J/ApJ/901/91 Sp. obs. of rapidly rotating stars in the Pleiades (Torres, 2020)
Spectroscopic monitoring of rapidly rotating early-type stars in the Pleiades
cluster.
Torres G.
<Astrophys. J., 901, 91 (2020)>
=2020ApJ...901...91T 2020ApJ...901...91T
ADC_Keywords: Radial velocities; Stars, early-type; Binaries, spectroscopic;
Rotational velocities; Spectral types; Optical
Keywords: Open star clusters ; Binary stars ; Spectroscopic binary stars ;
Visual binary stars ; Radial velocity ; Stellar rotation
Abstract:
Radial velocities for the early-type stars in the Pleiades cluster
have always been challenging to measure because of the significant
rotational broadening of the spectral lines. The large scatter in
published velocities has led to claims that many are spectroscopic
binaries, and in several cases, preliminary orbital solutions have
been proposed. To investigate these claims, we obtained and report
here velocity measurements for 33 rapidly rotating B, A, and early F
stars in the Pleiades region, improving significantly on the precision
of the historical velocities for most objects. With one or two
exceptions, we do not confirm any of the previous claims of
variability, and we also rule out all four of the previously published
orbital solutions, for HD 22637, HD 23302, HD 23338, and HD 23410. We
do find HD 22637 to be a binary but with a different period (71.8d).
HD 23338 is likely a binary as well, with a preliminary 8.7yr period
also different from the one published. Additionally, we report a 3635d
orbit for HD 24899, another new spectroscopic binary in the cluster.
From the 32 bona fide members in our sample, we determine a mean
radial velocity for the Pleiades of 5.79±0.24km/s, or
5.52±0.31km/s when objects with known visual companions are
excluded. Adding these astrometric binaries to the new spectroscopic
ones, we find a lower limit to the binary fraction among the B and A
stars of 37%. In addition to the velocities, we measure vsini for
all stars, ranging between 69 and 317km/s.
Description:
Spectroscopic monitoring of the B, A, and F stars in our sample was
carried out between 2009 October and 2020 January with the Tillinghast
Reflector Echelle Spectrograph (TRES) attached to the 1.5m Tillinghast
Reflector at the Fred L. Whipple Observatory on Mount Hopkins (AZ). It
delivers a resolving power of R∼44000 and covers the wavelength region
of 3800-9100Å in 51 orders. We collected a total of 388 spectra for
our list of 33 stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 33 Stars in our sample and rotational velocities
table2.dat 31 388 Heliocentric radial velocity measurements
table3.dat 93 33 Summary of radial velocity results
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)
II/131 : Tonantzintla Pleiades Flare Stars (Haro+ 1982)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
III/279 : RAVE 5th data release (Kunder+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/320/74 : Radial velocities of Pleiades members (Mermilliod+ 1997)
J/A+A/329/101 : Masses of Pleiades members (Raboud+ 1998)
J/A+AS/144/469 : Delta Scuti stars (Rodriguez+, 2000)
J/A+A/368/912 : Polarization & rot. velocities of Be stars (Yudin, 2001)
J/ApJ/573/359 : Rotational velocities of B stars from BSC (Abt+, 2002)
J/AJ/124/1144 : Orbits of 171 single-lined sp. binaries (Latham, 2002)
J/A+A/393/897 : Rotational velocities of A-type stars II. (Royer+, 2002)
J/A+A/440/305 : Fundamental param. of fast-rotating B stars (Fremat+, 2005)
J/AJ/129/2420 : Proper motion derivatives of binaries (Makarov+, 2005)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/A+A/498/949 : Veloc. of F-K dwarfs in open clusters (Mermilliod+, 2009)
J/MNRAS/424/1925 : Spectrocopic Binarity of O and B type stars (Chini+, 2012)
J/other/A+ARV/20.51 : Rapidly rotating stars (Van Belle, 2012)
J/A+A/537/A120 : Rotational velocities of A-type stars. IV. (Zorec+, 2012)
J/MNRAS/458/2307 : gamma Dor stars sp. survey (Kahraman Alicavus+, 2016)
J/A+A/595/A132 : Be star rotational velocities distribution (Zorec+, 2016)
J/A+A/597/A22 : Massive O- and B-type stars velocities (Simon-Diaz+, 2017)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diag. (Gaia Collaboration, 2018)
