J/ApJ/868/32 A large moving group within the LCC association (Goldman+, 2018)
A large moving group within the Lower Centaurus Crux association.
Goldman B., Roser S., Schilbach E., Moor A.C., Henning T.
<Astrophys. J., 868, 32-32 (2018)>
=2018ApJ...868...32G 2018ApJ...868...32G (SIMBAD/NED BibCode)
ADC_Keywords: YSOs; Stars, brown dwarf; Associations, stellar; Positional data;
Stars, masses; Stars, ages; Effective temperatures;
Cross identifications; Photometry; Optical
Keywords: brown dwarfs; stars: luminosity function, mass function;
open clusters and associations: individual: Lower Centaurus Crux;
protoplanetary disks; stars: formation
Abstract:
Scorpius-Centaurus is the nearest OB association, and its hundreds of
members are divided into subgroups, including the Lower Centaurus Crux
(LCC). Here we study the dynamics of the LCC area. We report the
revelation of a large moving group containing more than 1800
intermediate- and low-mass young stellar objects and brown dwarfs that
escaped identification until Gaia DR2 allowed a kinematic and
photometric selection to be performed. We investigate the stellar and
substellar content of this moving group using the Gaia DR2 astrometric
and photometric measurements. The median distance of the members is
114.5pc, and 80% lie between 102 and 135pc from the Sun. Our new
members cover a mass range of 0.02-5M☉ and add up to a total
mass of about 700M☉. The present-day mass function follows a
log-normal law with mc=0.22M☉ and σ=0.64. We find more
than 200 brown dwarfs in our sample. The star formation rate had its
maximum of 8x10-5M☉/yr about 9Myr ago. We grouped the new
members into four denser subgroups, which have increasing age from 7
to 10Myr, surrounded by "free-floating" young stars with mixed ages.
Our isochronal ages, now based on accurate parallaxes, are compatible
with several earlier studies of the region. The whole complex is
presently expanding, and the expansion started between 8 and 10Myr
ago. Two hundred members show infrared excess compatible with
circumstellar disks from full to debris disks. This discovery provides
a large sample of nearby young stellar and substellar objects for disk
and exoplanet studies.
Description:
All parameters based on or derived from Gaia DR2 (I/345).
Objects:
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RA (ICRS) DE Designation(s)
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12 19 -57.1 Lower Centaurus Crux = NAME Lower Centaurus Crux
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
members.dat 956 1844 Lower Centaurus Crux (LCC) member parameters
(see Table 4)
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
III/254 : 2nd Cat. of RVs with Astrometric Data (Kharchenko+, 2007)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/AJ/153/257 : Comoving stars in Gaia DR1 (Oh+, 2017)
J/A+A/595/A22 : 9 new open clusters within 500pc from the Sun (Roser+, 2016)
J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)
J/ApJS/225/15 : IR excess stars from Tycho-2 and AllWISE (Cotten+, 2016)
J/MNRAS/458/3479 : SVM selection of WISE YSO Candidates (Marton+, 2016)
J/MNRAS/437/391 : IR excess in Sun-like stars with WISE (Cruz-Saenz+, 2014)
J/A+A/558/A53 : MW global survey of star clusters. II. (Kharchenko+, 2013)
J/MNRAS/431/3222 : UKIDSS GCS Upper Sco members (Lodieu, 2013)
J/ApJ/758/31 : IR photometry for members of Upper Sco (Luhman+, 2012)
J/ApJ/756/133 : ScoCen debris disks around B- and A-type stars (Chen+, 2012)
