Scientists Find Possible Birth of Tiniest Known Solar System ?

Jeng-Lwen, ChiuInstitute of Physics, NTHU

2005 / 12 / 15

Cha 110913-773444

• RA : 11h 09m 13.63s• DEC : -77°34’44”.6• Distance: 160-170 pc• Position: Chamaeleon I (star-forming region)

• Photometry : m775 = 23.19, m850 = 21.59,

J = 17.45, H = 16.34, Ks = 15.61,

[3.6] = 14.70, [4.5] = 14.38, [5.8] = 14.11, [8.0] = 13.49 (error: 0.02 for former 7, 0.04 for latter two)

• Extinction: AJ = 0.3±3

• Bolometric luminosity: Lbol = -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 Telescope @ CTIO

Spectrum of Cha 1109-7734• Broad, deep absorp

tion in H2O cool, Late type (>M

9.5)

• Weak K I and Na I absorption lines

• Triangular shape of the continuum (1.5~1.8 μm)

Low surface gravity & young age (pre-m

ain-sequence)

OTS 44 : young brown dwarf LHS 2065 : old cool dwarf (M9 V)

• Filled circles: Luminosities of the young brown dwarfs KPNO 4, OTS 44, and Cha 1109-7734.

• Dashed lines: the luminosities as a function

of age predicted by the evolutionary models.

Mass = 8+-7

3 MJ

Luminosity of Cha 1109-7734

• The fluxes are photospheric in optical and near-IR bands.

• Significant excess emission is present at wavelengths > 5 μm

• M*=8 MJ ; R*=1.8 RJ

• n(a) ~ a -3.5

• Vertical wall : Rwall ~2.1R* (1300K) ; H wall ~ 0.17 R*

• dM ~< 10-12 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 Msun (H fusion)

0.013~0.08 Msun (D fusion)

< 0.013 Msun (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 CIRCUMSTEL

LAR DISK” (Luhman, K. L., et al. 2005, ApJ, 635, L93)• http://www.science.psu.edu/alert/Luhman11-2005.htm

Pictures• http://www.spitzer.caltech.edu/Media/mediaimages/hardware.shtml (Spitzer)

• http://hubble.nasa.gov/multimedia/hubble.php (HST)

• http://www.ctio.noao.edu/ (CERRO TOLOLO INTER-AMERICAN OBSERVATORY)

• http://www.gemini.edu/index.php?option=com_gallery (Gemini South)

• http://www.lcsd.gov.hk/CE/Museum/Space/FAQ/star/c_faq_star_42.htm (Brown dwarf)

Brown dwarf

• M ~ 0.013 – 0.08 Msun • T ~ 1300 - 2500 K (L type)

• M < 0.013 Msun (0.001 Msun)

• T ~ 1000 – 1600 K (124K)

Planet