top of page
  • Writer's pictureMatt Russell

222 - Exoplanets with Linn Boldt-Christmas

Updated: Feb 19, 2021

This week Julio and Matt record the show live with Linn Boldt-Christmas for a fun look at exoplanets and more!!!

“Om kunskapen icke alltid går i det godas och rättas tjänst, så är okunnigheten dock alltid våldets och lidelsernas säkra byte”
Anders Jonas Ångström

Ångström was a pioneer in the field of spectroscopy, and he is also well known for his studies of astrophysics, heat transfer, terrestrial magnetism, and the aurora borealis. In 1852, Ångström formulated in Optiska undersökningar (Optical investigations),[12] a law of absorption, later modified somewhat and known as Kirchhoff's law of thermal radiation.[citation needed]

In 1868, Ångström created a chart of the spectrum of sunlight, in which he expressed the wavelengths of electromagnetic radiation in the electromagnetic spectrum in multiples of one ten-millionth of a millimetre (or 10−7 mm.). Because the human eye is sensitive to wavelengths from about 4000 to 7000 (visible light), that choice of unit supported sufficiently accurate measurements of visible wavelengths without resorting to fractional numbers, Ångström's chart and table of wavelengths in the solar spectrum became widely used in solar physics, which adopted the unit and named it after him. It subsequently spread to the rest of astronomical spectroscopy, atomic spectroscopy, and subsequently to other sciences that deal with atomic-scale structures.

Exoplanet Special

Nobel Prize for the first Exoplanet and big bang theory…..sort of

This artist’s view shows the hot Jupiter exoplanet 51 Pegasi b, sometimes referred to as Bellerophon, which orbits a star about 50 light-years from Earth in the northern constellation of Pegasus (The Winged Horse). This was the first exoplanet around a normal star to be found in 1995. Twenty years later this object was also the first exoplanet to be be directly detected spectroscopically in visible light.: ESO/M. Kornmesser/Nick Risinger

Three scientists have been awarded the 2019 Nobel prize in physics for groundbreaking discoveries about the evolution of the universe and the exoplanets.

Jim Peebles : Princeton

Phillip James Edwin Peebles OM FRS (born April 25, 1935) is a Canadian-American astrophysicist, astronomer, and theoretical cosmologist who is currently the Albert Einstein Professor Emeritus of Science at Princeton University He is widely regarded as one of the world's leading theoretical cosmologists in the period since 1970, with major theoretical contributions to primordial nucleosynthesis, dark matter, the cosmic microwave background, and structure formation.

However Swiss astronomers Michel Mayor and Didier Queloz share the other half of the prize for their discovery of the first planet beyond our solar system, 51 Pegasi B, a gas giant about 150 times more massive than Earth with balmy surface temperature of about 1,000C. only thing is it isn’t the first exoplanet.

What about the astronomers who discovered the actual first exoplanet, Dale Frail and Aleksander Wolszczan, years earlier, in 1992. It was a system around a pulsar with three planets, discovered in radio, and is believed the planets were formed after the star after it died. Obviously an unusual system, but the one that got the Nobel Prize is not the first known exoplanet!

Before we go on here, of course, Mayor and Queloz deserve the prize, there work sparked the exoplanet gold rush, with 4000 exoplanets discovered since.

1952, more than 40 years before the first hot Jupiter was discovered, Otto Struve (podcast 132) wrote that there is no compelling reason why planets could not be much closer to their parent star than is the case in the Solar System and proposed that Doppler spectroscopy and the transit method could detect super-Jupiters in short orbits

1917 - The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. A polluted White Dwarf, that was reanalysed years later to reveal an exoplanet in the data.van Maanen's Star, which is about 14 light-years away, is the closest white dwarf to Earth that is not part of a binary system

1988 by the Canadian astronomers Bruce Campbell, G. A. H. Walker, and Stephenson Yang of the University of Victoria and the University of British Columbia. Cautious but their radial-velocity observations suggested that a planet orbits the star Gamma Cephei. astronomers remained skeptical for several years about this and other similar observations. subsequent work in 1992 again raised serious doubts. But finally, in 2003, improved techniques allowed the planet's existence to be confirmed

9 January 1992, radio astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two planets orbiting the pulsar PSR 1257+12. This discovery was confirmed and is generally considered to be the first definitive detection of exoplanets. Follow-up observations solidified these results, and confirmation of a third planet in 1994 revived the topic in the popular press.