J/A+A/623/A72 : Binarity of HIP stars from Gaia pm anomaly (Kervella+, 2019)
J/AJ/157/196 : Close companions around young stars (Kounkel+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 19 A10 --- OName Other name
21- 22 I2 h RAh Hour of right ascension (J2000)
24- 25 I2 min RAm Minute of right ascension (J2000)
27- 31 F5.2 s RAs Second of right ascension (J2000)
33 A1 --- DE- Sign of declination (J2000)
34- 35 I2 deg DEd Degree of declination (J2000)
37- 38 I2 arcmin DEm Arcminute of declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of declination (J2000)
45- 50 A6 --- SpT Spectral type from SIMBAD
52- 54 I3 km/s vsini Rotational velocity from this work from Table 6
56- 57 I2 km/s e_vsini Vsini uncertainty
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 19 F10.4 d HJD [55107/58894.7] Heliocentric Julian Date;
HJD-2400000
21- 26 F6.2 km/s RVel [-19.99/19.6] Radial velocity
28- 31 F4.2 km/s e_RVel [0.32/6.74] Uncertainty in RVel
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Main name of the source
10 A1 --- f_Name [*] * = see notes in the text
12- 13 I2 --- Nobs [5/32] Number of observations
15- 17 I3 --- S/N [54/352] Average signal-to-noise ratio
per resolution element
19- 23 I5 d HJD1 Heliocentric Julian Date start of observation;
HJD1-2400000
24 A1 --- --- [-]
25- 29 I5 d HJD2 Heliocentric Julian Date end of observation
HJD2-2400000
31- 34 I4 d Span [324/3394] Time span
36- 39 F4.2 km/s RV [3.78/9.41] Average radial velocity,
41- 44 F4.2 km/s e_RV [0.07/2.8] standard deviation of the velocity (1)
46- 49 F4.2 --- RVp [4.2/7.2]? Predicted radial velocity (2)
51- 56 F6.4 arcsec Sep [0.0019/3.5]? Angular separation of the pair
57 A1 --- f_Sep [*] Flag on Sep (3)
58 A1 --- --- [,]
60- 62 F3.1 mag Dmag [0/6.1]? Magnitude difference of the pair
64 I1 --- Bin [1/8]? Binarity reference (4)
66- 93 A28 --- Lit Velocity variability from the literature or
published orbital solutions (5)
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Note (1): The standard deviation of the velocities for each star
which we adopt here as the error of the mean velocity, to be
conservative.
For HD 22637, HD 23338, and HD 24899, the velocities and uncertainties
listed correspond to the center-of mass velocity of the binary, based
on the new orbital solutions in this paper (Tables 4 and 5).
Note (2): The predicted radial velocity, RVpred, within the cluster, based
on the position of the convergent point and the mean distance and
proper motion of the Pleiades from the Gaia mission
(Gaia Col.+ 2018A&A...616A...1G 2018A&A...616A...1G ; see I/345).
It is not given for HD 24013, which is a background star and not a
cluster member.
Uncertainties for the predicted velocities are very small (<0.1km/s).
Note (3): Flag for the close astrometric binaries as follows:
* = the measurement is from a lunar occultation event, in which case
it corresponds strictly to a separation projected in the direction
of the lunar motion.
Note (4): Reference for the close astrometric binaries as follows:
1 = Washington Double Star Catalog (Mason+ 2001AJ....122.3466M 2001AJ....122.3466M ; Cat. B/wds);
2 = Richichi et al. (2002A&A...382..178R 2002A&A...382..178R);
3 = Richichi et al. (1994A&A...286..829R 1994A&A...286..829R);
4 = Guerrero et al. (2020MNRAS.495..806G 2020MNRAS.495..806G);
5 = McGraw et al. (1974AJ.....79.1299M 1974AJ.....79.1299M);
6 = Richichi et al. (2012A&A...541A..96R 2012A&A...541A..96R);
7 = Qian & Fan (1991AcASn..32..103Q 1991AcASn..32..103Q);
8 = ESA (1997, I/239)
Note (5): Previous claims of velocity variability from the literature ("var"),
or published orbital solutions ("orb"). Codes in parentheses are:
F = Frost et al. (1926ApJ....64....1F 1926ApJ....64....1F);
S = Smith & Struve (1944ApJ...100..360S 1944ApJ...100..360S);
A = Abt et al. (1965ApJ...142.1604A 1965ApJ...142.1604A);
H = Hube (1970MmRAS..72..233H 1970MmRAS..72..233H);
P = Pearce & Hill (1971PASP...83..493P 1971PASP...83..493P);
P1 = Pearce & Hill (1975PDAO...14..319P 1975PDAO...14..319P);
J = Jarad et al. (1989MNRAS.238.1085J 1989MNRAS.238.1085J);
L = Liu et al. (1991ApJ...377..141L 1991ApJ...377..141L).
The three objects with new orbits from this work are also noted.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Jan-2022