J/AJ/154/67 HAZMAT. II. Low-mass stars with GALEX UV observations (Miles+, 2017)
HAZMAT. II. Ultraviolet variability of low-mass stars in the GALEX archive.
Miles B.E., Shkolnik E.L.
<Astron. J., 154, 67-67 (2017)>
=2017AJ....154...67M 2017AJ....154...67M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Photometry, ultraviolet ;
Stars, distances ; Spectral types ; Stars, ages
Keywords: stars: activity - stars: late-type - techniques: photometric -
ultraviolet: planetary systems
Abstract:
The ultraviolet (UV) light from a host star influences a planet's
atmospheric photochemistry and will affect interpretations of
exoplanetary spectra from future missions like the James Webb Space
Telescope. These effects will be particularly critical in the study of
planetary atmospheres around M dwarfs, including Earth-sized planets
in the habitable zone. Given the higher activity levels of M dwarfs
compared to Sun-like stars, time-resolved UV data are needed for more
accurate input conditions for exoplanet atmospheric modeling. The
Galaxy Evolution Explorer (GALEX) provides multi-epoch photometric
observations in two UV bands: near-ultraviolet (NUV; 1771-2831Å)
and far-ultraviolet (FUV; 1344-1786Å). Within 30pc of Earth, there
are 357 and 303 M dwarfs in the NUV and FUV bands, respectively, with
multiple GALEX observations. Simultaneous NUV and FUV detections exist
for 145 stars in both GALEX bands. Our analyses of these data show
that low-mass stars are typically more variable in the FUV than the
NUV. Median variability increases with later spectral types in the NUV
with no clear trend in the FUV. We find evidence that flares increase
the FUV flux density far more than the NUV flux density, leading to
variable FUV to NUV flux density ratios in the GALEX bandpasses.The
ratio of FUV to NUV flux is important for interpreting the presence of
atmospheric molecules in planetary atmospheres such as oxygen and
methane as a high FUV to NUV ratio may cause false-positive
biosignature detections. This ratio of flux density in the GALEX bands
spans three orders of magnitude in our sample, from 0.008 to 4.6, and
is 1 to 2 orders of magnitude higher than for G dwarfs like the Sun.
These results characterize the UV behavior for the largest set of
low-mass stars to date.
Description:
In this second paper of the HAbitable Zones and M dwarf Activity
across Time (HAZMAT) series, we use archived data from both Galaxy
Evolution Explorer (GALEX) photometric bands to measure the
variability of 376 low-mass stars with spectral types ranging from K7
to M7.
Our target list consisted of 1124 low-mass stars with photometric
distances out to 25pc of Earth assuming field ages (Reid et al. 2007,
Cat. J/AJ/133/2825).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 145 376 Low-mass stars with multiple Galaxy Evolution
Explorer (GALEX) ultraviolet (UV) observations
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
J/A+A/577/A128 : CARMENES input catalogue. I (Alonso-Floriano+, 2015)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/AJ/148/64 : HAZMAT. I. UV emission in early M stars (Shkolnik+, 2014)
J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)
J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)
J/AJ/145/102 : Spectroscopy of bright M dwarfs (Lepine+, 2013)
J/AJ/143/80 : Low-mass members of B Pic & AB DOR (Schlieder+, 2012)
J/A+A/556/A15 : Effective temperature scale of M dwarfs (Rajpurohit+, 2013)
J/ApJ/758/56 : Young M dwarfs within 25pc. II. Kinematics (Shkolnik+, 2012)