J/ApJ/754/30 : VISTA IR phot. of σ Ori cluster (Pena Ramirez+, 2012)
J/AJ/144/8 : ∼100 G/K/M-type Sco-Cen complex members sp. (Song+, 2012)
J/ApJ/746/154 : Kinematic parallaxes for Sco-Cen members (Pecaut+, 2012)
J/ApJ/743/64 : Deep IR photometry of σ Ori cluster (Bejar+, 2011)
J/MNRAS/416/3108 : Membership of Sco OB2 moving group (Rizzuto+, 2011)
J/ApJ/738/122 : ScoCen debris disks Around F- and G-type stars (Chen+, 2011)
J/A+A/531/A92 : Deep all-sky census of the Hyades (Roeser+, 2011)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/AN/328/889 : Mean Radial Velocities of open clusters (Kharchenko+, 2007)
J/AJ/133/889 : Faint companions of Hipparcos stars (Lepine+, 2007)
J/MNRAS/363/1111 : Tycho-2 stars with IR excess (Clarke+, 2005)
J/AJ/129/1049 : Mm and sub-mm obs. of solar-type stars (Carpenter+, 2005)
J/A+A/404/913 : Kinematics & HRD of Southern Young Stars (Sartori+ 2003)
J/AJ/124/1670 : Post-T Tauri Stars in Sco-Cen Association (Mamajek+, 2002)
J/MNRAS/313/43 : OB assoc. members in ACT+TRC Catalogs (Hoogerwerf, 2000)
J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)
J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
J/ApJ/497/330 : Candidate main-sequence stars (Mannings+, 1998)
J/A+AS/106/275 : Theoretical isochrones (Bertelli+ 1994)
J/A+A/216/44 : Walraven photometry in Sco-Cen association (De Geus+, 1989)
Byte-by-byte Description of file: members.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 28 A28 --- DR2Name Gaia DR2 designation (designation)
30- 31 A2 --- Group Group (A, A0, B, C or Z) (1)
33- 47 F15.11 deg RAdeg [164.4/228.1] Gaia DR2 barycentric right
ascension (ICRS) at Ep=2015.5 (ra)
49- 63 F15.11 deg DEdeg [-77/-40.8] Gaia DR2 barycentric
declination (ICRS) at Ep=2015.5 (dec)
65- 71 F7.4 mas e_RAdeg [0.01/0.4] Standard error of RAdeg
(e_RA*cosDE) (ra_error)
73- 79 F7.4 mas e_DEdeg [0.01/0.5] Standard error of DEdeg
(dec_error)
81- 89 F9.3 mas/yr pmRA [-43/-21] Proper motion in RA
direction (pmRA*cosDE) (pmra)
91- 99 F9.3 mas/yr pmDE [-31.2/5] Proper motion in declination
direction (pmdec)
101- 105 F5.3 mas/yr e_pmRA [0.02/0.7] Standard error of pmRA
direction (pmra_error)
107- 111 F5.3 mas/yr e_pmDE [0.02/0.8] Standard error of pmDE
direction (pmdec_error)
113- 122 F10.4 mas Plx [7/12] Absolute stellar parallax
(parallax)
124- 129 F6.4 mas e_Plx [0.02/0.6] Standard error of parallax
(parallax_error)
131- 140 F10.4 --- RPlx [14.5/418.5] Parallax divided by
its error (parallaxovererror)
142- 148 F7.4 --- RADEcor [-0.7/1] Correlation between RA
and DEC (radeccorr)
150- 156 F7.4 --- RAPlxcor [-1/0.5] Correlation between RA
and parallax (raparallaxcorr)
158- 164 F7.4 --- RApmRAcor [-0.9/0.5] Correlation between RA
and pmRA (rapmracorr)
166- 172 F7.4 --- RApmDEcor [-0.7/0.7] Correlation between RA
and pmDE (rapmdeccorr)
174- 180 F7.4 --- DEPlxcor [-1/0.6] Correlation between DEC and
parallax (decparallaxcorr)
182- 188 F7.4 --- DEpmRAcor [-0.8/0.8] Correlation between DEC and
pmRA (decpmracorr)
190- 196 F7.4 --- DEpmDEcor [-1/0.9] Correlation between DEC and
pmDE (decpmdeccorr)
198- 204 F7.4 --- PlxpmRAcor [-0.7/0.8] Correlation between parallax
and pmRA (parallaxpmracorr)
206- 212 F7.4 --- PlxpmDEcor [-0.9/0.8] Correlation between parallax
and pmDE (parallaxpmdeccorr)
214- 220 F7.4 --- pmRApmDEcor [-0.8/0.9] Correlation between pmRA and
pmDE (pmrapmdeccorr)
222- 224 I3 --- NAL [69/945] Total number of AL observations
(= CCD transits) (astrometricnobs_al)
226- 228 I3 --- NAC [0/919] Total number of observations AC
(astrometricnobs_ac)
