J/ApJ/921/122 Chromospheric activity of ρ CrB and 88 Leo (Metcalfe+, 2021)
Magnetic and rotational evolution of ρ CrB from asteroseismology with TESS.
Metcalfe T.S., van Saders J.L., Basu S., Buzasi D., Drake J.J.,
Egeland R., Huber D., Saar S.H., Stassun K.G., Ball W.H., Campante T.L.,
Finley A.J., Kochukhov O., Mathur S., Reinhold T., See V., Baliunas S.,
Soon W.
<Astrophys. J., 921, 122 (2021)>
=2021ApJ...921..122M 2021ApJ...921..122M
ADC_Keywords: Asteroseismology; Stars, G-type; Stars, diameters; Stars, masses;
Stars, ages; Optical; X-ray sources
Keywords: Stellar activity ; Stellar evolution ; Stellar oscillations ;
Stellar rotation ; Stellar winds
Abstract:
During the first half of main-sequence lifetimes, the evolution of
rotation and magnetic activity in solar-type stars appears to be
strongly coupled. Recent observations suggest that rotation rates
evolve much more slowly beyond middle age, while stellar activity
continues to decline. We aim to characterize this midlife transition
by combining archival stellar activity data from the Mount Wilson
Observatory with asteroseismology from the Transiting Exoplanet Survey
Satellite (TESS). For two stars on opposite sides of the transition
(88 Leo and ρ CrB), we independently assess the mean activity
levels and rotation periods previously reported in the literature. For
the less active star (ρ CrB), we detect solar-like oscillations
from TESS photometry, and we obtain precise stellar properties from
asteroseismic modeling. We derive updated X-ray luminosities for both
stars to estimate their mass-loss rates, and we use previously
published constraints on magnetic morphology to model the evolutionary
change in magnetic braking torque. We then attempt to match the
observations with rotational evolution models, assuming either
standard spin-down or weakened magnetic braking. We conclude that the
asteroseismic age of ρ CrB is consistent with the expected
evolution of its mean activity level and that weakened braking models
can more readily explain its relatively fast rotation rate. Future
spectropolarimetric observations across a range of spectral types
promise to further characterize the shift in magnetic morphology that
apparently drives this midlife transition in solar-type stars.
Description:
Both ρ CrB and 88 Leo have synoptic S-index time series from the
Mount Wilson Observatory (MWO) HK Project, ranging from near the
beginning of the program in 1966 to its termination in 2003 (see
Figure 1). The MWO S-index measures the ratio of emission from 1Å
cores of the CaII H and K lines to the sum of two nearby 20Å
pseudo-continuum bandpasses. See Section 2.1.
The Transiting Exoplanet Survey Satellite (TESS) observed ρ CrB in
2-minute cadence for a total of approximately 52 days during Sectors
24 and 25 of Cycle 2 (2020 April 15-2020 June 08).
TESS observed 88 Leo in 2-minute cadence for a total of approximately
27 days during Sector 22 of Cycle 2 (2020 February 18-2020 March 18).
See Section 2.2.
We obtained a Chandra observation of ρ CrB using the High
Resolution Camera imaging detector (HRC-I) on 2020 April 19 starting
at UT 14:59 for a net exposure time of 11870s (ObsID #22308). An
earlier observation of ρ CrB had also been obtained (PI: S. Saar)
several years earlier on 2012 January 17 beginning at UT 13:12 using
the Advanced CCD Imaging Spectrometer spectroscopic array (ACIS-S) on
the back-illuminated CCD ("s3") for a net exposure of 9835s
(obsID #12396).
