J/AJ/154/191 The solar neighborhood. XLII. New nearby subdwarfs (Jao+, 2017)
The solar neighborhood.
XLII. Parallax results from the CTIOPI 0.9 m program-identifying new nearby
subdwarfs using tangential velocities and locations on the H-R diagram.
Jao W.-C., Henry T.J., Winters J.G., Subasavage J.P., Riedel A.R.,
Silverstein M.L., Ianna P.A.
<Astron. J., 154, 191 (2017)>
=2017AJ....154..191J 2017AJ....154..191J (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Stars, subdwarf ; Parallaxes, trigonometric ;
Proper motions ; Photometry, VRI ; Photometry, infrared ;
Spectral types
Keywords: astrometry - solar neighborhood - stars: distances -
stars: low-mass - subdwarfs
Abstract:
Parallaxes, proper motions, and optical photometry are presented for
51 systems consisting of 37 cool subdwarf and 14 additional high
proper motion systems. Thirty-seven systems have parallaxes reported
for the first time, 15 of which have proper motions of at least 1"/yr.
The sample includes 22 newly identified cool subdwarfs within 100 pc,
of which three are within 25 pc, and an additional five subdwarfs from
100 to 160 pc. Two systems-LSR 1610-0040 AB and LHS 440 AB-are close
binaries exhibiting clear astrometric perturbations that will
ultimately provide important masses for cool subdwarfs. We use the
accurate parallaxes and proper motions provided here, combined with
additional data from our program and others, to determine that
effectively all nearby stars with tangential velocities greater than
200 km/s are subdwarfs. We compare a sample of 167 confirmed cool
subdwarfs to nearby main sequence dwarfs and Pleiades members on an
observational Hertzsprung-Russell diagram using MV versus (V-Ks) to
map trends of age and metallicity. We find that subdwarfs are clearly
separated for spectral types K5-M5, indicating that the low metallicities
of subdwarfs set them apart in the H-R diagram for (V-Ks)=3-6. We
then apply the tangential velocity cutoff and the subdwarf region of
the H-R diagram to stars with parallaxes from Gaia Data Release 1 and
the MEarth Project to identify a total of 29 new nearby subdwarf
candidates that fall clearly below the main sequence.
Description:
We used the CTIO/SMARTS 0.9 m to measure parallaxes and optical photometry
in the VRI filters. The telescope has a 2048x2046 Tektronix CCD camera
with 0.401"/pixel plate scale (Jao et al. 2005AJ....129.1954J 2005AJ....129.1954J). For both
astrometric and photometric observations, we used the central quarter
of the chip, yielding a 6.8' square field of view. We used the Johnson V
and Kron-Cousins RI filters for parallax measurements to maximize the
number of suitable reference stars in the field; because of their
relative faintness, 31 of the 51 systems were observed in the I band.
For the 51 systems discussed here, astrometric series spanned 2-15 years
with a median of 5 years.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 144 54 Astrometry Results
table2.dat 112 55 Photometry and Spectroscopy Results
table4.dat 106 51 Subdwarf Candidates Selected from MEarth
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See also:
III/119 : Spectral classifications of proper motion stars (Bidelman+ 1985)
III/198 : Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/PASP/109/849 : Probing the LHS Catalog (Gizis+ 1997)
J/AJ/123/2828 : Spectroscopy of northern NLTT stars (Cruz+, 2002)
J/AJ/125/1598 : New high proper motion stars in the northern sky
(Lepine+, 2003)
J/AJ/126/2449 : Nearby ultracool dwarfs in galactic plane (Reid+, 2003)
J/AJ/128/463 : A preliminary 20pc census from the NLTT catalogue
(Reid+, 2004)
J/A+A/442/211 : Spectroscopic distances of 322 NLTT stars (Scholz+, 2005)
J/AJ/129/413 : New high proper motion stars (-90<DE←47)
(Subasavage+, 2005)
J/AJ/130/1658 : New high proper motion stars (-47<δ<00)
(Subasavage+, 2005)
J/PASP/117/676 : LHS faint proper-motion stars (Reid+, 2005)
J/MNRAS/373/705 : Optical spectroscopy of high proper motion stars
(Reyle+, 2006)
J/AJ/133/2524 : Spectra of young nearby stars (White+, 2007)
J/AJ/133/2825 : Star beyond the NLTT catalog (Reid+, 2007)
J/AJ/133/2898 : New proper-motion stars (-90<DE< -47) (Finch+, 2007)
J/AJ/134/252 : New nearby white dwarf systems (Subasavage+, 2007)
J/AJ/141/21 : CCD distance estimates of SCR targets (Winters+, 2011)
J/AJ/142/10 : New proper motion stars 0.40"/yr>pm≥0.18"/yr (Boyd+, 2011)
J/AJ/142/92 : New proper motion stars with pm≥0.18"/yr (Boyd+, 2011)
