Discovery of a wide planetary mass companion of a very young brown dwarf

1. Discovery of a wide planetary mass companion of a very young brown dwarf “Breaking News” Talk. ApJ Letter La Laguna 2008 Víctor J. S. Béjar Collaborators: M. R. Zapatero Osorio, A. Pérez-Garrido, C. Álvarez, E. L. Martín, R. Rebolo, I. Villó-Sánchez, A. Díaz-Sánchez

2. Outline • Short introduction to substellar objects • Discovery of UScoCTIO108B • Possible formation mechanisms • Relevant results of the letter

3. (Chabrier & Baraffe 2000) Brown dwarfs and planets • Substellar objects does not stably burn H (M<75 MJup ) • Brown Dwarfs M<65 MJup does not burn Li (the Li test) • Substellar objects M<13 MJupdoes not burn D(Brown dwarf/planet frontier)

4. Direct image of extrasolar planets >250 extrasolar planets discovered by indirect tecniques (radial velocity, transits,..) Secondary transit of an extrasolar planet behind its star with Spitzer (Deming et al. 2005; Charbonneau et al. 2005) 2M1207AB: Enana marrón y planeta en TWA (10 Ma, 70 pc) (Chauvin et al. 2004, 2005)

5. Discovery of USco CTIO 108B "Discovery of a wide companion near the deuterium-burning mass limit in the Upper Scorpius association" Béjar, V. J. S.; Zapatero Osorio, M. R.; Pérez-Garrido, A.; Álvarez, C.; Martín Guerrero, E. L.; Rebolo, R.; Villó-Pérez, I.; Díaz-Sánchez, A. 2008, ApJ Letter, 673, L185

6. The Upper Scorpius association • Distance ~ 145pc • Age ~ 5 Myr

7. Images of the UScoCTIO 108 companion 2MASS search for red objects (J-Ks>1) around 500 candidates members of USco Discovery image: J-band 2MASS Colour composite image: IJK’ (WHT,TNG) ρ~ 4.6” (670UA) θ = 177° Discovery image: I-band IAC80

8. Photometry of UScoCTIO 108 A & B • Common proper motion with Upper Scorpius association (-11,-25 mas/yr) • UScoCTIO108A:µαcosδ,µδ = (-8,-17 mas/yr) • UScoCTIO 108B:µαcosδ,µδ= (-6,-20 mas/yr), but large error bar • Both objects belong to the photometric sequence of the association

9. Spectroscopy of UScoCTIO 108 A & B • UScoCTIO 108 B: • SpType: M9.5-L3 • Low gravity features • Activity • Teff= 2150 ± 300 K • UScoCTIO 108 A: • SpType: M7 • Low gravity features • Li is totally preserved • Signatures of an accretion disks • Teff= 2700 ± 100 K

10. Physical parameters of UScoCTIO 108 AB Masses from theoretical models (Burrows et al. 1997; Baraffe et al. 2003) 60 ± 20 MJup 14+2-8 MJup Mbol=MIJK+BCIJK (SpT) UScoCTIO 108 A: LogL/Lsol = -1.95 ± 0.15 UScoCTIO 108 B: LogL/Lsol = -3.14 ± 0.20

11. Binarity of UScoCTIO 108AB • Probability ofchance alignment: <<1.3% • Projected separation: 670 UA (period 65500 yr) • Escape velocity: 0.4Km/s • Disruption Time (USco: 0.3 obj/pc3): ≥200 Myr (Solar neigh: 0.07obj/pc3): >10Gyr <5Myr ->density of birth <20obj/pc3 (Weinberg et al. 1987; Binney&Tremaine 1987) • Dissipation time of Upper Scorpius : ~10Myr There could be similar systems at Solar age • MJ=15,22 (J=17 a 1pc) • Teff=1000, 350 K • Sp Type = T6, Y? Close et al. 2007

12. Formation of UScoCTIO 108B • DISK • Core-Accretion: Similar to the current accepted Solar System models (Pollack et al. 2006).Problem: Only a few Jupiter masses is available at distances <50UA • Disk Fragmentation(Boss 2006).Problem: Fragments of 10 MJup con be formed, but at much shorter separations (<100-200UA) • Protostellar embryo ejection (Reipurth & Clarke 2001). Problem: Ejection need close encounters which disrupt the system • Collapse and Fragmentation of proto-(sub)stellar “cores”:Similar to other stellar binaries are formed(Bodenheimer 1998). Problem:Similar to form isolated planetary mass objects (IPMOs) If these systems formed in denser environment, they will become IPMOs

13. Relevant results • Direct image and spectroscopy of the least luminous and massive companion, after 2M1206b • Substellar companion at the widest projected separation (670UA) and lower gravitational bound energy • Key to understand the formation of isolated planetary mass objects • Detected in the IAC80!!!