These pulsar planets are thought to have formed from the unusual remnants of the supernova that produced the pulsar, in a second round of planet formation, or else to be the remaining rocky cores of gas giants that somehow survived the supernova and then decayed into their current orbits.

On 6 October 1995, Michel Mayor and Didier Queloz of the University of Geneva announced the first definitive detection of an exoplanet orbiting a main-sequence star, namely the nearby G-type star 51 Pegasi This discovery, made at the Observatoire de Haute-Provence, ushered in the modern era of exoplanetary discovery. Technological advances, most notably in high-resolution spectroscopy, led to the rapid detection of many new exoplanets: astronomers could detect exoplanets indirectly by measuring their gravitational influence on the motion of their host stars. More extrasolar planets were later detected by observing the variation in a star's apparent luminosity as an orbiting planet transited in front of it.

Initially, most known exoplanets were massive planets that orbited very close to their parent stars. Astronomers were surprised by these "hot Jupiters", because theories of planetary formation had indicated that giant planets should only form at large distances from stars. But eventually more planets of other sorts were found, and it is now clear that hot Jupiters make up the minority of exoplanets.


The furthest Exoplanet?

Xinyu Dai and Eduardo Guerras used NASA's Chandra X-ray Observatory to probe for planets in a galaxy a little closer to us — roughly 3.8 billion light-years away — using microlensing from the quasar

An analysis of the lightcurve of the microlensing event PA-99-N2 suggests the presence of a planet orbiting a star in the Andromeda Galaxy (2.54 ± 0.11 Mly)

AS reported on podcast 67 Xinyu Dai and Eduardo Guerras used NASA's Chandra X-ray Observatory to probe for planets in a galaxy a little closer to us — roughly 3.8 billion light-years away — using microlensing from the quasar. The result was astounding. The quasar's light revealed 2,000 unbound planets moving between the galaxy's stars.

These planets range in size from Earth's moon to the planet Jupiter.

Artist's impression of the exoplanet Proxima Centauri b shown as of a arid (but not completely water-free) rocky Super-Earth. This appearance is one of several possible outcomes of current theories regarding the development of this exoplanet, while the actual look and structure of the planet is known in no ways at this time. Proxima Centauri b is the closest exoplanet to the Sun and also the closest potentially habitable exoplanet as well. It orbits Proxima Centauri, a red dwarf with a surface temperature of 3040 K (thus hotter than light bulbs and therefore whiter, as depicted here). The Alpha Centauri binary system is shown in the background.: ESO

Least distant: Proxima Centauri b 4.22 light years Also the closest rocky exoplanet, and closest potentially habitable exoplanet known. As Proxima Centauri is the closest star to the Sun (and will stay so for the next 25,000 years) so this is an absolute record.

Coronagraph of star Fomalhaut showing disk ring and location of extrasolar planet b. creditNASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (University of California, Berkeley), M. Clampin (NASA Goddard Space Flight Center), M. Fitzgerald (Lawrence Livermore National Laboratory), and K. Stapelfeldt and J. Krist (NASA Jet Propulsion Laboratory) -

Least distant directly visible; Fomalhaut b - 25 light-years Also first directly imaged planet at optical wavelength.

Most massive: CD-33 2722b - 31 Jupiter masses, It may actually be too massive to be a planet, and may be a brown dwarf instead.

CD-35 2722 bPlanet StatusConfirmedDiscovered in2011Mass31.0 ( -8.0 +8.0 ) MJ

This artist's depiction shows a white dwarf star; the dead remnants of sun-like stars; vaporizing a minor planet as it orbits around it, causing rocky materials to show up in the spectrum of the star. CfA/Mark A. Garlick -

Least massive: WD 1145+017 b is 0.00067 mass of Earth - like the picture above.

In 1999, Upsilon Andromedae became the first main-sequence star known to have multiple planets.

Kepler-16 contains the first discovered planet that orbits around a binary main-sequence star system

The gap in the Data!!!

We have found and catalogued over 4,500 exoplanets! But there is a small problem, we have a giant catalogue, but most of these planets we know very little about, but why? and how does Cheops help?