J/AJ/144/64 : Solar neighborhood. XXVIII. Substellar companions
(Dieterich+, 2012)
J/AJ/147/85 : Solar neighborhood. XXXIII. 45 M dwarfs (Riedel+, 2014)
J/AJ/147/94 : Solar neighborhood. XXXII. L and M dwarfs
(Dieterich+, 2014)
J/ApJ/784/156 : Parallaxes for 1507 nearby mid-to-late M dwarfs
(Dittmann+, 2014)
J/A+A/577/A128 : CARMENES input catalogue of M dwarfs. I
(Alonso-Floriano+, 2015)
J/AJ/149/5 : Solar neighborhood. XXXV. Distances to M dwarfs
(Winters+, 2015)
J/AJ/150/6 : Solar neighborhood. XXXVI. VRI variability of M dwarfs
(Hosey+, 2015)
J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs
(Benedict+, 2016)
J/other/RAA/16.G7 : Nearby M subdwarfs from LAMOST DR2 (Bai+, 2016)
J/AJ/153/14 : Solar neighborhood XXXVIII. Nearby M dwarf systems
(Winters+, 2017)
J/AJ/154/32 : Solar neighborhood. XXXIX. Nearby white dwarfs
(Subasavage+, 2017)
J/AJ/154/124 : M dwarfs-long-term photometric variability
(Clements+, 2017)
J/AJ/154/151 : The solar neighborhood .XXXX. New young stars
(Bartlett+, 2017)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Type Parallax type (1)
9- 23 A15 --- Name Source identifier
25- 26 I2 h RAh ? Hour of Right Ascension (J2000)
28- 29 I2 min RAm ? Minute of Right Ascension (J2000)
31- 35 F5.2 s RAs ? Second of Right Ascension (J2000)
37 A1 --- DE- Sign of the Declination (J2000)
38- 39 I2 deg DEd ? Degree of Declination (J2000)
41- 42 I2 arcmin DEm ? Arcminute of Declination (J2000)
44- 47 F4.1 arcsec DEs ? Arcsecond of Declination (J2000)
49 A1 --- Filter [VRI ] Filter used
51- 52 I2 --- Nsea [3/12]? Number of seasons observed (2)
53 A1 --- f_Nsea [cs] Flag on Nsea (3)
55- 57 I3 --- Nfrm [27/177]? Number of frames used in reductions
59- 65 F7.2 yr Start [1999.5/2011.5]? Start of observational coverage
67- 73 F7.2 yr End [2003.25/2016.47]? End of observational coverage
75- 79 F5.2 --- Nyr [2.17/14.99]? Number of years of coverage
81- 82 I2 --- Nref [6/13]? Number of reference stars
84- 88 F5.2 mas Rplx [3.38/87.06]? Relative parallax
90- 93 F4.2 mas e_Rplx [0.46/2.54]? Uncertainty in Rplx
95- 98 F4.2 mas Cplx [0.31/4.27]? Parallax correction
100-103 F4.2 mas e_Cplx [0.02/0.9]? Uncertainty in Cplx
105-109 F5.2 mas Aplx [3.87/88.66]? Absolute parallax
111-114 F4.2 mas e_Aplx [0.48/2.61]? Uncertainty in Aplx
116-121 F6.1 mas/yr pm [182.1/3495.1]? Proper motion
123-125 F3.1 mas/yr e_pm [0.2/2.8]? Uncertainty in pm
127-131 F5.1 deg PA [9/324.8]? Position angle of proper motion
133-136 F4.2 deg e_PA [0.01/0.85]? Uncertainty in PA
138-142 F5.1 km/s Vtan [41.9/486.5]? Derived tangential velocity
144 A1 --- Note [!] Additional note (4)
--------------------------------------------------------------------------------
Note (1): Parallax type as follows:
First = First trigonometric parallaxe;
Revised = Revised parallaxe.
Note (2): Where 4-6 months of observations count as one season, with
observations typically occurring on 2-3 nights.
Note (3): Flag as follows:
c = Indicates a continuous set of observations where multiple nights of
data were taken in each season.
s = Indicates scattered observations when one or more seasons have only a
single night of observations.
Generally, "c" observations are better.
Note (4): Note as follows:
! = Additional details about the system is provided in Section 4.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Source identifier
17- 32 A16 --- OName Other common identifier
34- 38 F5.2 mag Vmag [11.49/20.25]? CTIO Johnson V band magnitude
39 A1 --- f_Vmag [J] Flag on Vmag (1)
41- 45 F5.2 mag Rmag [10.49/19.3] CTIO Cousins R band magnitude
46 A1 --- f_Rmag [J] Flag on Rmag (1)
48- 52 F5.2 mag Imag [9.31/18.34] CTIO Cousins I band magnitude
53 A1 --- f_Imag [J] Flag on Imag (1)
55 I1 --- Num [1/4] Number of VRI observation(s)
57 A1 --- Filter [VRI] Filter used to obtain parallax
59- 64 F6.4 mag sigma [0.0061/0.1282]? Variability in Filter
66- 70 F5.2 mag Jmag [8.13/14.44]? 2MASS J band magnitude
72- 75 F4.2 mag e_Jmag [0.02/0.04]? Uncertainty in Jmag
76 A1 --- f_Jmag [J] Flag on Jmag (1)
78- 82 F5.2 mag Hmag [7.61/14.12]? 2MASS H band magnitude
84- 87 F4.2 mag e_Hmag [0.02/0.06]? Uncertainty in Hmag
88 A1 --- f_Hmag [J] Flag on Hmag (1)
90- 94 F5.2 mag Ksmag [7.36/13.97]? 2MASS Ks band magnitude
96- 99 F4.2 mag e_Ksmag [0.02/0.06]? Uncertainty in Ksmag
100 A1 --- f_Ksmag [J] Flag on Ksmag (1)
102-109 A8 --- SpType Spectral type (2)
111-112 I2 --- Ref [1/16] Reference code (3)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
J = A combined photometry.
