the effects of birth environment on planetary...

The effects of birth environment

on planetary systems

Melvyn B. DaviesDepartment of Astronomy and Theoretical Physics

Lund Observatory

www.astro.lu.se

Five things to remember about

exoplanetary systems

Melvyn B. DaviesDepartment of Astronomy and Theoretical Physics

Lund Observatory

www.astro.lu.se

1) The Solar System

2) Lovis et al. (2010) list of multiple systems

3) Kepler systems

Lissauer et al. 2011; Tremaine & Dong 2012; Johansen et al. 2012; Fang & Margot 2012

There are many flat and/or low eccentricity planetary systems

Making everything from 3p systems

0 5 10 15 20 25 301t3p/3t3p

0

2

4

6

8

10

2t3p

/3t3

p

2.0 3.0

4.0 5.0

6.0 7.0

8.0 9.0

0.0

10.0

Kepler

Increasinginclinationspread

Kepler seesmore 1t than come from 3p

(Johansen, Davies, Church & Holmelin 2012)

1) The Solar System

2) Lovis et al. (2010) list of multiple systems

3) Kepler systems

Lissauer et al. 2011; Tremaine & Dong 2012; Johansen et al. 2012; Fang & Margot 2012

There are many flat and/or low eccentricity planetary systems

But some exoplanets are also observed on eccentric orbits... are they de-stabilised by encounters?

Encounters within birth environments happen interestingly often

Timescale for a given star to undergo an encounter is

τenc ' 3.3⇥107yr✓100 pc�3

n

◆✓V∞

1 km/s

◆✓103AURmin

◆✓M�Mt

◆

Beware of the average: lumpiness can make a difference.

(e.g. Malmberg et al. 2007; Davies et al. 2014)

Close fly-by Binary earlier Binary today

WS-10 ~0.10 ~0.05 ~0.03CL-10 ~0.15 ~0.20 ~0.15WS-all ~0.20 ~0.20 ~0.03CL-all ~0.20 ~0.50 ~0.10

In other words: fly-bys and exchanges into binary systems can happen interestingly often.

Fraction of solar-like stars suffering encounters

(Church, Davies & Bonnerot, in prep.)

Encounters can mess up planetary systems

The four gas giants 108 years after fly-by (rMin < 100 AU)

(Malmberg, Davies & Heggie 2011; see also Scharf & Menou 2009; Veras, Crepp & Ford 2009)

The four gas giants in a binary

(Malmberg, Davies & Chambers 2007;Malmberg & Davies 2009)

In Kepler zone many planetary systems are multiple but most hot Jupiters are single

(Mustill, Davies & Johansen 2015)

3p+J=np or J3p+np=p?

Injecting planets in from further out can mess up inner system

(Mustill, Davies & Johansen 2015;Mustill, Davies & Johansen in prep.)

1. Planetary systems are often flat

2. Encounters happen in birth environments

3. Encounters mess up planetary systems

4. Kepler sees multiple p, single J, or single p

5. 3p+J or 3p+np may make what we see

Summary