Discovering new worlds with quantitative spectroscopy

Astronomers from the Leibniz Institute for Astrophysics Potsdam (AIP) and the Vatican Observatory (VO) teamed as much as spectroscopically survey greater than 1,000 vibrant stars that doubtlessly host exoplanets.

The staff presents exact values of 54 spectroscopic parameters per star within the first of a sequence of papers within the journal Astronomy & Astrophysics and launched all its information to the scientific group. This unprecedented giant variety of parameters will likely be important to deciphering the stellar gentle and discovering connections between the celebrities’ properties and their probably nonetheless unknown planets.

Stars inform tales about themselves, and typically about their undiscovered planets. Their language is gentle; it reveals many bodily properties of a star, together with its temperature, strain, movement, and chemical composition. Researchers analyze the sunshine with a technique known as quantitative absorption spectroscopy.

Telescopes seize starlight and spectrographs break it up by wavelength right into a rainbow-like spectrum which is the star’s gentle fingerprint. When astronomers know these parameters exactly, they’ll use them to check their theoretical fashions of stars. This typically reveals that the fashions have some shortcomings, or that observations of stellar spectra are nonetheless too imprecise.

However typically, it reveals {that a} star has a shocking story for astronomers. That’s what motivated this staff to make an ultra-precise survey of potential planet-hosting stars.

“As a result of stars and their planets type collectively, the query arose whether or not the existence of sure chemical parts in a stellar environment, or their isotopic or abundance ratios, is indicative of a planetary system,” explains Prof. Klaus G. Strassmeier, lead writer, director at AIP and principal investigator of the survey.

Astronomers have hypothesized that the quantities of various chemical parts inside a star might trace that the star has terrestrial planets (rocky worlds like Earth or Mars), might recommend ages for these planets, and will even present clues that the star has “eaten” a few of its planets. It will want additional investigation, and the now launched information lay the foundations for such research.

Of the over 5,000 confirmed exoplanets (planets orbiting different stars than the Solar), 75% have been found from space by observing a star’s gentle being diminished due to a planet transiting in entrance of it. NASA’s Transiting Exoplanet Survey Satellite tv for pc (TESS) mission found exoplanets simply this fashion.

It yielded extra exoplanets when observing these elements of the sky furthest from the ecliptic (the aircraft by which the Earth orbits the Solar), known as the ecliptic poles. Observatories within the northern hemisphere can observe the Northern Ecliptic Pole, and this survey of potential planet-hosting stars inside this area is called the Vatican-Potsdam Northern Ecliptic Pole (VPNEP) survey.

The survey targeting the richest observing discipline of TESS, an space of the sky roughly 4,000 occasions the dimensions of the full moon. All roughly 1,100 doubtlessly planet-hosting stars on this discipline have been investigated. As much as 1.5 hours of telescope time was required to collect sufficient of a star’s gentle to make a single high-quality spectrum. With a number of visits per star, it took 5 years to acquire the survey information.

The survey made use of telescopes at two websites: In Arizona, the VO’s Alice P. Lennon Telescope and Thomas. J. Bannan Astrophysics Facility (Vatican Superior Expertise Telescope or VATT) fed gentle to the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) and took spectra of dwarf stars with unprecedented precision. On Tenerife, the AIP’s STELLA (STELLar Exercise) Observatory used the STELLA Echelle Spectrograph to seize gentle of large stars with decrease, however nonetheless excessive, precision.

Dr. Martina Baratella, one in every of AIP’s postdoctoral researchers concerned within the survey, feedback, “The spectra revealed parts which can be among the many most troublesome to watch.” Abundance ratios like carbon to iron or magnesium to oxygen trace in the direction of the existence and age of in any other case unseen rocky planets. Prof. Strassmeier provides, “Whereas it should take time to completely analyze the information from the survey, we anticipate quickly to announce subsequent discoveries.”