Note (2): Stars without spectral types are noted with luminosity class only,
based on their locations on the H-R diagram or independent
metallicity measurements.
Note (3): Reference code as follows:
1 = Bidelman (1985, Cat. III/119);
2 = Dahn et al. (2008ApJ...686..548D 2008ApJ...686..548D);
3 = Gizis & Reid (1997, J/PASP/109/849);
4 = Gizis et al. (2000AJ....120.1085G 2000AJ....120.1085G);
5 = Gizis et al. (2011ApJ...736L..34G 2011ApJ...736L..34G);
6 = Hawley et al. (1996, Cat. III/198);
7 = Henry et al. (2002AJ....123.2002H 2002AJ....123.2002H);
8 = Jao et al. (2008AJ....136..840J 2008AJ....136..840J);
9 = Jao et al. (2011AJ....141..117J 2011AJ....141..117J);
10 = Reid (2003, J/AJ/126/2449);
11 = Reid & Gizis (2005, J/PASP/117/676);
12 = Reid et al. (2007, J/AJ/133/2825);
13 = Rodgers & Eggen (1974PASP...86..742R 1974PASP...86..742R);
14 = Scholz et al. (2004A&A...428L..25S 2004A&A...428L..25S);
15 = Walker (1983SAAOC...7..106W 1983SAAOC...7..106W);
16 = This work.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Group [ABCD] Subdwarf group (1)
3- 4 I2 h RAh Hour of Right Ascension (J2000) (2)
6- 7 I2 min RAm Minute of Right Ascension (J2000) (2)
9- 13 F5.2 s RAs Second of Right Ascension (J2000) (2)
15 A1 --- DE- Sign of the Declination (J2000) (2)
16- 17 I2 deg DEd Degree of Declination (J2000) (2)
19- 20 I2 arcmin DEm Arcminute of Declination (J2000) (2)
22- 26 F5.2 arcsec DEs Arcsecond of Declination (J2000) (2)
28- 44 A17 --- Name Source identifier
46- 55 A10 --- OName Alternative source identifier
57- 61 F5.2 mag gmag [11.2/19.05]? g band magnitude
63- 67 F5.2 mag rmag [10.6/17.65]? r band magnitude
69- 73 F5.2 mag Vmag [7.61/18.24]? Johnson V band magnitude
75- 79 F5.2 mag V-Ks [1.7/18.24]? V-Ks color index
81- 85 F5.2 --- KsMag [3.54/10.08]? Absolute Ks band magnitude
87- 92 A6 --- SpType Spectral type
94- 95 I2 --- Ref [1/11]? Reference (3)
97-106 A10 --- Com Comment
--------------------------------------------------------------------------------
Note (1): Group as follows:
A = Previously identified as subdwarf;
B = New subdwarf candidate;
C = Previously identified as main sequence dwarf;
D = Binary, presumed main sequence dwarf.
Note (2): First, we submitted MEarth stars' equinox and epoch J2000 coordinates
to the PanSTARRS site (http://archive.stsci.edu/panstarrs/search.php) and set
the search radius to 0.5'. We calculated the mean epoch from all entries found
in this search. We then slid the MEarth stars' coordinates from J2000 to that
mean epoch using the MEarth proper motions. The second search was done by
querying these new coordinates with a reduced search radius of 0.1', and
"PSFMag" values were extracted.
Note (3): Reference as follows:
1 = Gizis & Reid (1997, J/PASP/109/849);
2 = Hawley et al. (1996i, Cat. III/198);
3 = Cruz & Reid (2002, J/AJ/123/2828);
4 = Reid & Gizis (2005, PASP 117 676);
5 = Reid et al. (2004, J/AJ/128/463);
6 = Scholz et al. (2005, J/A+A/442/211);
7 = Lepine et al. (2003, J/AJ/125/1598);
8 = Cruz & Reid (2002, J/AJ/123/2828);
9 = Radigan et al. (2008ApJ...689..471R 2008ApJ...689..471R);
10 = White et al. (2007, J/AJ/133/2524);
11 = Alonso-Floriano et al. (2015, J/A+A/577/A128).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
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(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 25-Jul-2018