J/ApJ/757/109 Rotational velocities + Li abundance in K giants (Carlberg+, 2012)
Observable signatures of planet accretion in red giant stars.
I. Rapid rotation and light element replenishment.
Carlberg J.K., Cunha K., Smith V.V., Majewski S.R.
<Astrophys. J., 757, 109 (2012)>
=2012ApJ...757..109C 2012ApJ...757..109C
ADC_Keywords: Abundances ; Stars, giant ; Rotational velocities
Keywords: stars: abundances; stars: atmospheres; stars: chemically peculiar;
stars: late-type; stars: rotation
Abstract:
The orbital angular momentum of a close-orbiting giant planet can be
sufficiently large that, if transferred to the envelope of the host
star during the red giant branch (RGB) evolution, it can spin-up the
star's rotation to unusually large speeds. This spin-up mechanism is
one possible explanation for the rapid rotators detected among the
population of generally slow-rotating red giant stars. These rapid
rotators thus comprise a unique stellar sample suitable for searching
for signatures of planet accretion in the form of unusual stellar
abundances due to the dissemination of the accreted planet in the
stellar envelope. In this study, we look for signatures of
replenishment in the Li abundances and (to a lesser extent)
12C/13C, which are both normally lowered during RGB evolution.
Accurate abundances were measured from high signal-to-noise echelle
spectra for samples of both slow and rapid rotator red giant stars. We
find that the rapid rotators are on average enriched in lithium
compared to the slow rotators, but both groups of stars have identical
distributions of 12C/13C within our measurement precision. Both of
these abundance results are consistent with the accretion of planets
of only a few Jupiter masses. We also explore alternative scenarios
for understanding the most Li-rich stars in our sample--particularly
Li regeneration during various stages of stellar evolution. Finally,
we find that our stellar samples show non-standard abundances even at
early RGB stages, suggesting that initial protostellar Li abundances
and 12C/13C may be more variable than originally thought.
Description:
We obtained spectra with S/N>100 per pixel for our K giant samples
using the echelle spectrographs on the Kitt Peak (KPNO) 4m Mayall
telescope (R∼22000) and the Apache Point Observatory (APO) 3.5m
telescope (R∼31500), between 2007 March and 2010 March. Between 2010
March and 2011 August, we obtained additional low S/N echelle spectra
of the rapid rotators. We detail our observations in Table 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 80 136 Observation log
table4.dat 80 91 Derived stellar parameters
table8.dat 53 90 A(Li) and 12C/13C of the program stars
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See also:
V/128 : Chromospherically Active Binaries. Third version (Eker+, 2008)
III/244 : Catalog of Stellar Rotational Velocities (Glebocki+ 2005)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
J/A+A/538/A36 : Lithium abundances of bulge RGB stars (Lebzelter+, 2012)
J/A+A/536/A71 : Atmospheric parameters of nearby giant stars (Jones+, 2011)
J/ApJ/732/39 : Rotational velocities of K giant stars (Carlberg+, 2011)
J/PASP/123/412 : Exoplanet Orbit Database (Wright+, 2011)
J/AJ/140/1911 : Astrometric Grid Giant Star Survey. II. (Bizyaev+, 2010)
J/A+A/503/541 : Neutral Li in late-type stars (Lind+, 2009)
J/A+A/502/267 : EWs of 31 giant stars of 10 open clusters (Smiljanic+, 2009)
J/AJ/135/209 : Rotational & RVs of HIP giants (Massarotti+, 2008)
J/A+A/475/1003 : Stellar parameters of G and K giant stars (Hekker+, 2007)
J/AJ/131/1784 : Astrometric Grid Giant Star Survey. I. (Bizyaev+, 2006)
J/ApJ/646/523 : Exoplanet systems with stellar companions (Raghavan+, 2006)
J/ApJ/646/505 : Catalog of nearby exoplanets (Butler+, 2006)
J/ApJ/636/821 : Abundances of Baade's Window K giants (Fulbright+, 2006)
J/A+A/430/165 : Radial velocities for 6691 K and M giants (Famaey+, 2005)
J/A+AS/142/275 : Stellar activity of late-type stars (Strassmeier+ 2000)
