2 d-1 fcrit Critical rotation frequency
55- 58 F4.2 d-1 e_fcrit Critical rotation frequency error
60- 63 F4.2 d-1 frot Rotation frequency
65- 68 F4.2 d-1 e_frot Rotation frequency error
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Common ID
12- 34 A23 --- NspecTESS Spectra taken during TESS observations (1)
36- 45 A10 --- TESSSec TESS sectors used (1)
47- 69 A23 --- NspTotal Spectra taken over date range total
71- 81 A11 d DateRange Date range of spec obs (HJD-2457000)
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Note (1): in the NspecTESS and NspecTotal columns the letters indicate:
(N) = NRES spectra
(B) = BeSS spectra
(D) = DAO spectra
(C) = CHIRON spectra
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Acknowledgements:
Jonathan Labadie-Bartz, jbartz(at)udel.edu
(End) Patricia Vannier [CDS] 11-Jun-2025