J/AJ/148/64 HAZMAT. I. FUV and NUV emission in early M stars (Shkolnik+, 2014)
HAZMAT. I. The evolution of Far-UV and Near-UV emission from early M stars.
Shkolnik E.L., Barman T.S.
<Astron. J., 148, 64 (2014)>
=2014AJ....148...64S 2014AJ....148...64S
ADC_Keywords: Stars, early-type ; Stars, M-type ; Spectral types ; Ultraviolet ;
Stars, distances
Keywords: astrobiology - planetary systems - stars: activity -
stars: late-type - surveys - techniques: photometric
Abstract:
The spectral energy distribution, variability, and evolution of the
high-energy radiation from an M dwarf planet host is crucial in
understanding the planet's atmospheric evolution and habitability and
in interpreting the planet's spectrum. The star's extreme-UV (EUV),
far-UV (FUV), and near-UV (NUV) emission can chemically modify,
ionize, and erode the atmosphere over time. This makes determining the
lifetime exposure of such planets to stellar UV radiation critical for
both the evolution of a planet's atmosphere and our potential to
characterize it. Using the early M star members of nearby young moving
groups, which sample critical ages in planet formation and evolution,
we measure the evolution of the GALEX NUV and FUV flux as a function
of age. The median UV flux remains at a "saturated" level for a few
hundred million years, analogous to that observed for X-ray emission.
By the age of the Hyades Cluster (650Myr), we measure a drop in UV
flux by a factor of 2-3 followed by a steep drop from old (several
Gyrs) field stars. This decline in activity beyond 300Myr follows
roughly t-1. Despite this clear evolution, there remains a wide
range, of 1-2 orders of magnitude, in observed emission levels at
every age. These UV data supply the much-needed constraints to M dwarf
upper-atmosphere models, which will provide empirically motivated EUV
predictions and more accurate age-dependent UV spectra as inputs to
planetary photochemical models.
Description:
This work represents the first results of the HAbitable Zones and M
dwarf Activity across Time (HAZMAT) program.
The GALEX satellite was launched on 2003 April 28 and imaged
approximately three-quarters of the sky simultaneously in two
ultraviolet (UV) bands: Far-UV 1350-1750Å and Near-UV
1750-2750Å. One can query the GALEX archive through either CasJobs
(http://mastweb.stsci.edu/gcasjobs/) or the Web tool GalexView
(http://galex.stsci.edu/galexview/). The data presented in this paper
made use of the sixth GALEX data release (GR6/7; for GR5 see cat.
II/312).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 146 215 Target early M stars observed by GALEX
refs.dat 75 27 References
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See also:
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/ApJ/766/9 : GALEX observations of exoplanet host stars (Shkolnik, 2013)
J/ApJ/758/56 : Young M dwarfs within 25pc. II. Kinematics (Shkolnik+, 2012)
J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)
J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009)
J/ApJS/173/673 : M dwarf UV flares in GALEX (Welsh+, 2007)
J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
http://mastweb.stsci.edu/gcasjobs/ : CasJobs
http://galex.stsci.edu/galexview/ : GalexView
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- YMG Name of the Young Moving Group (1)
10- 38 A29 --- Name Name of the star observed by GALEX (2)
40 A1 --- f_Name [d] TWA 31 and TWA 30 B are both known to be
accretors (3)
42- 51 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
53- 62 F10.6 deg DEdeg Declination in decimal degrees (J2000)
64- 68 A5 --- SpT Published spectral type
70- 74 F5.2 mag Jmag [4.2/15.4]? 2MASS J-band magnitude
76 A1 --- n_Dist [-] "-" indicates a photometric distance (4)
77- 80 F4.1 pc Dist [2/80] Hipparcos (cat. I/239) distance (4)
82- 93 A12 --- Bin Binarity type (VB=visual binary, SB=spectroscopic
binary, BD=brown dwarf)
95- 99 F5.1 arcsec Sep [0/114.2]? Binary separation (5)
101 A1 --- l_FFUV [<] Upper limit flag on FFUV
102-107 F6.2 uJy FFUV [0.3/411]? GALEX far-UV (135-175nm) flux density
109-113 F5.2 uJy e_FFUV ? Error in FFUV
115-116 A2 --- f_FFUV [NO] Indicates the star was not observed in FUV
118 A1 --- l_FNUV [<] Upper limit flag on FNUV
119-125 F7.2 uJy FNUV [1/2222]? GALEX near-UV (175-275nm) flux density
127-131 F5.2 uJy e_FNUV ? Error in FNUV
133-134 A2 --- f_FNUV [NO] Indicates the star was not observed in NUV
136-140 A5 --- r_YMG Reference for group membership (in refs.dat file)
142-146 A5 --- r_Bin Reference for binarity (in refs.dat file)
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Note (1): The Young Moving Groups (YMGs) are defined as below:
TWA = TW Hydra Association, 10Myr old;
bPMG = β Pictoris YMG, 12Myr old;
THMG = Tucana-Horologium YMG, 40Myr old;
ADMG = AB Doradus YMG, 100Myr old;
UMA = Ursa Major Association, 300Myr old;
Hyades = Hyades Cluster, 650Myr old;
Field = Old field sample of M stars within 10pc, ∼5Gyr old.
Note (2): Likely mistaken coordinates or object name for the object
"HIP 110526".
Note (3): From Shkolnik et al. (2011ApJ...727....6S 2011ApJ...727....6S) and Looper et al.
(2010ApJ...714...45L 2010ApJ...714...45L), respectively. TWA 30 B's J-band flux is also
extincted, and thus is not included in the analysis.
Note (4): Those with negative signs in front are photometric distances based
on Baraffe et al. 1998 (J/A+A/337/403) models. Hyades members without
individual Hipparcos measurements are assumed to have the cluster distance
of 46.3±0.3pc from Perryman et al. 1998 (J/A+A/331/81).
Note (5): Binaries with separations <35'' are not resolved by GALEX.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref [1/27] Reference number
4- 22 A19 --- BibCode Bibliographic Code
24- 49 A26 --- Aut Author's name
51- 75 A25 --- Cat Catalog in VizieR database
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History:
From electronic version of the journal
References:
Shkolnik et al. Paper I. 2014AJ....148...64S 2014AJ....148...64S This catalog
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 Cat. J/ApJ/872/17
Peacock et al. Paper VI. 2020ApJ...895....5P 2020ApJ...895....5P
(End) Sylvain Guehenneux [CDS] 28-Nov-2014