J/ApJ/872/17 HAZMAT. V. UV and X-ray evolution of K stars (Richey-Yowell+, 2019)
HAZMAT.
V. The ultraviolet and X-ray evolution of K stars.
Richey-Yowell T., Shkolnik E.L., Schneider A.C., Osby E., Barman T.,
Meadows V.S.
<Astrophys. J., 872, 17 (2019)>
=2019ApJ...872...17R 2019ApJ...872...17R
ADC_Keywords: Stars, K-type; Photometry, ultraviolet; X-ray sources;
Stars, masses; Stars, ages; Stars, distances
Keywords: stars: evolution ; stars: low-mass
Abstract:
Knowing the high-energy radiation environment of a star over a
planet's formation and evolutionary period is critical in determining
if that planet is potentially habitable and if any biosignatures could
be detected, as UV radiation can severely change or destroy a planet's
atmosphere. Current efforts for finding a potentially habitable planet
are focused on M stars, yet K stars may offer more habitable
conditions due to decreased stellar activity and more distant and
wider habitable zones (HZs). While M star activity evolution has been
observed photometrically and spectroscopically, there has been no
dedicated investigation of K star UV evolution. We present the first
comprehensive study of the near-UV, far-UV, and X-ray evolution of K
stars. We used members of young moving groups and clusters ranging in
age from 10 to 625Myr combined with field stars and their archived
GALEX UV and ROSAT X-ray data to determine how the UV and X-ray
radiation evolve. We find that the UV and X-ray flux incident on an HZ
planet is 5-50 times lower than that of HZ planets around early-M
stars and 50-1000 times lower than those around late-M stars, due to
both an intrinsic decrease in K dwarf stellar activity occurring
earlier than for M dwarfs and the more distant location of the K dwarf HZ.
Description:
We compiled K stars in young moving groups (YMGs) and clusters ranging
in age from 10 to 625Myr.
We cross referenced proper-motion-corrected coordinates of our sample
to GALEX.
To compare X-ray and UV data, we cross referenced our sample of K
stars with the Second ROSAT All-sky Survey Point Source Catalog (2RXS;
Boller+, 2016, J/A+A/588/A103).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 55 10 Number of K stars in each group or cluster
table3.dat 180 455 Observed flux densities, fluxes, and model
photospheric flux densities of the stars
used in this analysis
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
J/MNRAS/328/45 : Late-type stars members of young groups (Montes+, 2001)
J/AJ/134/2340 : Praesepe & Coma Berenices cluster memberships (Kraus+, 2007)
J/ApJ/761/166 : Terrestrial exoplanet atmospheres. I. (Hu+, 2012)
J/MNRAS/422/2024 : X-ray-age relation & exoplanet evaporation (Jackson+, 2012)
J/A+A/559/A43 : Pan-STARRS1 (PS1) obs. of the Hyades (Goldman+, 2013)
J/ApJ/762/88 : Young stellar kinematic group cand. members (Malo+, 2013)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)
J/AJ/148/64 : HAZMAT. I. FUV & NUV in early M stars (Shkolnik+, 2014)
J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015)
J/A+A/588/A103 : 2nd ROSAT all-sky survey (2RXS) source cat. (Boller+, 2016)
J/AJ/154/67 : HAZMAT. II. Low-mass stars with GALEX UV obs. (Miles+, 2017)
J/AJ/154/69 : ACRONYM II. β Pictoris Moving Group (Shkolnik+, 2017)
J/ApJS/239/2 : Simulated exoplanets from TESS targets (Barclay+, 2018)
J/AJ/155/122 : HAZMAT. III. Low-mass stars GALEX photom. (Schneider+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Cluster Group/Cluster designation as in Table 3
19 A1 --- u_Age [~] Uncertainty flag on Age
20- 23 I4 Myr Age Age
25- 26 I2 Myr e_Age [3/50]? Negative error on Age
28- 29 I2 Myr E_Age [3/51]? Positive error on Age
31 A1 --- r_Age Age reference (1)
33- 35 I3 --- Nin [3/310] Number of K stars in input sample
37- 39 I3 --- Nnuv [1/229] Number of K stars observed in NUV
by GALEX
41- 43 I3 --- DetNUV [1/169] Number of K stars detected in NUV
by GALEX