See Section 2.4.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
16 01 02.66 +33 18 12.6 rho CrB = HD 143761
11 31 44.94 +14 21 52.2 88 Leo = HD 100180
----------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 146 3 Stellar properties of ρ CrB and 88 Leo
fig1.dat 26 6053 Time series for ρ CrB (HD 143761) and
88 Leo (HD 100180)
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/335 : Revised cat. of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
J/A+A/619/A73 : Age-chromospheric activity (Lorenzo-Oliveira+, 2018)
J/ApJ/457/L99 : 25yr CaII-HK obs. of F-K nearby stars (Baliunas+, 1996)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)
J/ApJ/743/48 : Stars with rot. periods and X-ray luminosities (Wright+, 2011)
J/ApJS/199/8 : Interstellar column densities compilation (Gudennavar+, 2012)
J/A+A/580/A23 : Stroemgren-Crawford uvbyβ photometry cat. (Paunzen, 2015)
J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)
J/ApJ/830/46 : RVs of 3 Neptune-mass planet hosts (Fulton+, 2016)
J/AJ/152/180 : Bol. fluxes of eclipsing binaries in Tycho-2 (Stassun+, 2016)
J/AJ/153/136 : Planets & their host stars with Gaia plx (Stassun+, 2017)
J/ApJ/854/78 : Magnetohydrodynamic (MHD) simulations. II. (Finley+, 2018)
J/ApJ/858/28 : Mixing-length param. for a sample of KIC stars (Viani+, 2018)
J/ApJS/241/12 : Asteroseismic Target List (ATL) for TESS (Schofield+, 2019)
J/ApJ/888/43 : APOGEE-Kepler Cool Dwarf star ages (Claytor+, 2020)
J/ApJ/900/154 : Mount Wilson S-Index of 94 Aqr A & 94 Aqr B (Metcalfe+, 2020)
J/other/NatAs/5.707 : Dwarf stars asteroseismic rotation rates (Hall+, 2021)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD identifier
8 A1 --- n_HD Note on HD 143761 (rho CRB) (1)
10- 15 F6.3 --- logRHK [-5.177/-4.958]? Chromospheric activity,
logR'HK[Teff] (see Section 4)
17- 21 F5.3 --- e_logRHK [0.015]? logRHK uncertainty
23 I1 --- r_logRHK [1] Reference on logRHK (2)
25- 28 F4.1 d Prot [15/20.3]? Rotational period
30- 32 F3.1 d e_Prot [0.3/2]? Prot uncertainty
34 I1 --- r_Prot [1] Reference on Prot (2)
36- 39 I4 K Teff [5817/6002] Effective temperature
41- 42 I2 K e_Teff [33/78] Lower uncertainty on Teff
44- 45 I2 K E_Teff [32/78] Upper uncertainty on Teff
47 I1 --- r_Teff [2] Reference on Teff (2)
49- 53 F5.2 [Sun] [M/H] [-0.2/0.04] Metallicity
55- 58 F4.2 [Sun] e_[M/H] [0.06/0.07] [M/H] uncertainty
60 I1 --- r_[M/H] [2] Reference on [M/H] (2)
62- 66 F5.3 [cm/s2] logg [4.19/4.38] Log of surface gravity
68- 72 F5.3 [cm/s2] e_logg [0.008/0.08] logg uncertainty
74 I1 --- r_logg [2] Reference on logg (2)
76- 80 F5.3 Rsun Rad [1.127/1.31] Radius
82- 86 F5.3 Rsun e_Rad [0.01/0.04] Rad uncertainty
88 I1 --- r_Rad [3] Reference on Rad (2)
90- 94 F5.3 Lsun Lum [1.48/1.75] Luminosity
96-100 F5.3 Lsun e_Lum [0.04/0.1] Lower uncertainty on Lum
102-106 F5.3 Lsun E_Lum [0.036/0.1] Upper uncertainty on Lum
108 I1 --- r_Lum [3] Reference on Lum (2)
110-113 F4.2 Msun Mass [0.96/1.14] Mass
115-118 F4.2 Msun e_Mass [0.02/0.07] Mass uncertainty
120 I1 --- r_Mass [3] Reference on Mass (2)
122-124 F3.1 Gyr Age [2.4/9.8] Age
126-128 F3.1 Gyr e_Age [0.4/0.6] Lower uncertainty on Age
130-132 F3.1 Gyr E_Age [0.4/0.7] Upper uncertainty on Age
134 I1 --- r_Age [4] Reference on Age (2)
136-139 F4.2 [10+20W] Lx [0.9/6.1]? X-ray luminosity in 1027erg/s
141-144 F4.2 [10+20W] e_Lx [0.19/2.1]? Lx uncertainty
146 I1 --- r_Lx [5] Reference on Lx (2)
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Note (1): Note as follows:
a = asteroseismic
o = other
Note (2): Reference code as follows:
1 = Section 2.1;
2 = Brewer et al. (2016, J/ApJS/225/32);
3 = Section 2.3;
4 = Barnes (2007ApJ...669.1167B 2007ApJ...669.1167B);
5 = Section 2.4.
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Byte-by-byte Description of file: fig1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD HD identifier
9- 19 F11.5 d JD [-804.2/12439.8] Julian Date; JD-2440000
21- 26 F6.4 --- SInd [0.127/0.4] S-Index value
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 23-Feb-2023