230- 232 I3 --- NgAL [69/940] Number of good observations AL
(astrometricngoodobsal)
234- 235 I2 --- NbAL [0/74] Number of bad observations AL
(astrometricnbadobsal)
237- 245 F9.4 --- gofAL [-1/221] Goodness of fit statistic of
model wrt along-scan observations
(astrometricgofal)
247- 257 F11.2 --- chi2AL [85/93841] AL chi2 value
(astrometricchi2al)
259- 264 F6.3 mas epsi [0/2] Excess noise of the source
(astrometricexcessnoise)
266- 273 F8.3 --- sepsi [0/1759] Significance of excess noise
(astrometricexcessnoise_sig)
275- 276 I2 --- Solved [31] Which parameters have been solved
for? (31=all five astrometric parameters
were estimated)
(astrometricparamssolved)
278 I1 --- APF [0] Primary or secondary
(false=secondary source)
(astrometricprimaryflag)
280- 287 F8.4 mas-2 WAL [0.2/516] Mean astrometric weight of the
source (astrometricweightal)
289- 295 F7.4 um-1 pscol [0.9/2.2] Astrometrically determined
pseudocolour of the source
(astrometricpseudocolour)
297- 302 F6.4 um-1 e_pscol [0.003/0.08] Standard error of the
pseudocolour of the source
(astrometricpseudocolour_error)
304- 309 F6.3 --- fvarpi [-0.4/0.4] Mean Parallax factor AL
(meanvarpifactor_al)
311- 313 I3 --- MatchObsA [8/108] Matched FOV transits
used in the AGIS solution
(astrometricmatchedobservations)
315- 316 I2 --- Nper [7/20] Number of visibility
periods used in Astrometric solution
(visibilityperiodsused)
318- 325 F8.6 --- amax [0.03/0.9] The longest semi-major axis
of the 5-d error ellipsoid
(astrometricsigma5dmax)
327 I1 --- type [0] The type of the source mainly used
for frame rotation (0=ordinary source)
(framerotatorobject_type)
329- 331 I3 --- MatchObs [10/110] The total number of FOV transits
matched to this source
(matched_observations)
333 I1 --- Dup [0] Source with duplicate sources
(false) (duplicated_source)
335- 337 I3 --- o_Gmag [81/946] Number of observations
contributing to G photometry
(photgn_obs)
339- 349 E11.5 e-/s FG [638/5.5e+08] G-band mean flux
(photgmean_flux)
351- 361 E11.5 e-/s e_FG [0.9/2.1e+06] FG error
(photgmeanfluxerror)
363- 371 F9.3 --- RFG [31/5654] G-band mean flux divided by
its error (photgmeanfluxover_error)
373- 381 F9.6 --- Gmag [3.8/18.7] G-band mean magnitude (Vega)
(photgmean_mag)
383- 385 I3 --- o_BPmag [2/103] Number of observations
contributing to BP photometry
(photbpn_obs)
387- 397 E11.5 e-/s FBP [38/4.3e+08] Mean flux in the integrated
BP band (photbpmean_flux)
399- 409 E11.5 e-/s e_FBP [3.9/1.2e+06] Error on FBP
(photbpmeanfluxerror)
411- 419 F9.3 --- RFBP [4/2465] Integrated BP mean flux
divided by its error
(photbpmeanfluxover_error)
421- 429 F9.6 --- BPmag [3.7/21.4] Integrated BP mean magnitude
(Vega) (photbpmean_mag)
431- 433 I3 --- o_RPmag [2/103] Number of observations
contributing to RP photometry
(photrpn_obs)
435- 445 E11.5 e-/s FRP [1103/2e+08] Mean flux in the integrated
RP band (photrpmean_flux)
447- 457 E11.5 e-/s e_FRP [5/577480] Error on FRP
(photrpmeanfluxerror)
459- 467 F9.3 --- RFRP [5/2173] Integrated RP mean flux
divided by its error
(photrpmeanfluxover_error)
469- 477 F9.6 --- RPmag [4/17.2] Integrated RP mean magnitude
(Vega) (photrpmean_mag)
479- 483 F5.3 --- E(BR/RP) [1.1/1.8] BP/RP excess factor
(photbprpexcessfactor)
485 I1 --- Mode [0/1] Photometry processing mode
(photprocmode)
487- 492 F6.2 km/s RV [-29/34.1]? Spectroscopic radial
velocity in the solar barycentric
reference frame (radial_velocity)
494- 498 F5.2 km/s e_RV [0.2/19.4]? Radial velocity error
(radialvelocityerror)