  • Using the transit method: the minuscule dimming of the star as a planet passes in front you can infer the radius of that object,

  • Using Radial velocity method, how much a star is being pulled about by the orbiting planets using Doppler shifts of light (colour change as the star is being pulled towards or away from us) you can infer the mass of that planet.

If you know both the mass and the radius you can start to work out the density of a planet, so tantalising information on the physical nature of the planet can be obtained.

Despite the two amazing space missions that looked at transit searches in CNES/ESA CoRoT and NASA’s Kepler and the past two decades of high-precision radial velocity measurement from the ground the number of exoplanets in the 1 to 30 x Earth earth mass range for which both mass and radius are accurately known, is pretty small.

This is because masses cannot be measured accurately enough by the current Doppler methods, as they are simply too faint to allow the required precision in radial velocity to be reached. We have been left with two populations of exoplanets, one for which we know the mass and one for which we know the radius with very little overlap. The goal of CHEOPS is to significantly increase the sample of objects to have both radius and mass measurements so scientists can determine the structure of the planet and also if the planet has an atmosphere! A list of 400-500 targets to look at over the next 3.5 years. All this for Super-Earth planets, Neptune sized down to the mass of Earth with a precision that simply cannot be achieved from the ground, and will be sending this info down via a 1.2 GBit/day downlink, The first data is expected at the beginning of 2020.

Guaranteed Time Observing (GTO) Programme: 80% of the science observing time on CHEOPS is dedicated to the CHEOPS, under the responsibility of the CHEOPS Science Team (chaired by Didier Queloz)

More to come.

Also as the bigger telescopes come online and we can measure these doppler shifts more accurately we will be able to add the Cheops data!!!

  • Hubble Space Telescope and MOST (Canadian very small telescope in space) have also found and confirmed a few planets.

  • The infrared Spitzer Space Telescope has been used to detect transits of extrasolar planets, as well as occultations of the planets by their host star and phase curves

  • The Gaia mission, is using astrometry, measuring a star's position in the sky, and observing how that position changes over time, to determine the true masses of 1000 nearby exoplanets

  • NASA’s TESS, launched in 2018, ESA’s PLATO will launch in 2026 both will also use the transit method.

  • James Webb Space Telescope (JWST) will analyse the atmospheres of the planets that are turned up by all these. “use a small telescope 'to identify', and then a bigger telescope 'to understand' - and that's exactly the kind of process we plan to do," said 2019 Physics Nobel laureate Prof Didier Queloz. Told the BBC

To reinforce that point from last week that ESA has to develop and invent technology for every mission

“When we wanted to test this in the lab we didn't find a single light source in the world that was stable to this precision to allow us to test our telescope - so we had to build one."

Professor Dr Willy Benz an astrophysicist and director of the Physics Institute at the University of Bern. He heads the ESA CHEOPS mission.

NEID exoplanet hunter (pronounced “NOO-id,” rhymes with fluid)

The NN-EXPLORE Exoplanet Investigations with Doppler spectroscopy. For a further twist, it’s a “nested” acronym; the NN comes from NN-EXPLORE, the NASA-NSF (national science foundation) Exoplanet Observational Research partnership.


NEID A new NASA-funded planet-hunting instrument has been installed on the WIYN telescope,(Universities of Wisconsin, Indiana, Yale and the National Optical Astronomy Observatory ((NOAO))) on Arizona’s Kitt Peak. NEID is a spectrometer that is one of the first instruments of its kind with the precision to detect small, terrestrial planets around nearby stars. NEID will also confirm the presence of planets discovered by NASA’s TESS space telescope, and reveal details of their anatomy. Trying to find a world with life on it.

the observatory sits on land of the Tohono O'odham Nation, and NEID's pronunciation evokes a word that roughly translates as "to see" in the Tohono O'odham language

  • radial velocity method, Jupiter, with its immense gravity, causes our home star to move back and forth at roughly 43 feet per second (13 meters per second), whereas Earth causes a more sedate movement of only 0.3 feet per second (0.1 meters per second)

Until now, instruments have typically been able to measure speeds as low as about 3 feet per second (1 meter per second), but NEID belongs to a new generation of instruments capable of achieving about three-times-finer precision. It has the potential to detect and study rocky planets around stars smaller than the Sun. In addition, the scientists and engineers working with the instrument want to use it to demonstrate "extreme precision radial velocity" that could perhaps one day detect planets as small as Earth orbiting around Sun-like stars in the habitable zone, where liquid water could potentially exist on a planet's surface.

