1. Young Associations in the CoRot Fields
Carlos Alberto O.Torres
LNA/MCT

2. SACY Search for Associations Containing Young stars
20/06/2018
Carlos A. O. Torres & Germano R. Quast (LNA / MCT)
Ramiro de la Reza & Licio da Silva (ON / MCT)
Claudio H. F. Melo & Michael Sterzik (ESO)

3. Background 80’s - Isolated T Tauri stars?
89 - New T Tauri stars found around TW Hya
90’s - PDS (IRAS)
Horologium Association (ROSAT) & Tucana Association 
Both nearby (~50 pc), adjacent, with similar
kinematics and ages
 a unique and large association?

4. Sample definition SACY (and CoRot)
20/06/2018
Sample definition SACY (and CoRot)
ROSAT All-Sky Bright (and faint) Source Catalogue
Proper motions from TYCHO-2 (and UCAC2)
(B-V)  0.6 (later than G0) (or any, brighter than 14)
Excluding known RS CVn, W UMa, giants, etc (SIMBAD)

5. Goals Li abundance Metallicity Radial and Rotational Velocities
Duplicity
Evolutionary stage

6. Statistics Southern ROSAT Sources SACY [Hip + TYC & (B-V)0.6]
Observed objects (not sources)
Data from literature
9574
2071
1489
118

7. 20/06/2018

9. RESULTS Giants  275 Dwarfs (IV & V)  1332  SB  10%  16%  38%
Young stars (*)  518
Pleiades age  296
Old stars  518
(*) Includes dwarf stars later than M0

10. UVW from 6D clustering analysis UVW taken from literature
from stars with
parallaxes
UVW from 6D clustering analysis
UVW
taken from
literature
Age from Li
strength or
Isochrone fitting
1st step – look for concentration in the UVW space
Concentration
detected around U0V0W0 Group/Association?

11. Loop over all young objects in the catalogue
Minimize:
Yes
Out of ad-hoc XYZ
constraints to the
member
list?
2nd step - Loop over catalogue until convergence is reached
Star
rejected No
New ad-hoc XYZ constraints to the member list?
New F?
Add star to
Member list
Compute new U0V0W0 using new member list

12. Tuc-HorA

13. Tuc-HorA

14. Tuc-HorA

15. Tuc-HorA

16. Tuc-HorA

22. Insights
The distribution of young stars in the solar neighborhood is patchy, forming huge kinematical associations.
We recognize at least 14 young associations in the SACY database (there are five more possible associations to verify) .

23. How is the situation in the CoRot fields at this moment ?

24. CI R J SpT EXODAT comments Target HD43587
Objects Observed in the Anti-Center Direction
CI R J SpT EXODAT comments
Target HD43587
K0IIIe G0III Li=0.13 SB1 RS CVn?
G2?
M4Ve
G4IV ? Li=0.19
K2IV K0III Li=0.24
Target HD HD49454
K1:III: G5III D?
A5: A5V
K:IIIe+Ve K0III RSCVn
Target HD52265 A?
G8IV Li=0.20
G2V Li=0.18 F?
G3V Li=0.18

25. Objects Observed in the Galactic-Center Direction
Objects Observed in the Galactic-Center Direction
CI R J SpT EXODAT comments
Target HD170580
K2III/IVe ? RSCVn
M3III M6III IRAS + Radio
K7Ve G5III Li?
K3V ? Li=0.09?
K3V K1III Li=0.21 D5"
G5V A5III Li=0.15?
KOIII K5III
A0III A5IV
K2III ?
K4V(e) K0III SB2 A~B
Target HD177552
? K2III ?
G5I G8III
K1V K2V
M4III IRAS Li=0.03
Targets HD HD180642
K2IV(e) ? Li=0.02?
G3V ? SB2?
G7IV G2V Li=0.04?
K2III K2III Li=0.08 RSCVn?
K6IVe ? SB2 B/A~0.8

26. The CoRot Anti-center Association
D = ± 40 pc
U = ± 0.9 km/s
V = ± 1.4 km/s
W = ± 1.4 km/s
X = ± 37 pc
Y = ± 30 pc
Z = ± 5 pc
N = 5 (+2?)
Age ~ 50 Myr

29. We have indications that we can find Young Associations in the CoRot fields, and obtain stellar ages.
In Ripepi’s Do25 sample there are two other possible associations. More observations are need.
Spectral Types in EXODAT should be taken with caution
There are other interesting active objects in our sample (RS CVn, etc).