J/AJ/166/63 Mind the Gap. I. Ha activity for M-Dwarfs (Jao+, 2023)
Mind the Gap.
I. Ha Activity of M-Dwarfs Near the Partially/Fully Convective Boundary and a
New Ha Emission Deficiency Zone on the Main Sequence
Jao W.-C., Henry T.J., White R.J., Nisak A.H., Hubbard-James H.-S.,
Paredes L.A., Lewis V.B.J.
<Astron. J., 166, 63 (2023)>
=2023AJ....166...63J 2023AJ....166...63J
ADC_Keywords: Stars, M-type; Spectra, optical; Proper motions;
Parallaxes, trigonometric; Radial velocities
Keywords: Hertzsprung-Russell diagram ; M dwarf stars ; Stellar activity
; Stellar rotation ; High-resolution spectroscopy
Abstract:
Since identifying the gap in the H-R Diagram (HRD) marking the
transition between partially and fully-convective interiors, a unique
type of slowly pulsating M-dwarf has been proposed. These unstable
M-dwarfs provide new laboratories in which to understand how changing
interior structures can produce potentially observable activity at the
surface. In this work, we report the results of the largest
high-resolution spectroscopic Hα emission survey to date
spanning this transition region, including 480 M-dwarfs observed using
the CHIRON spectrograph at CTIO/SMARTS 1.5m. We find that M dwarfs
with Hα in emission are almost entirely found 0-0.5mag above the
top edge of the gap in the HRD, whereas effectively no stars in and
below the gap show emission. Thus, the top edge of the gap marks a
relatively sharp activity transition, and there is no anomalous
Hα activity for stars in the gap. We also identify a new region
at 10.3<MG<10.8 on the main sequence where fewer M-dwarfs exhibit
Hα emission compared to M dwarfs above and below this magnitude
range. Careful evaluation of the results in the literature indicates
that (1) rotation and Hα activity distributions on the
main-sequence are closely related, and (2) fewer stars in this
absolute magnitude range rotate in less than ∼13days than populations
surrounding this region. This result suggests that the most massive
fully-convective stars lose their angular momentum faster than both
partially convective stars and less massive fully-convective stars.
Description:
We observed 443 of the 2249 stars using the CHIRON high-resolution
spectrograph on the SMARTS 1.5m telescope at Cerro Tololo
Inter-American Observatory (CTIO). Observations were made at the 1.5m
between 2018 November and 2022 August. Of the four different
resolutions available with CHIRON, 96% of the targets are observed in
the fiber mode with R=28000 that covers 4500-8300Å over 62 spectral
orders. The remaining targets were observed using slicer mode with
R=79000 covering the same wavelengths over 59 orders. All targets have
estimated V-magnitudes brighter than 15, so exposure times of
900-1800s were used, depending on brightness, to reach a mean
signal-to-noise ratio (S/N) of 23.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 93 2249 Selected M-dwarf targets close to the Gap
table4.dat 152 503 Results
--------------------------------------------------------------------------------
See also:
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
J/AJ/113/806 : M-Subdwarfs (Gizis 1997)
J/AJ/123/3356 : Palomar/MSU nearby star spectro survey. III. (Gizis+, 2002)
J/MNRAS/390/545 : Magnetic field & velocity of early M dwarfs (Donati+, 2008)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/AJ/141/97 : SDSS DR7 M dwarfs (West+, 2011)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/ApJ/795/161 : Activity & rotation in Praesepe & Hyades (Douglas+, 2014)
