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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)
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