2008ApJ...684.1390R


Query : 2008ApJ...684.1390R

2008ApJ...684.1390R - Astrophys. J., 684, 1390-1403 (2008/September-2)

Chromospheric activity, rotation, and rotational braking in M and L dwarfs.

REINERS A. and BASRI G.

Abstract (from CDS):

We present results from a high-resolution spectroscopic survey of 45 L dwarfs, which includes both very low mass stars and brown dwarfs. Our spectra allow us to derive a significant number of new rotational velocities, and discover a slowly rotating (in projected velocity) L dwarf that allows more accurate measurement of spectroscopic rotations for these objects. We measure chromospheric activity (and often its variability) through the Hα emission line. Our primary new result is good evidence that magnetic braking dominates the angular momentum evolution of even brown dwarfs, although spindown times appear to increase as mass decreases. We confirm that activity decreases as effective temperature decreases, although a larger fraction of L dwarfs are active than has previously been reported. Essentially all active objects are also variable. We confirm the lack of a rotation-activity connection for L dwarfs. We find a minimum limit for rotational velocities that increases with later spectral types, rising from near zero in older mid-M stars to more than 20 km/s for mid-L objects. There is strong evidence that all L dwarfs are rapid rotators. We derive a braking law that can depend on either temperature or mass which can explain all the rotational results and provides an age dependence for the angular momentum evolution. It is clear that angular momentum loss mechanisms in smaller and cooler objects become more inefficient, starting at the fully convective boundary.

Abstract Copyright:

Journal keyword(s): Stars: Activity - Stars: Flare - Stars: Late-Type - Stars: Low-Mass, Brown Dwarfs - Stars: Rotation