J/A+A/363/239 : Lithium abundances in single giant stars (De Medeiros+, 2000)
J/A+A/364/674 : Li-rich giants atomic lines (Castilho+, 2000)
J/A+AS/139/433 : RV and vsini of evolved stars (de Medeiros+ 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Set Set of stars (1)
6- 20 A15 --- Name Star name
22- 23 I2 h RAh Hour of right ascension (J2000)
25- 26 I2 min RAm Minute of right ascension (J2000)
28- 32 F5.2 s RAs Second of right ascension (J2000)
34 A1 --- DE- Sign of declination (J2000)
35- 36 I2 deg DEd Degree of declination (J2000)
38- 39 I2 arcmin DEm Arcminute of declination (J2000)
41- 42 I2 arcsec DEs Arcsecond of declination (J2000)
44- 47 F4.1 mag Vmag [/12.6] V-band magnitude
49 I1 --- Nexp Number of exposures
50 A1 --- --- [x]
51- 61 A11 s Texp Individual exposure time(s)
63- 66 A4 --- Obs Observatory (KPNO or APO)
68- 77 A10 "MM/DD/YYYY" Date Observation date
78 A1 --- --- [-]
79- 80 I2 --- Day ? Second day of observation
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Note (1): Set as follows:
slow = Slow rotators
fast = Rapid rotators
M08 = Massarotti et al. (2008, Cat. J/AJ/135/209) accretor candidates
Pl = Stars with planets
Ctrl = Control stars
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Stellar name (G1)
16 A1 --- --- [_]
17- 20 I4 yr Year ? Observation year (1)
21 A1 --- f_Teff [b] Adopted atmospheric parameters (2)
23- 26 I4 K Teff [4050/5170] Effective temperature
28- 31 F4.2 [cm/s2] log(g) [0.9/3.6] Logarithm of surface gravity (3)
33- 36 F4.2 [-] AFeI Mean abundance of FeI
38- 41 F4.2 [-] e_AFeI Standard deviation of AFeI
43- 44 I2 --- o_AFeI Number of FeI lines used to determine AFeI
46- 49 F4.2 [-] AFeII Mean abundance of FeII
51- 54 F4.2 [-] e_AFeII Standard deviation of AFeII
56- 57 I2 --- o_AFeII Number of FeII lines used to determine AFeII
59- 62 F4.2 km/s xi [0.5/3] Microturbulence velocity ξ
64- 68 F5.2 km/s vsini [0/30.4] Projected rotational velocity
70- 73 F4.2 km/s e_vsini [0/1] Error in vsini
75 I1 --- o_vsini [3/6] Number of lines from which vsini is
measured
77- 80 F4.2 km/s zeta [2/7.2] Macroturbulence velocity ζ
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Note (1): The Teff, log(g), AFeI, e_AFeI, o_AFeI, AFeII, e_AFeII, o_AFeII,
and xi values for Arcturus_2007, Tyc5904-00513-1_2007, and
Tyc6094-01204-1_2008 were adopted from the measurements made in
Arcturus_2008, Tyc5904-00513-1_2008, and Tyc6094-01204-1_2007,
respectively and were not remeasured. The vsini, e_vsini, N_vsini, and
zeta for G0928+73.2600_2008 were adopted from the measurement made in
the G0928+73.2600_2007 spectrum.
Note (2):
b = The Teff, log(g), AFeI, and xi for HD31993 (second solution) were
adopted from Castilho et al. (2000, Cat. J/A+A/364/674).
Note (3): The high log(g) of G0827-16.3424 necessitated the use of Kurucz
plane-parallel models.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Stellar name (G1)
16 A1 --- --- [_]
17- 20 I4 yr Year ? Observation year
21 A1 --- n_ALi-L [ab] Note on ALi derivation (4)
23- 27 F5.2 [-] ALi-L [-2/3.7]? LTE lithium abundance
29- 32 F4.2 [-] s_ALi-L ? δA(Li), uncertainty due to the choice
of what constitutes the best fit
34- 37 F4.2 [-] e_ALi-L ? Total error in A(Li)
39- 43 F5.2 [-] ALi-N [-1.9/3.3]? NLTE lithium abundance
45- 48 F4.1 --- 12/13C [6.9/40.3]? Number ratio of 12C to 13C
50- 53 F4.1 --- e_12/13C ? Uncertainty in the 12C/13C
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Note (4): Flag as follows:
a = See Carlberg et al. (2010ApJ...723L.103C 2010ApJ...723L.103C) for details of the ALi and
Cratio measurement for G0928+73.2600.
b = The second solution for HD31993 were derived using stellar parameters
adopted from Castilho et al. (2000, Cat. J/A+A/364/674).
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Global notes:
Note (G1): Star "G1130+37.9414" in tables 4 and 8 (and in Figure 9) is very
likely a misprint for "G1130+39.9414"; corrected in the CDS tables.
See also "G1130+39.9414" in Cat. J/ApJ/732/39.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-May-2014