J/ApJ/834/85 Hα emission in nearby M dwarfs (Newton+, 2017)
The Hα emission of nearby M dwarfs and its relation to stellar rotation.
Newton E.R., Irwin J., Charbonneau D., Berlind P., Calkins M.L., Mink J.
<Astrophys. J., 834, 85-85 (2017)>
=2017ApJ...834...85N 2017ApJ...834...85N (SIMBAD/NED BibCode)
ADC_Keywords: Stars, masses ; Stars, diameters ; Equivalent widths ;
Stars, M-type ; Stars, nearby
Keywords: stars: activity; stars: low-mass; stars: rotation
Abstract:
The high-energy emission from low-mass stars is mediated by the
magnetic dynamo. Although the mechanisms by which fully convective
stars generate large-scale magnetic fields are not well understood, it
is clear that, as for solar-type stars, stellar rotation plays a
pivotal role. We present 270 new optical spectra of low-mass stars in
the Solar Neighborhood. Combining our observations with those from the
literature, our sample comprises 2202 measurements or non-detections
of Hα emission in nearby M dwarfs. This includes 466 with
photometric rotation periods. Stars with masses between 0.1 and
0.6M☉ are well-represented in our sample, with fast and slow
rotators of all masses. We observe a threshold in the mass-period
plane that separates active and inactive M dwarfs. The threshold
coincides with the fast-period edge of the slowly rotating population,
at approximately the rotation period at which an era of rapid
rotational evolution appears to cease. The well-defined
active/inactive boundary indicates that Hα activity is a useful
diagnostic for stellar rotation period, e.g., for target selection for
exoplanet surveys, and we present a mass-period relation for inactive
M dwarfs. We also find a significant, moderate correlation between
LHα/Lbol and variability amplitude: more active stars
display higher levels of photometric variability. Consistent with
previous work, our data show that rapid rotators maintain a saturated
value of LHα/Lbol. Our data also show a clear power-law
decay in LHα/Lbol with Rossby number for slow rotators, with
an index of -1.7±0.1.
Description:
Our sample of M dwarfs is drawn from the MEarth Project, an all-sky
survey looking for transiting planets around approximately 3000
nearby, mid-to-late M dwarfs.
Nutzman & Charbonneau (2008PASP..120..317N 2008PASP..120..317N) selected the northern
MEarth targets from the Lepine & Shara (2005, I/298) northern proper
motion catalog (hereafter the "nearby northern M dwarf" sample).
MEarth-North is located at the Fred Lawrence Whipple Observatory
(FLWO), on Mount Hopkins, Arizona, and has been operational since 2008
September. The observatory comprises eight 40cm telescopes. This work
utilizes results from MEarth-North and from our further spectroscopic
characterization of the sample. Compiled and new rotation period and
Hα measurements are included in Table 1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 185 2202 Magnetic activity measurements and rotation
periods for nearby northern M dwarfs
--------------------------------------------------------------------------------
See also:
I/298 : LSPM-North Catalog (Lepine+ 2005)
J/ApJ/821/93 : Rotation + Galactic kinematics of mid M dwarfs (Newton+, 2016)
J/ApJ/818/153 : MEarth photometry: nearby M-dwarf magnitudes (Dittmann+, 2016)
J/ApJ/812/3 : MEarth mid-to-late M dwarfs rotation + kinematics (West+, 2015)
J/A+A/577/A128 : CARMENES input catalog of M dwarfs. I (Alonso-Floriano+, 2015)
J/ApJ/795/161 : Activity & rotation in Praesepe and the Hyades (Douglas+, 2014)
J/MNRAS/443/2561 : CONCH-SHELL catalog of nearby M dwarfs (Gaidos+, 2014)
J/AJ/148/30 : BVI photometry of 350 Pleiades stars (Kamai+, 2014)
J/ApJS/211/24 : Rotation periods of Kepler MS stars (McQuillan+, 2014)
J/ApJ/784/156 : Parallaxes for nearby mid-to-late M dwarfs (Dittmann+, 2014)
J/AJ/147/20 : Spectroscopy of 447 nearby M dwarfs (Newton+, 2014)
J/MNRAS/432/1203 : Rotation periods of M-dwarf stars (McQuillan+, 2013)
J/MNRAS/431/2063 : UV/X-ray activity of M dwarfs within 10pc (Stelzer+, 2013)