J/ApJ/788/81 : BANYAN III. RVel & rotation of low-mass stars (Malo+, 2014)
J/ApJ/812/3 : MEarth midtolate Mdwarfs rotation & kinematics (West+, 2015)
J/AJ/154/124 : M dwarfs-long-term photometric variability (Clements+, 2017)
J/ApJ/834/85 : Hα emission in nearby M dwarfs (Newton+, 2017)
J/MNRAS/475/1960 : ESPaDOnS spectropolarimeter obs. of M dwarfs (Fouque+, 2018)
J/AJ/156/140 : 4 eclipsing mid M-dwarf systems from MEarth (Irwin+, 2018)
J/A+A/614/A76 : CARMENES input catalogue of M dwarfs. III. (Jeffers+, 2018)
J/AJ/157/231 : MLSDSS-GaiaDR2 sample of M and L dwarfs (Kiman+, 2019)
J/ApJ/904/140 : Ruprecht 147 members & rot. data 5 other cl. (Curtis+, 2020)
J/A+A/635/A43 : Stellar rot periods from K2 Campaigns 0-18 (Reinhold+, 2020)
J/AJ/161/277 : Sample of 45 HαEW outliers (Kiman+, 2021)
J/ApJ/921/53 : IGRINS YSO survey. I. Tau-Aur (Lopez-Valdivia+, 2021)
J/AJ/162/176 : The solar neighborhood. XLVIII. (Paredes+, 2021)
J/ApJ/916/77 : K2 rot periods for SDSS & Gaia Mdwarfs (Popinchalk+, 2021)
J/ApJS/253/19 : Halpha and other EWs of LAMOST M-type stars (Zhang+, 2021)
J/AJ/163/257 : Properties of 125 Mdwarfs in southern CVZ (Anthony+, 2022)
J/AJ/164/251 : ZTF measured rotational per of 40553 M-G-dwarfs (Lu+, 2022)
J/AJ/163/278 : Stellar populations in IC 2602 and IC 2391 (Nisak+, 2022)
J/A+A/662/A41 : Magnetic fields in 292 M dwarfs. (Reiners+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia EDR3 identifier
21- 31 F11.7 deg RAdeg [0/360] Right Ascension (ICRS at Epoch=2016)
33- 42 F10.6 deg DEdeg [-86/87] Declination (ICRS at Epoch=2016)
44- 50 F7.3 mas plx [10/220] Gaia EDR3 parallax
52- 60 F9.3 mas/yr pmRA [-1222/1047] Gaia EDR3 proper motion in RA
62- 70 F9.3 mas/yr pmDE [-1666/796] Gaia EDR3 proper motion in DE
72- 75 F4.2 --- RUWE [0.79/1.4] Gaia EDR3 Renormalised Unit Weight Error
77- 81 F5.2 mag Gmag [8.03/15] Gaia EDR3 G-band magnitude
83- 87 F5.2 mag BPmag [9.39/17] Gaia EDR3 BP-band magnitude
89- 93 F5.2 mag RPmag [6.87/14] Gaia EDR3 RP-band magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia EDR3 identifier
21- 32 A12 --- objID Short Name used in this work
34- 35 I2 h RAh [0/23] Hour of Right Ascension
(ICRS at Epoch=2016)
37- 38 I2 min RAm Minute of Right Ascension (ICRS at Epoch=2016)
40- 44 F5.2 s RAs Second of Right Ascension (ICRS at Epoch=2016)
46- 46 A1 --- DE- [±] Sign of the Declination
(ICRS at Epoch=2016)
47- 48 I2 deg DEd Degree of Declination (ICRS at Epoch=2016)
50- 51 I2 arcmin DEm Arcminute of Declination (ICRS at Epoch=2016)
53- 57 F5.2 arcsec DEs Arcsecond of Declination (ICRS at Epoch=2016)
59- 66 F8.4 mas plx [13.8/202] Gaia EDR3 parallax
68- 71 F4.2 --- RUWE [0.79/1.4] Gaia EDR3 Renormalised Unit Weight
Error
73- 78 F6.3 mag Gmag [8.2/14] Gaia EDR3 G-band magnitude
80- 84 F5.3 --- BP-RP [2.4/2.6] Gaia EDR3 BP-RP color
86- 87 I2 --- NN [0/10] Number of neighbors
89- 89 I1 --- Nvisit [1/3] Number of observations
91- 96 A6 --- decker Spectra were taken with CHIRON in fiber or
slicer mode
98-106 F9.4 yr Epoch [2018/2023] Epoch or RVel, years
108-108 A1 --- Act [AE] Hα profile, A=absorption; E=emission
110-116 F7.2 km/s RVel [-139/104] Radial velocity
118-122 F5.2 km/s e_RVel [0.01/15] Uncertainty in RVel
124-128 F5.2 km/s vsini [10.1/21.3]? Projected rotational velocity
130-133 F4.2 km/s e_vsini [0.9/2]? Uncertainty in vsini
135-139 F5.2 0.1nm EW [-6.28/0.89] Equivalent width, Angstroms
141-144 F4.2 0.1nm e_EW [0.01/0.2] Uncertainty in EW
146-150 F5.3 --- CaH1 [0.15/1.16] CaH1 index
152-152 A1 --- binflag Binary flag, 1=possible binary
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Feb-2024