J/ApJ/704/975 : Rotational velocities for M dwarfs (Jenkins+, 2009)
J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009)
J/AJ/133/2825 : Star beyond the NLTT catalog (Reid+, 2007)
J/AJ/132/161 : NStars project: The southern sample. I. (Gray+, 2006)
J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)
J/A+A/442/211 : Spectroscopic distances of 322 NLTT stars (Scholz+, 2005)
J/AJ/126/2048 : NStars project: the Northern Sample. I. (Gray+, 2003)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 16 A16 --- Name Star name
17 A1 --- f_Name [h] Flag on Name (h=IRXS source; there is only
one)
19- 27 F9.5 deg RAdeg Right Ascension in decimal degrees
(Eq=J2000, Epoch=2007)
29- 37 F9.5 deg DEdeg Declination in decimal degrees
(Eq=J2000, Epoch=2007)
39- 42 A4 --- SpT Spectral type
44- 47 I4 Myr Age [15/5000] Age (1)
49- 50 I2 --- r_Age [7/18]? Age reference (2)
52- 53 I2 --- r_SpT [1/16]? Spectral type reference (2)
55- 58 F4.1 pc Dist [1.7/29.4] Distance
60- 61 I2 --- Ndet [1/81]? Number of Near-UltraViolet (NUV;
1771-2831Å) detections
63 I1 --- Nul [1/2]? Number of NUV upper limits
65- 66 A2 --- l_ [≤] Upper limit flag on
67- 73 F7.2 uJy [1.07/3844.76]? Mean NUV flux density
(fNUV, µ) (3)
75- 79 F5.2 uJy e_ [0.04/85.17]? Error in
81- 82 A2 --- l_SNUV0 [≤] Upper limit flag on SNUV0
83- 89 F7.2 uJy SNUV0 [0.64/3804.04]? Minimum NUV flux density (3)
91- 97 F7.2 uJy SNUV1 [1.48/3920.06]? Maximum NUV flux density (3)
99-102 F4.2 --- NMAD [0/0.76]? NUV Median Absolute Deviation (MAD)
divided by the median indicated by MADrel in
our plots
104-105 I2 --- Fdet [1/15]? Number of Far-UltraViolet (FUV;
1344-1786Å) detections
107-108 I2 --- Ful [1/79]? Number of FUV upper limits
110-111 A2 --- l_ [≤] Upper limit flag on
112-118 F7.2 uJy [0.38/1663.33]? Mean FUV flux density
(fFUV, µ) (3)
120-124 F5.2 uJy e_ [0.03/41.17]? Error in
126-127 A2 --- l_SFUV0 [≤] Upper limit flag on SFUV0
128-133 F6.2 uJy SFUV0 [0.14/309.92]? Minimum FUV flux density (3)
135-140 F6.2 uJy SFUV1 [0.46/603.74]? Maximum FUV flux density (3)
142-145 F4.2 --- FMAD [0/0.86]? FUV Median Absolute Deviation (MAD)
divided by the median indicated by MADrel in
our plots
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Note (1): If no age is provided by the literature, the star is assumed to be
5Gyr old.
Note (2): The reference codes are defined as follows:
1 = Reid et al. 2007 (Cat. J/AJ/133/2825);
2 = Reid et al. 1995 (Cat. III/198), Hawley et al. 1996 (Cat. III/198);
3 = Alonso-Floriano et al. 2015 (Cat. J/A+A/577/A128);
4 = Gray et al. 2003 (Cat. J/AJ/126/2048);
5 = Gray et al. 2006 (Cat. J/AJ/132/161);
6 = Jenkins et al. 2009 (Cat. J/ApJ/704/975);
7 = Kraus et al. 2014 (Cat. J/AJ/147/146);
8 = Lepine et al. 2013 (Cat. J/AJ/145/102);
9 = Mann et al. 2015 (Cat. J/ApJ/804/64);
10 = Newton et al. 2014 (Cat. J/AJ/147/20);
11 = Rajpurohit et al. 2013 (Cat. J/A+A/556/A15);
12 = Scholz et al. 2005 (Cat. J/A+A/442/211);
13 = Shkolnik et al. 2009 (Cat. J/ApJ/699/649);
14 = Shkolnik et al. 2012 (Cat. J/ApJ/758/56);
15 = Shkolnik et al. (2014ApJ...796L..20S 2014ApJ...796L..20S);
16 = Torres et al. 2006 (Cat. J/A+A/460/695);
17 = Schlieder et al. 2012 (Cat. J/AJ/143/80);
18 = Shkolnik et al. 2017 (Cat. J/AJ/154/69).
Note (3): Values are scaled to 10pc.
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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 This catalog
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] 08-Nov-2017