J/ApJ/798/41 GALEX NUV observations of bright M-type stars (Ansdell+, 2015)
The near-ultraviolet luminosity function of young, early M-type dwarf stars.
Ansdell M., Gaidos E., Mann A.W., Lepine S., James D., Buccino A.,
Baranec C., Law N.M., Riddle R., Mauas P., Petrucci R.
<Astrophys. J., 798, 41 (2015)>
=2015ApJ...798...41A 2015ApJ...798...41A
ADC_Keywords: Stars, M-type ; Photometry, ultraviolet ; X-ray sources ;
Photometry, VRI ; Photometry, infrared ; Spectra, red
Keywords: binaries: close; stars: activity; stars: late-type;
stars: luminosity function, mass function
Abstract:
Planets orbiting within the close-in habitable zones of M dwarf stars
will be exposed to elevated high-energy radiation driven by strong
magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet
(NUV) irradiation can erode and alter the chemistry of planetary
atmospheres, and a quantitative description of the evolution of NUV
emission from M dwarfs is needed when modeling these effects. We
investigated the NUV luminosity evolution of early M-type dwarfs by
cross-correlating the Lepine & Gaidos catalog (2011, J/AJ/142/138) of
bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of
NUV (1771-2831Å) sources. Of the 4805 sources with GALEX
counterparts, 797 have NUV emission significantly (>2.5σ) in
excess of an empirical basal level. We inspected these candidate
active stars using visible-wavelength spectra, high-resolution
adaptive optics imaging, time-series photometry, and literature
searches to identify cases where the elevated NUV emission is due to
unresolved background sources or stellar companions; we estimated the
overall occurrence of these "false positives" (FPs) as ∼16%. We
constructed an NUV luminosity function that accounted for FPs,
detection biases of the source catalogs, and GALEX upper limits. We
found the NUV luminosity function to be inconsistent with predictions
from a constant star-formation rate and simplified age-activity
relation defined by a two-parameter power law.
Description:
We cross-correlated the Lepine+, 2011, J/AJ/142/138, catalog of 8889
nearby (d≲60pc), bright (J<10), K7-M5 stars with the final GALEX data
release.
We obtained medium-resolution (R∼1000) optical spectra for 2128 out of
the 4805 M dwarfs in our sample. The majority of these (1307 spectra)
were acquired using the Super-Nova Integral Field Spectrograph (SNIFS;
red channel: 5100-9700Å) mounted on the University of Hawaii 2.2m
telescope atop Mauna Kea.
The remaining 821 spectra were obtained using four instruments on
three different telescopes: the Mark III spectrograph and the Boller
and Chivens CCD spectrograph on the 1.3m McGraw-Hill telescope at the
MDM Observatory on Kitt Peak (564 spectra); the RC spectrograph on the
1.9m Radcliffe telescope at the South African Astronomical Observatory
(SAAO) in South Africa (67 spectra); and the REOSC spectrograph on the
2.15m Jorge Sahade telescope at the Complejo Astronomico El Leoncito
Observatory (CASLEO) in Argentina (190 spectra).
We observed 193 M dwarfs in our sample in high-resolution with the
Robo-AO laser adaptive optics and imaging system mounted on the
Palomar Observatory 1.5m telescope. These observations were taken from
2013 August 13 to 2014 May 25 (UT).
To identify stars with X-ray counterparts, we cross-correlated our
sample with the ROSAT All-Sky Survey Bright Source Catalog (Voges et
al. 1999, IX/10) and Faint Source Catalog (Voges et al.
