J/AJ/143/134 Candidate members of β Pic / AB Dor groups (McCarthy+, 2012)
The sizes of the nearest young stars.
McCarthy K., White R.J.
<Astron. J., 143, 134 (2012)>
=2012AJ....143..134M 2012AJ....143..134M
ADC_Keywords: Stars, double and multiple ; Photometry, UBV ; Spectral types
Effective temperatures ; Equivalent widths
Keywords: binaries: general - stars: fundamental parameters -
stars: pre-main sequence - techniques: interferometric
Abstract:
We present moderate resolution (R∼3575) optical spectra of 19 known or
suspected members of the AB Doradus and β Pictoris Moving Groups,
obtained with the DeVeny Spectrograph on the 72inch Perkins telescope
at Lowell Observatory. For four of five recently proposed members,
signatures of youth such as LiI 6708Å absorption and Hα
emission further strengthen the case for youth and membership. The
lack of detected lithium in the proposed β Pic member
TYC 2211-1309-1 implies that it is older than all other K-type members
and weakens the case for membership. Effective temperatures are
determined via line ratio analyses for the 11 F, G, and early-K stars
observed, and via spectral comparisons for the eight late-K and M
stars observed. We assemble updated candidate membership lists for
these moving groups that account for known binarity. Currently, the AB
Dor Moving Group contains 127 proposed members and the β Pic
Moving Group holds 77 proposed members. We then use temperature,
luminosity, and distance estimates to predict angular diameters for
these stars; the motivation is to identify stars that can be spatially
resolved with long-baseline optical/infrared interferometers in order
to improve age estimates for these groups and to constrain
evolutionary models at young ages. Considering the portion of the sky
accessible to northern hemisphere facilities (DE>-30), six stars have
diameters large enough to be spatially resolved (θ>0.4mas) with
the CHARA Array, which currently has the world's longest baseline of
331m; this subsample includes the low-mass M2.5 member of AB Dor, GJ
393, which is likely to still be pre-main sequence. For southern
hemisphere facilities (DE<+30), 18 stars have diameters larger than
this limiting size, including the low-mass debris disk star AU Mic
(0.72mas). However, the longest baselines of southern hemisphere
interferometers (160m) are only able to resolve the largest of these,
the B6 star α Gru (1.17mas); proposed long-baseline stations may
alleviate the current limitations.
Description:
The majority of the AB Doradus and β Pictoris Moving Group
members come from the compilation paper of Torres et al.
(2008hsf2.book..757T 2008hsf2.book..757T). For the AB Doradus Moving Group, we added the
six proposed members from Schlieder et al. (2010, Cat. J/AJ/140/119),
three candidate members from da Silva et al. (2009, Cat.
J/A+A/508/833), and seven candidates from Zuckerman et al.
(2011ApJ...732...61Z 2011ApJ...732...61Z). Lepine & Simon (2009AJ....137.3632L 2009AJ....137.3632L), Schlieder
et al. (2010, Cat. J/AJ/140/119), and Kiss et al. (2011MNRAS.411..117K 2011MNRAS.411..117K)
have identified another 13 candidate members of the β Pictoris
Moving Group which we include in our sample.