500- 501 I2 --- o_RV [0/37] Number of transits used to
compute radial velocity
(rvnbtransits)
503- 515 A13 --- Var Photometric variability flag
("VARIABLE" = 36 occurrences)
(photvariableflag)
517- 530 F14.10 deg GLON [285.2/319] Galactic longitude (l)
532- 545 F14.10 deg GLAT [-15.3/21.7] Galactic latitude (b)
547- 560 F14.10 deg ELON Ecliptic longitude (ecl_lon)
562- 575 F14.10 deg ELAT Ecliptic latitude (ecl_lat)
577- 582 I6 --- fPriam [100001/102002]? Flags for the
Apsis-Priam results (priam_flags)
584- 590 F7.2 K TeffA [3286/9705]? Stellar effective
temperature (estimate from Apsis-Priam)
(teff_val)
592- 598 F7.2 K b_TeffA [3115/9534]? Uncertainty (lower) on
TeffA (16th percentile)
(teffpercentilelower)
600- 606 F7.2 K B_TeffA [3343/9947]? Uncertainty (upper) on
TeffA (84th percentile)
(teffpercentileupper)
608- 613 F6.4 mag AG [0.02/3]? Estimate of extinction in
the G band from Apsis-Priam (agval)
615- 620 F6.4 mag b_AG [0/2.6]? Uncertainty (lower) on AG
estimate from Apsis-Priam
(16th percentile) (agpercentile_lower)
622- 627 F6.4 mag B_AG [0.06/3.2]? Uncertainty (upper) on AG
estimate from Apsis-Priam (84th
percentile) (agpercentile_upper)
629- 634 F6.4 mag E(BP-RP) [0.01/1.5]? Estimate of redenning
E(BP-RP) from Apsis-Priam
(ebpminrpval)
636- 641 F6.4 mag b_E(BP-RP) [0/1.3]?=- Uncertainty (lower) on
E(BP-RP) estimate from
Apsis-Priam (16th percentile)
(ebpminrppercentile_lower)
643- 648 F6.4 mag B_E(BP-RP) [0.03/1.7]?=- Uncertainty (upper) on
E(BP-RP) estimate from
Apsis-Priam (84th percentile)
(ebpminrppercentile_upper)
650- 655 I6 --- fFLAME [200111]?=- Flags for the Apsis-FLAME
results (flame_flags)
657- 660 F4.2 Rsun Rad [0.5/3]? Estimate of radius from
Apsis-FLAME (radius_val)
662- 665 F4.2 Rsun b_Rad [0.3/3]? Uncertainty (lower) on
radius estimate from Apsis-FLAME
(16th percentile)
(radiuspercentilelower)
667- 670 F4.2 Rsun B_Rad [0.5/3.1]? Uncertainty (upper) on
radius estimate from Apsis-FLAME
(84th percentile)
(radiuspercentileupper)
672- 677 F6.3 Lsun Lum [0.03/26]? Esimate of luminosity
from Apsis-FLAME (lum_val)
679- 684 F6.3 Lsun b_Lum [0.03/25.8]? Uncertainty (lower) on
luminosity estimate from
Apsis-FLAME (16th percentile)
(lumpercentilelower)
686- 691 F6.3 Lsun B_Lum [0.03/26.3]? Uncertainty (upper) on
luminosity estimate from
Apsis-FLAME (84th percentile)
(lumpercentileupper)
693- 699 F7.4 km/s RVpred [5.5/16.7] Predicted radial velocity
(vr_pred)
701- 707 F7.4 km/s Vpar [18.3/21.5] Observed tangential velocity
toward the convergent point (vpar)
709- 715 E7.4 km/s Vperp [-2.4/2.1] Observed tangential velocity
perpendicular to the convergent
point direction (vperp)
717- 722 F6.4 km/s e_Vpar [0.05/1.3] Uncertainty on the observed
tangential velocity toward the
convergent point (e_vpar)
724- 729 F6.4 km/s e_Vperp [0.01/0.5] Uncertainty on the observed
tangential velocity perpendicular
to the convergent point direction
(e_vper)
731- 737 E7.4 --- Vppcor [-0.9/0.8] Correlation between the
observed tangential velocities toward
and perpendicular to the convergent
point direction (vparvperpcor)
739- 746 F8.4 pc Xgal [26/103] X galactic coordinate derived
from Gaia DR2 parameters (x_gal)
748- 756 F9.4 pc Ygal [-134.1/-64.6] Y galactic coordinate
derived from Gaia DR2 parameters
(y_gal)
758- 765 F8.4 pc Zgal [-30.7/51] Z galactic coordinate derived
from Gaia DR2 parameters (z_gal)
767- 771 F5.3 Gyr AgeC [0.001/0.1]? Age according to the
CIFIST isochrones (age_CIFIST)
773- 778 F6.4 Msun MassC [0.02/1.4]? Mass according to the
