J/ApJ/902/24 Evolved massive stars with TESS. II. (Dorn-Wallenstein+, 2020)
Short-term variability of evolved massive stars with TESS.
II. A new class of cool, pulsating supergiants.
Dorn-Wallenstein T.Z., Levesque E.M., Neugent K.F.,
Davenport J.R.A., Morris B.M., Gootkin K.
<Astrophys. J., 902, 24 (2020)>
=2020ApJ...902...24D 2020ApJ...902...24D
ADC_Keywords: Stars, supergiant; Photometry; Proper motions; Optical
Keywords: Massive stars ; Evolved stars ; Supergiant stars ;
Light curves ; Stellar pulsations ; Red supergiant stars ;
Multi-periodic pulsation ; Wavelet analysis ;
Lomb-Scargle periodogram ; Asteroseismology ; Stellar astronomy ;
Yellow hypergiant stars
Abstract:
Massive stars briefly pass through the yellow supergiant (YSG) phase
as they evolve redward across the H-R diagram and expand into red
supergiants (RSGs). Higher-mass stars pass through the YSG phase again
as they evolve blueward after experiencing significant RSG mass loss.
These post-RSG objects offer us a tantalizing glimpse into which stars
end their lives as RSGs and why. One telltale sign of a post-RSG
object may be an instability to pulsations, depending on the star's
interior structure. Here we report the discovery of five YSGs with
pulsation periods faster than 1 day, found in a sample of 76 cool
supergiants observed by the Transiting Exoplanet Survey Satellite
(TESS) at a two-minute cadence. These pulsating YSGs are concentrated
in an H-R diagram region not previously associated with pulsations; we
conclude that this is a genuine new class of pulsating star, fast
yellow pulsating supergiants (FYPSs). For each FYPS, we extract
frequencies via iterative prewhitening and conduct a time-frequency
analysis. One FYPS has an extracted frequency that is split into a
triplet, and the amplitude of that peak is modulated on the same
timescale as the frequency spacing of the triplet; neither rotation
nor binary effects are likely culprits. We discuss the evolutionary
status of FYPS and conclude that they are candidate post-RSGs. All
stars in our sample also show the same stochastic low-frequency
variability found in hot OB stars and attributed to internal gravity
waves. Finally, we find four α Cygni variables in our sample, of
which three are newly discovered.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 100 76 Names, proper motions, TESS magnitudes and
positions in the HR diagram of the cool
supergiants observed by TESS
table2.dat 85 76 Fit parameters from Equation (1), and
corresponding errors for all stars in our sample
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Note on table1.dat: In the FTP table, the stars are ordered by effective
temperature from coolest to warmest.
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See also:
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
J/MNRAS/402/2087 : Optical polarization of OJ 287 in 2005-2009
J/A+AS/101/421 : uvby-beta photometry of GP And (Rodriguez+ 1993)
J/AJ/106/591 : OP Survey of Halo early-type stars (Rodgers+ 1993)
J/A+AS/106/141 : Photometry of luminous blue variables (Spoon+ 1994)
J/AJ/121/2148 : Spectral types for 372 A, F & G stars (Gray+, 2001)
J/A+A/374/712 : Photometric observations of comets (Szabo+, 2001)
J/AJ/125/277 : High PMs in central Orion nebula (O'dell+, 2003)
J/ApJ/680/130 : MIR colors of AGNs in the MUSYC ECDF-S (Cardamone+, 2008)
J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009)
J/MNRAS/395/1409 : Type II-P SN progenitor constraints (Smartt+, 2009)
J/A+A/502/937 : Radial velocities of 9 O-type stars (Mahy+, 2009)
J/ApJ/719/1784 : Yellow supergiants in the SMC (Neugent+, 2010)
J/A+A/533/A4 : CoRoT photometry of three O-type stars (Blomme+, 2011)
J/A+A/537/A146 : Stellar models with rotation. 0.8<M<120 (Ekstrom+, 2012)