We obtained moderate resolution optical spectra of 19 stars in the
β Pic and AB Dor Moving Groups (Table 3). All observations were
obtained with the DeVeny spectrograph on the Perkins 72inch Telescope
at the Lowell Observatory during three observing runs: 2009 February
5, 2009 May 7, and 2009 August 1-3. The resulting spectra had a
resolution of ∼3575.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 125 127 Proposed AB Doradus moving group members
table2.dat 129 77 Proposed β Pictoris moving group members
table3.dat 59 19 LiI and Hα equivalent widths
refs.dat 62 11 References
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See also:
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
J/AJ/140/119 : βPic and AB Dor moving groups members (Schlieder+, 2010)
J/A+A/508/833 : SACY III. Li abundances (Da Silva+, 2009)
J/ApJ/683/424 : CHARA observations of 3 late-type stars (Boyajian+, 2008)
J/ApJ/670/1367 : Gemini Deep Planet Survey (Lafreniere+, 2007)
J/A+A/460/695 : Search for Associations Containing Young stars (Torres+, 2006)
J/A+A/433/151 : Spectrocopic result on ROSAT late-type stars (Zickgraf+, 2005)
J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)
J/AJ/126/2048 : NStars project: the Northern Sample. I. (Gray+, 2003)
J/A+AS/145/67 : Double stars measurements (Morlet+, 2000)
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD ? HD identifier
8- 9 A2 --- m_HD HD component (A, Aa, Ab, B, Ba, Bb or C)
11- 16 I6 --- HIP ? HIP identifier (from Cat. I/239)
18- 19 A2 --- m_HIP HIP component (A, Aa, Ab, B, Ba, Bb or C)
21- 41 A21 --- OName Other name (1)
43 A1 --- n_Dist [*Hc] Method used to derive Dist (2)
44- 49 F6.2 pc Dist [7.23/143] Heliocentric distance
51 A1 --- f_Vmag [d] possible bias due to unseen companion (3)
52- 57 F6.3 mag Vmag [1.7/14.8]? Johnson V-band magnitude
59 A1 --- f_Ksmag [d] possible bias due to unseen companion (3)
60- 64 F5.2 mag Ksmag [2.02/12.72]? 2MASS Ks-band magnitude
66 A1 --- f_SpT1 [:] spectral type estimated from photometry (4)
67- 70 A4 --- SpT1 Previous MK spectral type
72- 76 I5 K Teff1 ? Previous effective temperature
78- 81 A4 --- SpT2 New MK spectral type
83- 86 I4 K Teff2 ? New effective temperature (see Section 4.3)
88 A1 --- f_L [d] possible bias due to unseen companion (3)
89- 95 F7.3 Lsun L ? Bolometric luminosity
97 A1 --- f_theta [d] possible bias due to unseen companion (3)
98-101 F4.2 mas theta ? Angular size θ (see Section 5)
103-106 A4 --- Mult Multiplicity status of the star, if known
(S=single, B=binary, T=triple or Q=quadruple)
108-112 F5.2 arcsec Sep ? Projected separation for multiple star
(if the pair has been spatially resolved)
114-129 A16 --- Ref Multiplicity reference (in refs.dat file)
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Note (1): In Table 2, CD-15 7414 is a misprint for CD-53 7414
(corrected at the CDS).
Note (2): Flag as follows:
* = Distance assumed to be that of their companion.
H = Distance from Hipparcos parallax (van Leeuwen, 2007, Cat. I/311).
c = Distance calculated based on an assumed radius (see Section 2).
Note (3):
d = measurements that may be biased by a spatially unresolved companion.
Note (4):
: = Spectral type estimated from B-V color (see Section 2).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HD ? HD identifier
8- 13 I6 --- HIP ? Hipparcos identifier (from Cat. I/239)
15- 35 A21 --- OName Other name (1)
37- 40 A4 --- Run Observational run (5=observed during the
May run, 8=observed during the August run)
42- 44 I3 --- S/N [40/350] Signal-to-noise ratio estimates
46 A1 --- l_W(Li) Upper limit in EWLi
47- 50 F4.2 0.1nm W(Li) Equivalent widths of LiI 6708Å
52- 56 F5.2 0.1nm W(Ha) Equivalent widths of Hα
58- 59 A2 --- Group Moving group (AB=AB Doradus, bP=βPictoris)
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Note (1): 1RXS J19506.8-3320720 is a misprint for 1RXS J195602.8-320720
(corrected as the CDS).
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Ref Reference identifier
6- 24 A19 --- BibCode BibCode
26- 42 A17 --- Aut Author's name
44- 62 A19 --- Com Comments
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History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 05-Jul-2013