45- 47 I3 --- Nfuv [1/211] Number of K stars observed in FUV
by GALEX
49- 51 I3 --- DetFUV [1/152] Number of K stars detected in FUV
by GALEX
53- 55 I3 --- Nx [0/107] Number of K stars detected in X-ray
by ROSAT
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Note (1): References as follows:
a = Bell et al. (2015, J/MNRAS/454/593),
b = Shkolnik et al. (2017, J/AJ/154/69),
c = Jones et al. (2015ApJ...813...58J 2015ApJ...813...58J & 2017AAS...22913105J 2017AAS...22913105J),
d = Kraus & Hillenbrand (2007, J/AJ/134/2340),
e = Perryman et al. (1997, J/A+A/331/81).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Cluster Group/Cluster
19- 22 I4 Myr Age [10/5000] Age (1)
24- 44 A21 --- Name Simbad Name (2)
46- 47 I2 h RAh Hour of Right Ascension (J2000)
49- 50 I2 min RAm Minute of Right Ascension (J2000)
52- 59 F8.5 s RAs Second of Right Ascension (J2000)
61- 61 A1 --- DE- Sign of the Declination (J2000)
62- 63 I2 deg DEd Degree of Declination (J2000)
65- 66 I2 arcmin DEm Arcminute of Declination (J2000)
68- 74 F7.4 arcsec DEs Arcsecond of Declination (J2000)
76- 79 F4.2 Msun Mass [0.5/1] Derived stellar mass
81- 86 F6.2 pc Dist [3.2/355.4] Distance
88- 95 E8.2 uJy SJ [1870000/568000000] Observed J band flux
density
97-104 E8.2 uJy sigJ [4760000/32400000] J band model photospheric
flux density (σJ)
106-106 A1 --- l_SNUV Limit flag on S-NUV
108-115 E8.2 uJy SNUV [5/3460000]? Observed GALEX NUV
(1771-2831Å) flux density
117-124 E8.2 uJy e_SNUV [1/13200]? Uncertainty in S-NUV
126-133 E8.2 uJy sigNUV [18.7/31100]? NUV model photospheric
flux density (σNUV)
135-135 A1 --- l_SFUV Limit flag on S-FUV
137-144 E8.2 uJy SFUV [2.5/165000]? Observed GALEX FUV
(1344-1786Å) flux density
146-153 E8.2 uJy e_SFUV [0.5/1850]? Uncertainty in S-FUV
155-162 E8.2 uJy sigFUV [3.2e-5/3.1]? FUV model photospheric
flux density (σFUV)
164-171 E8.2 mW/m2 Fx [1e-13/2.4e-10]? Observed X-ray flux
173-180 E8.2 mW/m2 e_Fx [1.4e-14/2.6e-11]? Uncertainty in Fx
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Note (1): Using the effective stellar temperatures in Pecaut & Mamajek
(2013, J/ApJS/208/9) and the model isochrones from
Baraffe+ (2015A&A...577A..42B 2015A&A...577A..42B), we determine mass estimates for the
spectral types used in this work following Table 1. We used masses
from 0.6 to 0.9M☉ but allowed one spectral subtype lower and higher
to account for spectral type uncertainty. Table 1:
------------------------------------------------------------
SpT TW Hya beta Pic Tuc-Hor AB Dor UMa Hyades Field
------------------------------------------------------------
10Myr 24Myr 45Myr 149Myr 300Myr 625Myr 5Gyr
------------------------------------------------------------
K0 1.30 0.98 0.90 0.93 0.92 0.92 0.89
K1 1.26 0.96 0.88 0.89 0.89 0.89 0.86
K2 1.20 0.93 0.86 0.86 0.86 0.86 0.83
K3 1.10 0.89 0.83 0.80 0.80 0.80 0.79
K4 0.98 0.83 0.80 0.75 0.75 0.75 0.74
K5 0.90 0.78 0.77 0.71 0.71 0.71 0.70
K6 0.78 0.74 0.72 0.63 0.65 0.66 0.65
K7 0.75 0.72 0.69 0.59 0.62 0.62 0.61
K8 0.72 0.71 0.66 0.57 0.60 0.60 0.60
K9 0.68 0.68 0.63 0.54 0.57 0.57 0.57
M0 0.59 0.62 0.60 0.51 0.56 0.53 0.53
M1 0.49 0.52 0.52 0.45 0.50 0.47 0.47
------------------------------------------------------------
Note (2): Names beginning with "J" are 2MASS identifiers; otherwise SIMBAD
names are used.
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History:
From electronic version of the journal
References:
Shkolnik et al. Paper I. 2014AJ....148...64S 2014AJ....148...64S Cat. J/AJ/148/64
Miles et al. Paper II. 2017AJ....154...67M 2017AJ....154...67M Cat. J/AJ/154/67
Schneider et al. Paper III. 2018AJ....155..122S 2018AJ....155..122S Cat. J/AJ/155/122
Parke Loyd et al. Paper IV. 2018ApJ...867...70P 2018ApJ...867...70P
Richey-Yowell et al. Paper V. 2019ApJ...872...17R 2019ApJ...872...17R This catalog
Peacock et al. Paper VI. 2020ApJ...895....5P 2020ApJ...895....5P
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-Jul-2020