J/ApJ/928/145 Ha spectroscopic obs. of Pleione from 2005-2019 (Marr+, 2022)
The role of disk tearing and precession in the observed variability of Pleione.
Marr K.C., Jones C.E., Tycner C., Carciofi A.C., Silva A.C.F.
<Astrophys. J., 928, 145 (2022)>
=2022ApJ...928..145M 2022ApJ...928..145M
ADC_Keywords: Stars, Be; Spectra, optical
Keywords: Be stars ; Circumstellar disks ; Massive stars ; Binary stars ;
Spectroscopy ; Photometry ; Polarimetry ; Emission line stars
Abstract:
We acquired Hα spectroscopic observations from 2005 to 2019
showing Pleione has transitioned from a Be phase to a Be-shell phase
during this period. Using the radiative transfer code hdust, we
created a grid of ∼100,000 disk models for Pleione. We successfully
reproduced the observed transition with a disk model that varies in
inclination while maintaining an equatorial density of
ρ0(r)=3x10-11(r/Req)-2.7g/cm3, and an Hα-emitting
region extending to 15Req. We use a precessing disk model to
extrapolate the changing disk inclination over 120 yr and follow the
variability in archival observations. The best-fit disk model
precesses over a line-of-sight inclination between ∼25° and
∼144° with a precessional period of ∼80.5yr. Our precessing models
match some of the observed variability but fail to reproduce all of
the historical data available. Therefore, we propose an ad hoc model
based on our precessing disk model inspired by recent smoothed
particle hydrodynamics simulations of similar systems, where the disk
tears due to the tidal influence of a companion star. In this model, a
single disk is slowly tilted to an angle of 30° from the stellar
equator over 34yr. Then, the disk is torn by the companion's tidal
torque, with the outer region separating from the innermost disk. The
small inner disk returns to the stellar equator as mass injection
remains constant. The outer disk precesses for ∼15yr before gradually
dissipating. The process repeats every 34yr and reproduces all trends
in Pleione's variability.
Description:
Hα spectra of the Be star Pleione were obtained at the Lowell
Observatory, in Flagstaff, AZ, USA, using a fiber-fed echelle
spectrograph connected to the 1.1m John S. Hall telescope. We have
acquired 31 spectra with this instrument from 2005 to 2019 at a
resolving power of 10000 in the Hα region.
Objects:
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RA (ICRS) DE Designation(s)
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03 49 11.21 +24 08 12.1 Pleione = * 28 Tau
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 28 17920 Hα observations of Pleione from the Lowell
Observatory
table2.dat 39 35 Hα emission line profile characteristics of
Pleione
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/440/305 : Fundamental param. of fast-rotating B stars (Fremat+, 2005)
J/ApJS/172/663 : Infrared observations of the Pleiades (Stauffer+, 2007)
J/AJ/143/28 : Analysis of B6-A9 stars from INES UV spectra (Freire+, 2012)
J/A+A/553/A24 : Models for rotating stars (Georgy+, 2013)
J/ApJ/768/128 : K-band calibrated visibilities of 24 Be stars (Touhami+, 2013)
J/ApJ/786/120 : Spectropol. survey of classical Be stars (Draper+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID [1/35] Spectrum identifier number
4- 8 I5 d MJD [53604/58836] Modified Julian date
10- 19 F10.6 nm lambda [648.18/659.9] Wavelength
21- 28 F8.6 --- Flux [0.24/5.4] Flux relative to the continuum
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID [1/35] Spectrum identifier number as
in Table 1; column added by CDS
4- 14 A11 "Y/M/D" Date Date of observation (UT)
16- 20 I5 d MJD [53604/58836] Modified Julian Date
22- 27 F6.3 nm EW [-2.7/-0.6] Equivalent width
29- 33 F5.3 --- Fpk [1.8/5.4] Peak flux, F/Fc, of the Ha profile
35- 39 F5.3 --- V/R [0.8/1.1] Violet (V) to red (R) ratio
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Feb-2024