CIFIST isochrones (Mass_CIFIST)
780- 786 F7.2 K TeffC [2632/6766]? Effective temperature
according to the CIFIST isochrones
(Teff_CIFIST)
788- 794 F7.4 [Lsun] logLumC [-3/0.6]? log_10 of bolometric luminosity
according to the CIFIST isochrones
(Lum_CIFIST)
796- 801 F6.4 [g/cm/s2] loggC [3.4/5]? log_10 of gravity according to
the CIFIST isochrones (logg_CIFIST)
803- 811 E9.3 yr AgeP [5e+06/1e+08] Age according to the
Parsec isochrones (Age_P)
813- 818 F6.4 Msun MassP [0.1/5.4] Initial mass according to
the Parsec isochrones (mass_P)
820- 825 F6.3 [Lsun] logLumP [-2.7/3.1] log_10 of bolometric
luminosity according to the Parsec
isochrones (logL_P)
827- 830 F4.2 [K] logTeffP [3.4/4.3] log_10 of effective temperature
according to the Parsec isochrones
(logTe_P)
832- 837 F6.4 [g/cm/s2] loggP [3.7/4.8] log_10 of gravity according to
the Parsec isochrones (logg_P)
839- 843 F5.3 --- RecovR [0.6/1] Fraction of recovered stars of
same G magnitude (recovery_rate)
845- 851 F7.5 Gyr Age [0.001/0.11] Best age (Age)
853- 858 F6.4 Msun Mass [0.02/5.4] Best mass (Mass)
860- 867 F8.2 K Teff [2632/16726] Best effective temperature
(Teff)
869- 874 F6.3 [Lsun] LogLum [-3/3.1] log_10 of best bolometric
luminosity (LogL)
876- 894 A19 --- WISEA ID of AllWISE detection
(JHHMMSS.ss+DDMMSS.s) (AllWISE_ID)
896- 902 F7.3 [g/cm/s2] logLSED [-3.8/590]? log_10 of bolometric
luminosity according to the
VOSA fit, used for the
circumstellar disk analysis (LogL_SED)
904- 908 I5 K TeffSED [1200/18000]? Effective temperature
according to the VOSA fit,
used for the circumstellar
disk analysis (Teff_SED)
910- 929 A20 --- DkType Circumstellar disk classification
(disk_type)
931- 953 A23 --- SName Primary SIMBAD name (Simbad_name)
955- 956 I2 --- Ref ? Reference for circumstellar disk
(Ref) (2)
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Note (1): The Crux Moving Group (CMG) is divided into four subgroups (CMG A0,
CMG A, CMG B, and CMG C) listed in Table 1 and the CMG Intergroup
(CMG Z).
Excerpt of Table 1:
---------------------------------------------------------
Subgroup Nstars Dmedian Age Mass
(pc) (yr) (M☉)
---------------------------------------------------------
A0 49 103.0 7.0 13
A 149 106.5 7.2 50
B 317 109.5 9.3 98
C 487 118.0 10.0 249
---------------------------------------------------------
Note (2): The references for the last column giving the disk identification
codes are the following:
1 = Carpenter et al. (2005, J/AJ/129/1049);
2 = Chen et al. (2005ApJ...623..493C 2005ApJ...623..493C);
3 = Chen et al. (2011, J/ApJ/738/122);
4 = Chen et al. (2012, J/ApJ/756/133);
5 = Clarke et al. (2005, J/MNRAS/363/1111);
6 = Cotten & Song (2016, J/ApJS/225/15);
7 = Cruz-Saenz de Miera et al. (2014, J/MNRAS/437/391);
8 = Fujiwara et al. (2009ApJ...695L..88F 2009ApJ...695L..88F);
9 = Gregorio-Hetem et al. (1992AJ....103..549G 1992AJ....103..549G);
10 = Mannings & Barlow (1998, J/ApJ/497/330);
11 = Marton et al. (2016MNRAS.458.3478M 2016MNRAS.458.3478M);
12 = Melis et al. (2012Natur.487...74M 2012Natur.487...74M);
13 = Melis et al. (2013ApJ...778...12M 2013ApJ...778...12M);
14 = Oudmaijer et al. (1992A&AS...96..625O 1992A&AS...96..625O);
15 = Pecaut & Mamajek (2016, J/MNRAS/461/794);
16 = Rizzuto et al. (2012, J/MNRAS/416/3108);
17 = Schneider et al. (2012ApJ...757..163S 2012ApJ...757..163S);
18 = this work.
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Acknowledgements:
Bertrand Goldman, <goldman(at)lilo.org>
(End) Bertrand Goldmann [Unistra], Emmanuelle Perret [CDS] 13-Dec-2018