2000IAUC.7432....3V 2000IAUC.7432....3V; see also IX/29). See section 2.6.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 93 794 Parameters of UV-luminous early-M dwarfs
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See also:
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/298 : LSPM-North Catalog (Lepine+ 2005)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
J/AJ/148/64 : HAZMAT. I. FUV & NUV emission in early M stars (Shkolnik+, 2014)
J/MNRAS/443/2561 : Trumpeting M dwarfs with CONCH-SHELL (Gaidos+, 2014)
J/MNRAS/437/3133 : Candidate Neptunes around late-type dwarfs (Gaidos+, 2014)
J/A+A/556/A15 : Effective temperature scale of M dwarfs (Rajpurohit+, 2013)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/AJ/145/102 : Bright M dwarfs spectro. in the northern sky (Lepine+, 2013)
J/ApJ/762/88 : Young stellar kinematic group candidate members (Malo+, 2013)
J/ApJ/753/90 : Stellar param. of K5 and later type Kepler stars (Mann+, 2012)
J/AJ/142/138 : All-sky catalog of bright M dwarfs (Lepine+, 2011)
J/A+A/528/A90 : SuperWASP short period eclipsing binaries (Norton+, 2011)
J/MNRAS/411/2770 : Hot white dwarfs in GALEX-DR5 (Bianchi+, 2011)
J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009)
J/AJ/135/2177 : High proper motion stars in the DSS. IV. (Lepine, 2008)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/AJ/133/439 : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
J/AJ/123/3356 : Palomar/MSU nearby star spectrosc. survey. III. (Gizis+, 2002)
http://galex.stsci.edu/GalexView : GALEX viewer
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [PM_]
4- 16 A13 --- PM Stellar identifier (IHHMMm+DDMMWw)
( in Simbad) (1)
18- 22 F5.2 mag Vmag [8.8/14.2] The V band magnitude from Lepine
et al. 2011, J/AJ/142/138
24- 27 F4.2 mag Jmag [5.4/10] The 2MASS J band magnitude
29- 33 F5.2 mag NUV-Ks [5.2/13.6] The (GALEX/NUV-Ks) color index
35- 42 F8.2 uJy FNUV [3.7/15416] GALEX/NUV band flux density
44- 50 F7.2 uJy FFUV [2.7/5710]?=99.99 GALEX/FUV band flux density
52- 59 E8.2 mW/m2 FX ?=9.99 ROSAT X-ray (0.1-2.4keV) flux;
in erg/s/cm2 units
61- 65 F5.2 0.1nm EWHa [-4/55]?=99.99 Hα equivalent width;
in Angstroms units
67- 71 F5.2 [-] logR [-7.5/-4] Fractional NUV luminosity logR'NUV
(R'NUV=(LNUV-Lbasal)/Lbol)
73- 75 A3 --- fp.AO Robo-AO false positive flag (2)
77- 79 A3 --- fp.Ha Low Hα false positive flag (2)
81- 83 A3 --- fp.Sa Shifted Hα false positive flag (2)
85- 87 A3 --- fp.SW SuperWASP false positive flag (2)
89- 93 A5 --- fp [,DLNRY] False positive flag(s) (3)
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Note (1): Identifications from Lepine et al. 2011, J/AJ/142/138:
the first three letters ("PMI") are the SUPERBLINK catalog identifier
(see Lepine et al. 2005, I/298 and 2008, J/AJ/135/2177). These are
followed by five digits which relate to the International Celestial
Reference System (ICRS) right ascension (R.A.) of the star in
sexagesimal; the first four digits are the hours and minutes of R.A.,
the fifth digit is the seconds of R.A. divided by 6 and rounded down
to the nearest integer. These are followed by the declination sign and
then four digits which replicate the ICRS declination (hours, then
minutes) of the source. A disambiguation letter (NSEW) is used when
the scheme would leave two stars with the same name, with the letter
indicating the relative orientation of the stars in the pair.
Note (2): "Yes" indicates a false positive detection (i.e. systems appearing
NUV-luminous for reasons other than stellar youth) by various techniques:
AO = Robo-AO (adaptive optics) detection technique (Section 4.2.1);
no flag if not observed by Robo-AO.
Ha = missing Hα detection technique (Section 4.2.2);
no flag if not part of the missing Hα detection technique.
Sa = Shifted Hα detection technique (Section 4.2.3);
no flag if not part of the shifted Hα detection technique.
SW = SuperWASP detection technique (Section 4.3.4);
no flag if not observed by SuperWASP.
Note (3): False positive (FP) flag as follows:
L = found as FP in literature (Section 4.1);
D = found as FP using detection techniques (Section 4.2, Note (2) above);
N = not found as FP in literature or by FP detection techniques;
R = removed from NUV Luminosity Function derivation (Section 5.2);
Y = YMG (TW Hya Young Moving Group) member used in age-activity
relation derivation (Section 6.2).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 13-May-2015