Astrometry: A Third Method?
Alan Boss, Alycia Weinberger, and Ian Thompson (from Carnegie Observatories) have been running the Carnegie Astrometric Planet Search (CAPS) program, which searches for extrasolar planets by the astrometric method. Similar to radial velocity, astronomers using the astrometrymethod detect a planet's presence indirectly through the wobble of the host.
Can gas giant exoplanets orbit at large distances from their stars?
Observations have shown that gas giant exoplanets can orbit at large distances from their stars
Where the competing mechanism of slow core accretion has trouble forming gas giant exoplanets.
Boss has shown that disk instability has no such problem
As it is a rapid means for forming protoplanets during the short life of planet-forming disks.
CORE Accretion vs. Disk Instability
There are two main ways we think planets form in these protoplanetary disks. The core accretion mechanism holds that a gas-giant first forms a large, mostly rocky, core with enough mass and hence gravity to pull in gas from the surrounding disk to form a thick atmosphere, eventually becoming huge gas worlds. The competing idea is the disk instabili.
Do Metal-Rich Stars Make Metal-Rich Planets?
The relationship between the compositions of gas giants and their host stars is key to understanding planet formation. We know that close-in (hot) giant planets are more often found around stars with high iron abundances/metal abundances in general. This led to the obvious question: Do metal-rich stars also make metal-rich planets? Teske and her co.
How do astronomers detect a planet's presence?
Similar to radial velocity
Astronomers using the astrometry method detect a planet's presence indirectly through the wobble of the host star around the center of mass of the system.
However
Instead of measuring the changes in velocity
Astrometry relies on precise measurements of the star’s position.
How do scientists find exoplanets?
There are two main ways scientists at Carnegie find exoplanets.
In the transit method
A planet passes between a star and our telescope so astronomers measure a dip in the light.
How Do Sub-Neptunes and Super-Earths form?
These planets are the most common in the Galaxy, and yet we don't have one in our Solar System. To understand why we first need to know what these planets are made of so we can attempt to pin down how they are formed. To do this, astronomer Johanna Teske takes mass and radius measurements of planets to estimate their compositions. She is also start.
Modelling System Development
It takes up to hundreds of millions of years for a planetary system to form. Constructing mathematical models of Solar System creation is another way scientists fill in the gaps and test out new theories. Theoretical astrophysicist Alan Bosscreates mathematical models of disks using the information we know from observations like those done by Weinb.
Observing Disks and Planet Development
Observational astrophysicist Alycia Weinbergerdirectly observes protoplanetary disks in order to understand how planets form. Weinberger uses a variety of observational techniques and facilities to tease apart disk development. For example, with the Hubble Space Telescope,Weinberger images the smallest dust grains in disks at different wavelengths .
The Search For Exoplanets
Since the mid-1980’s Butler’s focus has been producing and improving the precision of Doppler velocity measurements of nearby stars. In the mid-1980s Doppler velocity precision was stalled at 300 m/s. (In contrast, Jupiter induces a 10 m/s Doppler velocity variation on the Sun.) Starting in chemistry labs at San Francisco State University, Butler d.
Transit Method vs. Doppler Velocity
There are two main ways scientists at Carnegie find exoplanets. In the transit method, a planet passes between a star and our telescope so astronomers measure a dip in the light. In theDoppler velocitymethod—also known as the radial velocity method—the push and pull between a star and its orbiting planet causes the star to wobble slightly on its ax.
