Transcript Scientists Find Possible Birth of Tiniest Known Solar System ?

Scientists Find Possible Birth of
Tiniest Known Solar System ?
Jeng-Lwen, Chiu
Institute of Physics, NTHU
2005 / 12 / 15
Cha 110913-773444
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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)
4m Blanco Telescope @ CTIO
Spitzer Space Telescope
Hubble Space Telescope
8m Gemini South Telescope
Spectrum of Cha 1109-7734
• 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 (premain-sequence)
OTS 44 : young brown dwarf
LHS 2065 : old cool dwarf (M9 V)
Luminosity of Cha 1109-7734
• 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+-73 MJ
Spectral energy distribution
• 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
• "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.
0.08~0.8 Msun (H fusion)
0.013~0.08 Msun (D fusion)
< 0.013 Msun (0.001)
• 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.
• 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.)
Reference:
News
• “DISCOVERY OF A PLANETARY-MASS BROWN DWARF WITH A
CIRCUMSTELLAR 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)
~ Thank you ~
Brown dwarf
• M ~ 0.013 – 0.08 Msun
• T ~ 1300 - 2500 K (L type)
Planet
• M < 0.013 Msun (0.001 M )
• T ~ 1000 – 1600 K (124K)
sun