Again this is all about combining the measurements from TESS using the transit method, that reveals the size of a planet, but not mass. The radial method finds a planet’s mass but not size, if you know both you get the density and that becomes super interesting!!! managed at NASA by the Exoplanet Exploration Program (ExEP), based at the Jet Propulsion Laboratory in Pasadena, California

The NEID spectrograph was built at the Pennsylvania State University. NSF's National Optical-Infrared Astronomy Research Laboratory (OIR Lab) was responsible for modifications to the WIYN 3.5-meter telescope to accommodate NEID

To add to this

announced on Monday at the 235th meeting of the American Astronomical Society in Honolulu. Tess, has uncovered its first Tatooine-like circumbinary planet — a world that orbits two stars instead of one. he new discovery shows that many more of these exotic systems may be located around bright, nearby stars like those TESS the (Transiting Exoplanet Survey Satellite) is built to study

TOI 1338 b is about 1,300 light-years away in the constellation Pictor. And although one of its stars is slightly larger than our own sun, the other is a tiny red dwarf only 30 percent of the sun’s mass. The two stars also are quite close together, orbiting each other once every 14.6 days. But the planet, estimated to be 6.9 earth mass, TOI 1338 b traces a wider path around the pair, taking about 95 days to complete a single orbit.

orbit should remain stable for at least another 10 million years, but its orbital tilt changes over time.

Although TOI 1338 b currently passes in front of its host stars from our point of view — which is how TESS was able to spot it — after November 2023, the planet's orbit will be too tilted to eclipse these stars for about eight years.

This kind of changing orbital tilt is something that astronomers often see with circumbinary planets. Lead author Veselin Kostov, an astronomer from NASA’s Goddard Space Flight Center said at the conference.

Planet between the sizes of Neptune and Saturn

The acronym "TOI" refers to stars and exoplanets studied by TESS, and is short for: "Transiting Exoplanet Survey Satellite Object of Interest".

Wolf Cukier who has just finished his junior year at Scarsdale High School in New York at NASA Goddard as an intern, “I was looking through the data for everything the volunteers had flagged as an eclipsing binary, a system where two stars circle around each other and from our view eclipse each other every orbit,” Cukier said. “About three days into my internship, I saw a signal from a system called TOI 1338. At first I thought it was a stellar eclipse, but the timing was wrong. It turned out to be a planet.” Cukier co-authored along with scientists from Goddard, San Diego State University, the University of Chicago and other institutions, has been submitted to a scientific journal.

After identifying TOI 1338 b, the research team used a software package called eleanor, named after Eleanor Arroway, the central character in Carl Sagan’s novel “Contact,” to confirm the transits were real and not a result of instrumental artifacts.

There are 4104 confirmed planets, 37 by TESS, and 1517 waiting to be confirmed.

Only 23 Circumbinary planets confirmed found so far.

1993, The first confirmed circumbinary planet (2.5 x Jupiter mass) was found orbiting the system PSR B1620-26, which contains a millisecond pulsar and a white dwarf and is located in the globular cluster M4

2011 KEPLER 16b, 200ly from earth in cygnus, frozen world of rock and gas, about the mass of Saturn. It orbits two stars that are also circling each other, one about two-thirds the size of our sun, the other about a fifth the size of our sun. Each orbit of the stars by the planet takes 229 days, while the planet orbits the system's centre of mass every 225 days; the stars eclipse each other every three weeks or so

NASA’s Kepler and K2 missions previously discovered 12 circumbinary planets in 10 systems, all similar to TOI 1338 b. Observations of binary systems are biased toward finding larger planets, Kostov said. Transits of smaller bodies don’t have as big an effect on the stars’ brightness. TESS is expected to observe hundreds of thousands of eclipsing binaries during its initial two-year mission, so many more of these circumbinary planets should be waiting for discovery.

74 views1 comment

Recent Posts

See All



Thanks for the amazing podcast. I knew already the work of Linn, and I keep learning each time more relevant information. You make exoplanets atmospheres more than fun, This is our future "final frontier" ! Bravo.

bottom of page