J/A+A/592/A156 The Solar Twin Planet Search. IV. (dos Santos+, 2016)
The Solar Twin Planet Search.
IV. The Sun as a typical rotator and evidence for a new rotational braking law
for Sun-like stars.
dos Santos L.A., Melendez J., do Nascimento J.-D.Jr, Bedell M.,
Ramirez I., Bean J.L., Asplund M., Spina L., Dreizler S., Alves-Brito A.,
Casagrande L.
<Astron. Astrophys. 592, A156 (2016)>
=2016A&A...592A.156D 2016A&A...592A.156D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, fundamental ; Stars, G-type ; Rotational velocities
Keywords: Sun: rotation - stars: solar-type - stars: rotation -
stars: fundamental parameters
Abstract:
It is still unclear how common the Sun is when compared to other
similar stars in regards to some of its physical properties, such as
rotation. Considering that gyrochronology relations are widely used
today to estimate ages of stars in the main sequence, and that the Sun
is used to calibrate it, it is crucial to assess whether these
procedures are acceptable. We analyze the rotational velocities,
limited by the unknown rotation axis inclination angle, of an
unprecedented large sample of solar twins to study the rotational
evolution of Sun-like stars, and assess whether the Sun is a typical
rotator. We used high-resolution (R=115000) spectra obtained with
the HARPS spectrograph and the 3.6m telescope at La Silla
Observatory. The projected rotational velocities for 81 solar twins
were estimated by line profile fitting with synthetic spectra.
Macroturbulence velocities were inferred from a prescription that
accurately reflects their dependence with effective temperature and
luminosity of the stars. Our sample of solar twins include some
spectroscopic binaries with enhanced rotational velocities, and we do
not find any nonspectroscopic binaries with unusually high rotation
velocities. We verified that the Sun does not have a peculiar
rotation, but the solar twins exhibit rotational velocities that
depart from the Skumanich relation. The Sun is a regular rotator when
compared to solar twins with a similar age. Additionally, we obtain a
rotational braking law that better describes the stars in our sample
(v∝t-0.6) in contrast to previous, often-used scalings.
Description:
Ages, the measured projected rotational velocities (vsini) and stellar
parameters of the 81 solar twins and the Sun. The ages of all solar
twins and stellar parameters for HIP68468 were obtained by Tucci Maia
et al. (2016A&A...590A..32T 2016A&A...590A..32T). Stellar parameters for the other solar
twins were obtained by Ramirez et al. (2014A&A...572A..48R 2014A&A...572A..48R). The vsini
were measured by line profile fitting using red spectra from HARPS
(R=115000). Macroturbulence velocities were inferred from the scaling
Eq. 2 in our study.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 81 82 Stellar ages, parameters and velocities
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Hipparcos Catalogue name and Sun
11- 15 F5.2 Gyr Age Stellar age
17- 20 F4.2 Gyr e_Age Error of the stellar age
22- 25 F4.2 km/s vsini Projected rotational velocity
27- 30 F4.2 km/s e_vsini Error of the projected rotational velocity
32- 37 F6.3 [-] [Fe/H] Metallicity
39- 43 F5.3 [-] e_[Fe/H] Error of the metallicity
45- 48 I4 K Teff Effective temperature
50- 51 I2 K e_Teff Error of the effective temperature
53- 56 F4.2 [cm/s2] logg Surface gravity
58- 61 F4.2 [cm/s2] e_logg Error of the surface gravity
63- 66 F4.2 km/s vt Microturbulence velocity
68- 71 F4.2 km/s e_vt Error of the microturbulence velocity
73- 76 F4.2 km/s vmacro Macroturbulence velocity
78- 81 A4 --- Note Specific note about the star (1)
--------------------------------------------------------------------------------
Note (1): Note as follows:
SS = stars belonging to the selected sample
SB I = single-lined spectroscopic binaries
--------------------------------------------------------------------------------
Acknowledgements:
Leonardo A. dos Santos, leonardoags(at)usp.br
References:
Ramirez et al., Paper I 2014A&A...572A..48R 2014A&A...572A..48R
Bedell et al., Paper II 2015A&A...581A..34B 2015A&A...581A..34B
Tucci Maia et al., Paper III 2016A&A...590A..32T 2016A&A...590A..32T
(End) Leonardo dos Santos [IAG-USP, Brazil], Patricia Vannier [CDS] 11-Jul-2016