Scientists Find Possible Birth of Tiniest Known Solar System ? Jeng-Lwen, Chiu Institute of Physics, NTHU 2005 / 12 / 15

Cha RA : 11h 09m 13.63s DEC : -77°34’44”.6 Distance: pc Position: Chamaeleon I (star-forming region) Photometry : m 775 = 23.19, m 850 = 21.59, J = 17.45, H = 16.34, K s = 15.61, [3.6] = 14.70, [4.5] = 14.38, [5.8] = 14.11, [8.0] = (error: 0.02 for former 7, 0.04 for latter two) Extinction: A J = 0.3±3 Bolometric luminosity: L bol = -3.22±0.12 Age: T ~ 0.5 – 10 Myr (median : 2 Myr)

Hubble Space Telescope Spitzer Space Telescope 8m Gemini South Telescope 4m Blanco CTIO

Spectrum of Cha Broad, deep absorption in H2O  cool, Late type (>M9.5) Weak K I and Na I absorption lines Triangular shape of the continuum (1.5~1.8 μm)  Low surface gravity & young age (pre- main-sequence) OTS 44 : young brown dwarfLHS 2065 : old cool dwarf (M9 V)

Filled circles: Luminosities of the young brown dwarfs KPNO 4, OTS 44, and Cha Dashed lines: the luminosities as a function of age predicted by the evolutionary models.  Mass = M J Luminosity of Cha

The fluxes are photospheric in optical and near-IR bands. Significant excess emission is present at wavelengths > 5 μm M*=8 M J ; R*=1.8 R J n(a) ~ a -3.5 Vertical wall : Rwall ~2.1R* (1300K) ; H wall ~ 0.17 R* dM ~< Ms/yr Spectral energy distribution

"Our goal is to determine the smallest 'sun' with evidence for planet formation," said Luhman. "Here we have a sun that is so small it is the size of a planet. The question then becomes, what do we call any little bodies that might be born from this disk: planets or moons?“ If this proto-planetary disk does form into planets, the whole system would be a miniaturized version of our solar system -- with the central "sun", the planets, and their orbits all roughly 100 times smaller.

There are two camps when it comes to defining planets versus brown dwarfs. Some go by size, and others go by how the object formed. For instance, this new object would be called a planet based on its size, but a brown dwarf based on how it formed. If one were to call the object a planet, then Spitzer may have discovered its first "moon-forming" disk. 0.08~0.8 M sun (H fusion) 0.013~0.08 M sun (D fusion) < M sun (0.001)

No matter what the final label may be, one thing is clear: “The universe produces some strange solar systems very different from our own. “ (said team member Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.)

~ Thank you ~ Reference: News “DISCOVERY OF A PLANETARY-MASS BROWN DWARF WITH A CIRCUMSTELLAR DISK” (Luhman, K. L., et al. 2005, ApJ, 635, L93) Pictures (Spitzer) (HST) (CERRO TOLOLO INTER-AMERICAN OBSERVATORY) (Gemini South) (Brown dwarf)

Brown dwarf M ~ – 0.08 M sun T ~ K (L type) M < M sun (0.001 M sun ) T ~ 1000 – 1600 K (124K) Planet