Metropolitan Digital

The Conversation

  • Written by Natalie Hinkel, Planetary Astrophysicist, Senior Research Scientist at the Southwest Research Institute and Co-Investigator for the Nexus for Exoplanet System Science (NExSS), Arizona State University

Stars are born when huge clouds of dust and gas collapse[1] in on themselves and ignite. These clouds are made up of raw elements, like oxygen and titanium, and each cloud has a unique composition[2] that imprints on the star. And within the stellar afterbirth – from the material that didn’t find its way into the star – planets are formed.

Finding planets orbiting distant stars, or exoplanets, is difficult. There are tried and true methods that involve using large telescopes to detect these tiny objects. But I’ve developed a faster and more powerful strategy for planet hunting that is based on the chemistry of the star. I am a planetary astrophysicist[3]. Admittedly, this is a title that I made up because I wanted something that actually described what I do. I study the elements within stars, their patterns, and how they are connected to planets.

I created an enormous database of stars and their elemental compositions. Some of those stars have planets orbiting them; others don’t. When a star has an orbiting planet, it could be the smaller rocky type, a large gas one, or both. However, not every star can have a giant Jupiter-sized planets – since these planets require a huge amount of elements and materials to form.

Together with a small team of researchers from Arizona State University, University of California, Riverside, Vanderbilt University and New York University, I used software that searches for complex patterns within stellar data to figure out which stars are likely to have planets orbiting[4] them based only on the star’s chemical composition.

Now, instead of looking through huge all-sky telescope surveys hoping to find a signature of a planet, my team can fast-track the discovery and characterization of planets by analyzing the composition of their host stars. Of the 4,200 stars that we analyzed, we found that approximately 360 stars have a greater than 90% chance of hosting a giant planet. Now we are working to get time on a telescope to test our predictions.

Accelerating exoplanet discovery using chemical fingerprints of stars Stars and planets are chemically linked to one another, since they both form within the same molecular cloud. The raw ingredients within the planet ultimately creates an environment that’s ‘alive’ and conducive to life – or not. NASA/JPL-Caltech[5]

The Hypatia Catalog and its elements

The algorithm we developed uses the chemical composition of stars that we know have orbiting giant planets to determine which combination of elements – or chemical fingerprint – is common to stars that host planets. My team then used this algorithm to look at the chemistry of stars not known to have planets to provide a prediction score that a star is likely to host a planet.

Accelerating exoplanet discovery using chemical fingerprints of stars This is the logo for the Hypatia Catalog showing an artist depiction of Hypatia. Some of the most important elements in stars are listed along the outside. Nahks Tr'Ehnl, CC BY-SA[6]

Light shines from the interior of a star and is absorbed by atoms in its upper layer, creating a stellar spectra. The absorbed wavelengths reveal what type of elements from the periodic table are present. Using a technique called spectroscopy[7], scientists are able to measure the light from the star and measure the amount, or abundance, of those elements. I compiled the largest catalog of elements in nearby stars in the Hypatia Catalog[8]. I named it to honor one of the first known female astronomers who was a powerhouse in 400 A.D.

I use the Hypatia Catalog to understand planets from a more chemical or compositional perspective. Each star is made up of different combinations and quantities of elements, which is reflected in the planets orbiting the star. There can be a huge variety in the chemical composition of planets from their interiors to their surfaces.

Physically detecting exoplanets

There are two primary techniques for finding or detecting exoplanets.

The first is the “radial velocity” technique, which detects when a star wobbles in the presence of a planet with a strong gravitational force.

Another strategy is to look for a “blip” in the light a star emits, which happens when a planet moves in front of the star (with respect to the Earth) and actually dims the stellar light. Both of these methods look for ways that the planet influences the star. However, it’s difficult to detect planets because they are so small compared with their star – it would be like trying to observe a person being influenced by a raindrop.

The radial velocity and “blip” methods look at the physical relationship between a star and a planet. These are important because they determine the temperature, orbit and dynamics that exoplanet scientists use to define whether a planet may be habitable. However, none of these detection methods take into account what the star and planet are made of. And yet, understanding the composition of the planet is vital to predicting whether it is habitable.

Accelerating exoplanet discovery using chemical fingerprints of stars An artist’s impression of how common planets are around the stars in the Milky Way. The planets, their orbits and their host stars are all vastly magnified. ESO/M. Kornmesser, CC BY-ND[9][10]

Planetary composition is key to habitability

The planet Earth is “alive” – it moves and shifts in a complex way. The surface conditions, like temperature and weather, are maintained by relying on the movement of the continents, for example by plate tectonics[11]. The cycling of different elements or molecules, like the oxygen-carbon dioxide cycle[12], helps organisms breathe. In order for exoplanets to truly be habitable for life, basic elements must be present within the planet to make sure that these key processes happen.

We exoplanetary scientists don’t currently have the technology to directly observe the surface or interior of a planet outside of our Solar System. This is partially because planets are so small compared to their star, so we’d need high-powered telescopes. It is also because planets don’t shine or emit their own light.

Therefore, my colleagues and I use the stellar composition as a proxy for the planet’s makeup. The algorithm that we developed[13] is a unique one, because it looks at the elemental link between a star and its planet from the very beginning. This makes the approximately 360 likely giant planet host stars we found even more remarkable, because they were identified by the chemical fingerprint.

