Planetary systems and their changing theories

table of contents

Other worlds discovered. II. Exoplanets

Planets around pulsars

Epochal discovery of PSR B1257+12 in 1992
Properties

System (planet)	m (M_J) sin i	a (AU)	e
PSR B1257+12 (A)	4.7 10^-5	0.19	~0
PSR B1257+12 (C)	0.009	0.47	0.026
PSR B1257+12 (B)	0.011	0.36	0.018
PSR B0329+54 (A)	0.0063	7.3	0.23

The fortunate near-resonant structure of the PSR B1257+12 system allowed confirmation of 2 planets in 1994
"Who ordered that?"

Candidate extrasolar systems around sun-like stars (1995-1997)

System (planet)	min. m (M_J)	a (AU)	e
51 Peg	0.47	0.05	0.0
tau Boö	3.8	0.045	0.0
upsilon And	0.61	0.057	0.15
55 Cnc	0.84	0.11	0.05
rho CrB	1.1	0.23	0.03
47 UMa	2.8	2.1	0.03
16 Cyg B	1.5	1.7	0.67
Gliese 876	1.68 (µ: 5.8)	0.2	0.36
70 Vir	6.6	0.43	0.39
HD 114762	9	0.3	0.33
other...	<5 ?	<1 ?	eccentric

Please check out the Extrasolar Planet Encyclopaedia for the newest data

Why are we surprised?

The theoretical expectations or the prior `common knowledge' (left) are compared with the 1995-1997 observations (right).

What we've ordered:	What we've got:
Planetary systems around 1/3(?) of main-seq. stars many planets spaced by a const. factor f=1.5-2.5 (perhaps obeying Titius-Bodes-law)	Dominant giant planets >4% of main-seq. stars single planets (so far) no Saturns in sight (f>>1) disobeying Bode's law
Giant planets not in all planet. sys. (<50%) not much heavier than Jupiter roughly Jupiter's radius Jovian-like composition & structure	Giant "planets" %=? some much more massive than Jupiter radius=?
Familiar orbits in equatorial plane of the star all in prograde motion slightly inclined nearly circular a>5 AU for giants, any distance for terrestrial planets stably configured	Unfamiliar orbits 'Hot' Jupiters - too close Normal Jupiters Eccentric super-Jupiters Pulsar planets - some eccentric

table of contents