J/AJ/145/102 : Spectro. of bright M dwarfs in the northern sky (Lepine+, 2013)
J/AcA/63/53 : ASAS photometry of ROSAT sources. II. (Kiraga+, 2013)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/MNRAS/423/2966 : Low-mass stars spectroscopy in NGC 2516 (Jackson+, 2012)
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
J/AJ/143/93 : Rotational velocities in early-M stars (Reiners+, 2012)
J/ApJ/746/23 : Radio observations of ultracool dwarf stars (McLean+, 2012)
J/ApJ/743/48 : Stellar rotation periods and X-ray luminosities (Wright+, 2011)
J/A+A/532/A10 : RACE-OC project. II. (Messina+, 2011)
J/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)
J/MNRAS/407/2269 : Polarisation of a sample of late M dwarfs (Morin+, 2010)
J/ApJ/699/649 : Young M dwarfs within 25pc. I. (Shkolnik+, 2009)
J/MNRAS/390/545 : Magnetic field and velocity of early M dwarfs (Donati+, 2008)
J/AJ/133/2825 : Star beyond the NLTT catalog (Reid+, 2007)
J/A+A/467/785 : SuperWASP/ROSAT periodic variable stars (Norton+, 2007)
J/ApJ/648/629 : Radio observations of late M, L, and T dwarfs (Berger+, 2006)
J/AJ/132/866 : New M dwarfs in solar neighborhood (Riaz+, 2006)
J/A+A/446/515 : Distances of nearby ultracool dwarfs (Phan-Bao+, 2006)
J/AJ/130/1871 : Spectroscopic survey of M dwarfs (Bochanski+, 2005)
J/AJ/130/1680 : LSPM-North proper-motion catalog nearby stars (Lepine+, 2005)
J/AJ/128/426 : Subdwarfs in the SDSS (West+, 2004)
J/AJ/125/1598 : New high PM stars in the northern sky (Lepine+, 2003)
J/A+A/397/147 : Activity-rotation relationship in stars (Pizzolato+ 2003)
J/AJ/123/3356 : Palomar/MSU nearby star spectrosc. survey. III. (Gizis+, 2002)
J/AJ/123/2828 : Spectroscopy of northern NLTT stars (Cruz+, 2002)
J/MNRAS/301/1031 : High resolution spectra of VLM stars (Tinney+ 1998)
J/A+A/331/581 : Rotation and activity in field M dwarfs (Delfosse+ 1998)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000)
18- 19 I2 h RAh Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 29 F6.3 s RAs Second of Right Ascension (J2000)
31- 31 A1 --- DE- Sign of the Declination (J2000)
32- 33 I2 deg DEd Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 43 F6.3 arcsec DEs Arcsecond of Declination (J2000)
45- 49 F5.3 Msun Mass [0.05/0.9] Stellar mass
51- 55 F5.3 Rsun Rad [0.07/0.9] Stellar radius
57- 61 F5.3 10-5 chi [0.1/8.4]? χ parameter times 10-5 (1)
63- 70 F8.4 d Per [0.1/151]? Photometric rotation period
72- 90 A19 --- r_Per ADS bibcode for Per
92- 98 F7.3 0.1nm EWHa [-28/0.5]? Hα equivalent width, this work
100-104 F5.3 0.1nm e_EWHa [0.01/0.7]? Error in EWHa
106-112 F7.3 0.1nm EWHa-r [-28/1.3]? Hα EW adopted in
restricted sample
114-118 F5.3 0.1nm e_EWHa-r [0/5.121]? Error in EWHa-r
120-138 A19 --- r_EWHa-r ADS bibcode for EWHa-r
140-145 F6.3 [10-4] logLHa [-0.6/5]? log LHα/Lbol x10-4 relative
to "quiescent" level
147-147 I1 --- l_EWHa-u [0/1] Upper limit flag for EWHa-u;
1=upper limit
149-155 F7.3 0.1nm EWHa-u [-49.6/1.3]? Hα EW adopted in
unrestricted sample
157-161 F5.3 0.1nm e_EWHa-u [0/5.121]? Error in EWHa-u
163-181 A19 --- r_EWHa-u ADS bibcode for EWHa-u
183-183 I1 --- Act Activity flag (0=active, 1=inactive)
185-185 I1 --- Bin Binary flag (0=no known close companion,
1=companion)
--------------------------------------------------------------------------------
Note (1): Calculation of intrinsic Hα luminosity requires absolutely
flux-calibrated spectra. Accurate photometry in the wavelength region
covered by our FAST spectra is not widely available for our sample,
and absolute flux calibration is beyond the scope of the present work.
The χ factor is commonly used in this circumstance
(Walkowicz+ 2004PASP..116.1105W 2004PASP..116.1105W; West & Hawley 2008PASP..120.1161W 2008PASP..120.1161W).
The χ factor is derived from photometric colors, and
LHα/Lbol is then easily calculated:
LHα/Lbol=EWHαxχ. We adopt χ factors from
Douglas et al. (2014, J/ApJ/795/161). See section 3.3.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Jun-2017