As part of this research published[14] in The Astrophysical Journal, we studied a variety of different elements, up to 16 at a time. We wanted to see how those elements influenced each other and which were the most important for planet detection and possible formation.

We found that carbon, oxygen, sodium and iron were the most important elements when predicting that a star had a giant planet. Carbon, oxygen and iron are all very important elements when it comes to building rocky and or gas planets. However, we were surprised to discover that sodium also seemed to be a critical ingredient of stars that form giant planets. Sodium is not considered to be a major planet-forming element within the Solar System.

For practical reasons we didn’t use the algorithm to look at Earth-like planets. Rather we focused our study, and trained our algorithm, on big gaseous planets where humans couldn’t survive. Most of the exoplanets that astronomers have discovered to date have sizes similar to Neptune or Jupiter because they are easier to detect.

However, as new missions like TESS[15] and CHEOPS[16] discover smaller, Earth-sized planets, we will have more data with which to train the algorithm to look for rocky planets like Earth.

[ Thanks for reading! We can send you The Conversation’s stories every day in an informative email. Sign up today.[17] ]


  1. ^ huge clouds of dust and gas collapse (
  2. ^ each cloud has a unique composition (
  3. ^ planetary astrophysicist (
  4. ^ which stars are likely to have planets orbiting (
  5. ^ NASA/JPL-Caltech (
  6. ^ CC BY-SA (
  7. ^ spectroscopy (
  8. ^ Hypatia Catalog (
  9. ^ ESO/M. Kornmesser (
  10. ^ CC BY-ND (
  11. ^ plate tectonics (
  12. ^ oxygen-carbon dioxide cycle (
  13. ^ algorithm that we developed (
  14. ^ this research published (
  15. ^ TESS (
  16. ^ CHEOPS (
  17. ^ Thanks for reading! We can send you The Conversation’s stories every day in an informative email. Sign up today. (

Authors: Natalie Hinkel, Planetary Astrophysicist, Senior Research Scientist at the Southwest Research Institute and Co-Investigator for the Nexus for Exoplanet System Science (NExSS), Arizona State University

Read more

Metropolitan republishes selected articles from The Conversation USA with permission

Visit The Conversation to see more

Entertainment News

Phish’s 2018 Fall Tour to Conclude with Four Performances at MGM Grand Garden Arena

LAS VEGAS (May 15, 2018) – Phish, the American rock band known worldwide for its dedicated fan base, recently announced a 14-date Fall tour which will conclude in Las Vegas with four performances at...

Blane Ferguson - avatar Blane Ferguson

Dave Damiani and The No Vacancy Orchestra are “Bending The Standard”

Tina Sinatra, Dave Damiani & Landau Murphy Jr. celebrate 100 years of Frank Sinatra in Los Angeles There have been stories about independent filmmakers, but how about the independent big band...

Tom Estey - avatar Tom Estey

Billboard Chart-Topping Saxophonist VANDELL ANDREW Returns With New Single

From the vantage point of 30, his age and the name of his infectious, sensually grooving new full length album, Vandell continues to be fueled by the impressive roar of accolades and achievements th...

Metropolitan Digital - avatar Metropolitan Digital

Metropolitan Business News

Office Cleaner Takes Ownership of the Neglected Dishwasher

In an office that a dishwasher is being used communally, it is pretty difficult to set rules on how a certain appliance needs to be taken cared of. A dishwasher is a responsibility of no one until you...

News Company - avatar News Company

Amazing tips to become a successful trader

Everyone is working very hard to secure their financial freedom. Most of the people find it hard to support their family even after having a 9-5 day job. For this very reason, people often look for ...

News Company - avatar News Company

Best Practice For Young Professionals Working Through HR Internships

The industry of human relations is vitally important to the health and prosperity of a business.   Whether they are operating in textile manufacturing, accounting, sports, IT development or hospit...

News Company - avatar News Company

4 Easy Steps To Gaining SEO Momentum For Your Business

SEO (search engine optimisation) does not have to be a tiresome and overbearing exercise that diverts attention away from the core functions of a business.   SEO Shark affirms this as a smart and ...

News Company - avatar News Company

How to Manage An SEO Project On Limited Funds

SEO operators don’t need thousands upon thousands of dollars to become successful.   What SEO practitioners needs more than ever is the skills and diligence to identify problems that are acting a...

News Company - avatar News Company

An Introduction To Coworking For Australian Business Owners

Advancing technology is bringing with it great advantages in communications and networking, and to survive in business you need to keep up. With the rate at which everything changes these days, that...

News Company - avatar News Company


New Baggage Regulations to Help Aussie Parents Travel with Infants

Travelling around the globe has never been easy, especially when infants tag along for the trip. One of the main issues that parents often have to deal with is the need to bring extra item...

News Company - avatar News Company

Maya Beach Opens to Tourists

Despite recent reports that Southern Thailand's famous Maya Beach will close for three months this year, in fact no decision to this effect has been made by Thai authorities. Phi Phi Nati...

Maevadi Rosenfeldt - avatar Maevadi Rosenfeldt


SKYN®, Australia’s best-selling condom*, today launches its very first SKYN® Places of Intimacy Guide.   Curated in partnership with GQ Magazine and Conde Nast, the Guide features 30 lux...

SKYN - avatar SKYN