Vatican Telescope

Vatican telescope searches for new worlds: here’s what it has found

At the moment, what the stars are made of is being investigated since it is suspected that these bodies host their own exoplanets.

Print Friendly, PDF & Email
Share this Entry

(ZENIT News / Castelgandolfo-Vatican City, 03.21.2023).- Astronomers from the Leibniz-Institute for Astrophysics Potsdam (AIP)  and the Vatican Observatory (VO) teamed up to spectroscopically  survey more than 1000 bright stars which are suspected to host their  own exoplanets. The team — which includes VO astronomers Fr.  Paul Gabor, S.J., Fr. David Brown, S.J., and Fr. Chris Corbally, S.J.,  and VO engineer Michael Franz — now presents precise values of  54 spectroscopic parameters per star in the first of a series of papers  in the journal Astronomy & Astrophysics and releases all its data to the  scientific community. This unprecedented large number of parameters  will be essential to interpreting the stellar light and finding connections  between the properties of stars and their possible planets.

Stars tell stories about themselves, and sometimes about their  undiscovered planets. Their language is light. Starlight reveals many  physical properties of a star, such as its temperature, pressure, motion,  chemical composition, and more. Researchers analyze the light with a  method called quantitative absorption spectroscopy. To do this, telescopes  capture starlight and spectrographs break it down by wavelength into  a rainbow-like spectrum which is the star’s fingerprint of light. When  astronomers know these parameters precisely, they can use them to test  their theoretical models of stars. This often reveals that the models have  some shortcomings, or that observations of stellar spectra are still too  imprecise.

But sometimes, it reveals that a star has a surprising story for  astronomers. That is what motivated this team to carry out an ultra precise survey of possible planet-hosting stars. “Because stars and their  planets form together, the question arose whether the existence of  certain chemical elements in a stellar atmosphere, or their isotopic  or abundance ratios, is indicative of a planetary system,” explains  Prof. Klaus G. Strassmeier, lead author, director at AIP and principal  investigator of the survey.

Astronomers have hypothesized that the  amounts of different chemical elements within a star could hint that  the star has terrestrial planets (rocky worlds like Earth or Mars), could  suggest ages for those planets, and could even provide clues that the star  has “eaten” some of its planets. This needs to be further investigated and  the data now published form the basis for this.

Of the over 5000 confirmed exoplanets (planets orbiting other stars  than the Sun), 75% were discovered from space by observing the light  of stars being reduced because of planets passing in front of them.  NASA’s Transiting Exoplanet Survey Satellite (TESS) mission discovered  exoplanets just this way. It yielded more exoplanets when observing  those parts of the sky furthest from the ecliptic (the plane in which  the Earth orbits the Sun), called the ecliptic poles.

Observatories in the  northern hemisphere can observe the northern ecliptic pole, and this  survey of potential planet-hosting stars within this region is named the Vatican-Potsdam Northern Ecliptic Pole (VPNEP) survey.

The survey concentrated on the richest observing field of TESS, an  area of the sky approximately 4000 times the size of the full moon. All  approximately 1,100 potentially planet-hosting stars in this field were  investigated. Up to 1.5 hours of telescope time was required to catch  enough of a star’s light to make a single high-quality spectrum. With  several visits per star, it took five years to finish the survey.

The survey used telescopes at two sites: In Arizona, the VO’s Alice P.  Lennon Telescope and Thomas. J. Bannan Astrophysics Facility (Vatican  Advanced Technology Telescope or VATT) fed light to the AIP’s Potsdam  Echelle Polarimetric and Spectroscopic Instrument (PEPSI). These  recorded spectra of smaller stars with unprecedented precision. On  Tenerife, the AIP’s STELLA (StellTELLar Activity) Observatory used  the STELLA Echelle Spectrograph to capture light of giant stars with  lesser, but still high, precision.

Dr. Martina Baratella, one of AIP’s postdoctoral researchers involved in  the survey, comments: “The spectra revealed elements that are among  the most difficult to observe.” Abundance ratios like carbon to iron or  magnesium to oxygen hint towards the existence and age of otherwise  unseen rocky planets.

Prof. Strassmeier adds: “While it will take time to fully analyze the data  from the survey, we expect soon to announce subsequent discoveries.”

Fr. Gabor remarks: “Auguste Comte, the founder of French positivism,  once wrote that we would never know what stars were made of. He did  not know that starlight carried the ‘fingerprints’ that would be able to  tell us so much about stars. Creation appears to be made to allow us to  understand it—a parallel to what biblical revelation tells us about how  God wants to be known.”

The key areas of research at the AIP are cosmic magnetic fields and  extragalactic astrophysics. A considerable part of the institute’s  efforts aim at the development of research technology in the fields  of spectroscopy, robotic telescopes, and e-science. The AIP is the  successor of the Berlin Observatory founded in 1700 and of the  Astrophysical Observatory of Potsdam founded in 1874. The latter was  the world’s first observatory to emphasize explicitly the research area of  astrophysics.

The Vatican Observatory (VO) is the successor of observatories  established and supported by the Holy See since 1572. Its headquarters  are at the Pope’s summer residence in Castel Gandolfo. Thanks to  collaboration with the University of Arizona in Tucson, VO has a  telescope on Mt Graham (70 miles or 110 km northeast of Tucson,  10,500 ft or 3200 m above sea level).

Print Friendly, PDF & Email
Share this Entry


Support ZENIT

If you liked this article, support ZENIT now with a donation