Simbad objects: 51

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Number of rows : 51
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 L 362-29 B BD* 00 04 34.8641153471 -40 44 06.464450691       19.61 16.88 L5+L5 96 0
2 LP 881-64 ** 00 24 44.220360 -27 08 25.04904   17.18 15.338 13.502 11.403 M5.5/6Ve+M8.5Ve+M9/9.5V 125 0
3 LSPM J0036+1821 BD* 00 36 16.1119130763 +18 21 10.291990145       18.451 16.053 L3.5 190 0
4 2MASS J01443536-0716142 BD* 01 44 35.4046436342 -07 16 14.314061744           L6.5 43 0
5 HD 16270B BD* 02 35 59.9393683632 -23 31 20.398833102           L1.5 36 0
6 DENIS J025503.3-470049 BD* 02 55 03.6945042584 -47 00 51.345365454     22.921 19.906 17.454 L9 127 0
7 2MASS J03140344+1603056 BD* 03 14 03.4419804524 +16 03 05.475765117           L0 25 0
8 2MASS J05233822-1403022 BD* 05 23 38.2238597336 -14 03 02.008934344           L2.5 52 0
9 2MASS J05325346+8246465 BD* 05 32 54.4385958315 +82 46 45.174215154           esdL7 55 0
10 LSPM J0602+3910 BD* 06 02 30.4676218461 +39 10 58.586394260       19.0   L1V 36 0
11 2MASS J07003664+3157266 BD* 07 00 36.7166853497 +31 57 25.503841463           L3+L6.5 34 0
12 LSPM J0746+2000 BD* 07 46 42.50553 +20 00 31.9757       17.9 15.034 L0+L1.5 174 1
13 2MASSI J0825196+211552 BD* 08 25 19.6171008398 +21 15 51.565129705       21.97 19.22 L7.5V 107 0
14 SSSPM J0829-1309 BD* 08 28 34.1713208171 -13 09 19.842042734         16.07 L2 42 0
15 2MASS J08354256-0819237 BD* 08 35 42.5323299335 -08 19 23.389468248           L6.5 58 0
16 2MASS J09130320+1841501 BD* 09 13 03.20736 +18 41 50.1432           L3V 19 0
17 2MASS J09211410-2104446 BD* 09 21 14.1078049422 -21 04 44.422366157         16.50 L1 37 0
18 2MASS J10224821+5825453 BD* 10 22 48.2222984613 +58 25 45.394831331           L0.6V 35 0
19 2MASSI J1029216+162652 BD* 10 29 21.7025023848 +16 26 51.888202233       19.588 17.600 L2.5 29 0
20 2MASS J10452400-0149576 BD* 10 45 23.9817721466 -01 49 57.766480663       18.797 16.509 L1 35 0
21 DENIS J104731.1-181558 BD* 10 47 31.0598687732 -18 15 57.451257015           L0.3V 24 0
22 LSPM J1048+0111 BD* 10 48 42.8148643194 +01 11 58.221459212       19.4   L1 42 0
23 2MASSW J1145572+231730 BD* 11 45 57.1438962445 +23 17 29.652833703           L1.5V 27 0
24 2MASS J11553952-3727350 BD* 11 55 39.5360387792 -37 27 35.506067298           L2e 34 0
25 2MASS J11593850+0057268 BD* 11 59 38.4887250057 +00 57 26.694904747           L0.4V 25 0
26 2MASS J12035812+0015500 BD* 12 03 58.1325905721 +00 15 50.108788052           L5.0V 30 1
27 2MASS J12212770+0257198 BD* 12 21 27.7131144739 +02 57 19.771565458           L0.5 30 0
28 2MASSI J1300425+191235 BD* 13 00 42.5078338130 +19 12 34.600170519         15.9 L1.7V 47 0
29 NAME Kelu-1 BD* 13 05 40.1737206066 -25 41 05.830344467         16.85 L2+L3.5 241 0
30 2MASS J13153094-2649513 BD* 13 15 30.8602676392 -26 49 51.844923573           L5e 39 1
31 2MASS J13340623+1940351 BD* 13 34 06.2109918165 +19 40 35.210886869           L1.5V 18 0
32 2MASS J13595510-4034582 BD* 13 59 55.1138685185 -40 34 58.515416266         16.985 L3.1:V 18 0
33 2MASSW J1412244+163312 BD* 14 12 24.4909214617 +16 33 11.741214448       19.449 17.258 L0.5V 24 0
34 2MASS J14392836+1929149 BD* 14 39 28.36896 +19 29 14.9820           L1V 119 0
35 DENIS J144137.2-094558 BD* 14 41 37.1670168475 -09 45 59.155474431       20.030 17.234 L1+L1 48 0
36 2MASSW J1506544+132106 BD* 15 06 54.3298685056 +13 21 06.041740524           L3 85 0
37 2MASSW J1507476-162738 BD* 15 07 47.6756748763 -16 27 40.118410414     22.136 18.928 16.579 L5V 176 0
38 2MASS J15551573-0956055 BD* 15 55 15.7768703009 -09 56 06.044492616           L1.6V 26 0
39 LSR J1610-0040 LM* 16 10 28.9562440851 -00 40 53.300190959       17.51 14.81 sdM6.5 48 0
40 2MASSW J1615441+355900 BD* 16 15 44.1549648987 +35 58 59.562297891           L3V 28 0
41 2MASS J16452211-1319516 BD* 16 45 22.0919780729 -13 19 52.262593548           L1.5 32 0
42 2MASS J17054834-0516462 BD* 17 05 48.3507836186 -05 16 46.341214454         16.55 L1 37 0
43 LSPM J1731+2721 BD* 17 31 29.7424764159 +27 21 23.234590972   20.1   17.6 14.9 L0 35 0
44 2MASS J18071593+5015316 BD* 18 07 15.9376984448 +50 15 31.634072578           L1 36 0
45 G 227-29 PM* 18 22 27.14136 +62 03 01.9512   14.8   12.2   M4.0V 70 0
46 2MASS J18544597+8429470 LM* 18 54 45.8769760993 +84 29 46.954649370           M9 10 0
47 2MASS J20575409-0252302 BD* 20 57 54.0935087240 -02 52 30.249848091           L1 52 0
48 2MASS J21041491-1037369 BD* 21 04 14.9650744184 -10 37 37.345297509           L2 44 0
49 2MASS J22000201-3038327 ** 22 00 02.01888 -30 38 32.7120       19.2 16.7 M9+L0 28 0
50 2MASSW J2224438-015852 BD* 22 24 43.8550503291 -01 58 53.265872547           L4.5V 110 0
51 SSSPM J2352-2538 LM* 23 51 50.4655324606 -25 37 36.839115132           M9e 34 0

    Equat.    Gal    SGal    Ecl

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2021.07.26-06:12:22

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