J/ApJ/749/177 : Yellow and red supergiants in the LMC (Neugent+, 2012)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/A+A/544/A53 : Long-term phot. & spectroscopy of EE Cep (Galan+, 2012)
J/A+A/560/A16 : Comparison of evolutionary tracks (Martins+, 2013)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/A+A/556/A52 : γ Dor stars from Kepler (Tkachenko+, 2013)
J/MNRAS/434/2418 : [Fe/H] of short-period Gal. Cepheids (Klagyivik+, 2013)
J/A+A/567/A68 : Gas accretion in nearby spiral gal. (Di Teodoro+, 2014)
J/AJ/156/102 : TESS Input Cat. & Candidate Target List (Stassun+, 2018)
J/A+A/629/A100 : MUSE library of stellar spectra (Ivanov+, 2019)
J/ApJ/872/L9 : TESS obs. of massive O and B stars (Pedersen+, 2019)
J/A+A/640/A36 : OB stars TESS phot. & high-res. spec. (Bowman+, 2020)
J/ApJ/889/44 : UKIRT obs. of red supergiants in M31 (Neugent+, 2020)
J/ApJ/747/L19 : A search for type Ia SNR B0519-69.0 progenitors
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Common Name
17- 25 I9 --- TIC [13249363/467450857] TESS input catalog ID
27- 38 F12.8 deg RAdeg [17/358.3] TIC right ascension (J2000)
40- 51 F12.8 deg DEdeg [-70.05/64.4] TIC declination (J2000)
53- 58 F6.3 mas/yr pmRA [-7.45/2.32] TIC proper motion in right
ascension
60- 65 F6.3 mas/yr pmDE [-6.28/3.64] TIC proper motion in declination
67- 72 F6.3 mag Tmag [4.1/11.97] TESS magnitude
74- 78 F5.3 [K] logTeff [3.53/4.04] log of surface temperature (1)
80- 84 F5.3 [Lsun] logLstar [4.04/5.47] log of luminosity (1)
86- 86 A1 --- Ref Source of logTeff and logLstar (2)
88- 88 A1 --- HRType Type from HR diagram: "R"=RSG (48 occurrences);
Y=YSG (28 occurrences)
90-100 A11 --- VarType Variable type: α Cygni or new fast yellow
pulsating supergiant ("FYPS")
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Note (1): Typical uncertainties in logTeff and logLstar are 0.015dex and
0.10dex respectively in Neugent+ (2012, J/ApJ/749/177).
M stars from Levesque+ (see "L" in column "Ref") have uncertainties of 25K
and 0.1dex respectively, while the uncertainties in Teff in K stars are
somewhat larger (100K).
Note (2): The source of logTeff and logstar measurements as follows:
N = Neugent et al. (2012, J/ApJ/749/177);
L = Levesque et al. (2005ApJ...628..973L 2005ApJ...628..973L, 2006ApJ...645.1102L 2006ApJ...645.1102L,
2007arXiv0708.2914L 2007arXiv0708.2914L, 2009AJ....137.4744L 2009AJ....137.4744L);
I = Ivanov et al. (2019, J/A+A/629/A100);
T = TESS Input catalog, Stassun+ (2018, J/AJ/156/102).
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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- 15 A15 --- Name Common Name
17- 25 I9 --- TIC [13249363/467450857] TESS input catalog ID
27- 35 F9.4 10-3 alpha0 [7.6/2202] Parameter α0,
from Equation 1 (3)
37- 44 F8.4 10-3 e_alpha0 [0.27/261] Uncertainty in alpha0
46- 51 F6.4 d tau [0.03/2.6] Parameter τ,
from Equation 1 (3)
53- 58 F6.4 d e_tau [0.0014/0.6] Uncertainty in tau
60- 64 F5.3 --- gamma [1.26/3.04] Parameter γ
from Equation 1 (3)
66- 70 F5.3 --- e_gamma [0.005/0.15] Uncertainty in gamma
72- 78 F7.4 10-3 alphaw [1.55/52.67] Parameter αw,
from Equation 1 (3)
80- 85 F6.4 10-3 e_alphaw [0.0006/0.09] Uncertainty in alphaw
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Note (3): Parameters for Equation 1 from Stanishev+ (2002A&A...394..625S 2002A&A...394..625S)
α(f)=(α0/(1+(2πτf)γ))+αw
where:
α0 = the amplitude as frequency => 0 in units of normalized flux;
τ = characteristic timescale in days on which the noise is
correlated;
γ = sets the slope of the red noise;
αw = an additional parameter we add in to model the white noise
floor at the highest frequencies, also in units of
normalized flux.
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History:
From electronic version of the journal
References:
Dorn-Wallenstein et al. Paper I. 2019ApJ...878..155D 2019ApJ...878..155D
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Jan-2022