Amateur astronomers across several countries helped confirm gas giant TOI-4465 b

Astronomers at the University of New Mexico detected a dense gas giant exoplanet around 400 light-years away from Earth.

The first orbiting data from NASA’s Transiting Exoplanet Survey Satellite picked up 12 hours of dimmed starlight, but to prove the existence of the exoplanet, they needed another full orbit.

This task could not be undertaken by just one observatory. It took the efforts of 24 citizen scientists in 10 different countries to observe TOI-4465 b for 12 hours.

Seeing one 12-hour shadow in space

The discovery of the celestial object was made possible by a very short signal in the photometric observations from satellites.

When scientists analyzing the light curves captured by the TESS satellite saw one small period of dimmed starlight that lasted nearly 12 hours, it indicated the transit of an enormous object across a star that resembles our Sun.

A single transit does not provide known orbital elements.

The orbital period of the discovered planet was estimated to be longer than 13 days because TESS observes a certain part of the sky for 27 days.

Why single-location telescopes fail to capture long transits

Identification of long-period planets involves several challenges in observation.

Since TOI-4465 b takes 102 days to complete an orbit around its star, three transit events are expected per year and require a minimum of 12 hours of continuous observation.

Observation cannot be done using a single telescope at any ground-based location.

The rotation of the Earth, adverse weather conditions, and daytime would disrupt the observation over the 12 hours.

The transit window was predicted by astronomers at the University of New Mexico.

By measuring the gravitational pull on the star, the information that the transit would occur between August 9 and August 12, 2022, was obtained.

Torch-passing observation across 10 countries

Scientists organized a global relay race to keep track of the trail.

To make sure that there was no break in the visibility, 24 people selected from 10 different nations equipped themselves with personal telescopes connected to the Unistellar network and accessed by follow-up teams.

The observations were handed over from observer to observer as the Earth kept rotating.

The observations of Japan, New Zealand, Europe, and the United States were taken in turn, thus forming a dataset for 12 hours of light measurement.

Using similar digital technologies, it was possible to combine all the light curves from individual participants into one master observation file.

Measurement of a dense and temperate gas giant planet

Observational datasets have yielded remarkable information regarding the nature of the exoplanet.

Further observations proved that TOI-4465 b has about six times the mass of Jupiter but a radius that is only 25 percent wider than Jupiter’s.

A high mass and small radius result in an exceptionally dense composition.

Unlike bloated hot Jupiter-type planets that orbit very close to their host stars, this one has temperate atmospheric conditions due to its longer orbital period of 102 days.

It is a planet lying somewhere between the definitions of hot and cold gas giants.

According to the SETI Institute, the low orbital eccentricity keeps the temperature moderate, thereby providing an important reference point for the study of planet evolution around metal-poor stars.

How global networks facilitate exoplanet science

The participation of citizen science expands the potential of space telescopes.

As long as long-period planet observations happen very rarely and cannot be detected twice using orbiting telescopes, it is extremely important to have global networks in order to gather all necessary data about these candidates.

Automated telescopes facilitate studies by citizen scientists and scientific establishments.

Thanks to the use of tracking tools for amateur scientists, global scientific institutions can monitor what happens in space but cannot do it independently.

The teamwork involved in recent planet hunting sets a good example for the future.

Because space telescopes detect thousands of different transits in a year, it is likely that global citizen networks will play an essential role in the process in the future.