LAUNCHED XTgrid Sandbox: Online spectral analyses with Tlusty or CMFGEN models!

Recent Projects

  • July 07, 2021 1/5

    The first heavy-metal hot subdwarf composite binary SB 744

    A&A, 2021, 653, A3, 11TC43IV

    A radial velocity follow-up of the long-period sdOB+G1V type spectroscopic binary SB 744 revealed strong lines of fluorine and lead in the optical spectrum of the sdOB star and ...

  • February 05, 2022 2/5

    Orbital and atmospheric parameters of two O-type subdwarf binaries: BD-11° 162 and Feige 80

    A&A, 2022, 658, A122, 22EZZ74T

    Using high-resolution spectra the orbital and atmospheric parameters of BD-11° 162 and Feige 80 have been solved. Masses of the companions and the sdOs were obtained, and the ...

  • February 09, 2023 3/5

    An 18.9-minute Blue Large-Amplitude Pulsator Crossing the "Hertzsprung Gap" of Hot Subdwarfs

    Nature, 2023, Volume 7, 223UMVVTX

    Blue large-amplitude pulsators (BLAPs) represent a new and rare class of hot pulsating stars with unusually large amplitudes and short periods. Up to now, only 24 confirmed BLAPs ...

  • August 23, 2023 4/5

    Unveiling the Evolutionary State of Three B Supergiant Stars: PU Gem, ϵ CMa, and η CMa

    Galaxies, 2023, Vol. 11, issue 5, p. 93.M1DE05

    We aim to combine asteroseismology, spectroscopy, and evolutionary models to establish a comprehensive picture of the evolution of Galactic blue supergiant stars (BSG). To start ...

  • February 09, 2024 5/5

    A seven-Earth-radius helium-burning star inside a 20.5-min detached binary

    Nature Astronomy, 2024, acceptedY75AKG

    Binary evolution theory predicts that the second common envelope (CE) ejection can produce low-mass (0.32 - 0.36 solar mass) subdwarf B (sdB) stars inside ...


Astroserver is a private, community supported non-profit organization with affordable solutions in research astronomy. The team offers expertise mainly in stellar astrophysics, spectroscopy, non-LTE model atmosphere calculations, assistance with publications and media content production, and help with service observations. These services are similar to the tasks of post-doctoral and graduate researchers. Therefore, our activity can be integrated into the programme of graduate schools and research institutes. To wrap-up: Astroserver is your "occasional post-doc".

The main goal of the Astroserver Team is to provide precise and reliable measurements of stellar atmospheric parameters in a consistent way across the Hertzsprung-Russell Diagram and make it accessible to everyone. The accuracy of these solutions depends on the choice of the model, the quality of input atomic data and observations. Therefore, our Team continuously improves the models and revise the atomic data input by analyzing high quality observations of standard objects. Beyond the main mission the Team is also keen on finding solutions to challenging problems on the frontiers of applied stellar spectroscopy.

Interested researchers: Please consider our services in the budget plan of your grant applications! Upon request we contribute to such proposals free of charge.

Feel free to contact us for more information!

Research Highlights
  • 2016

    PB 3877: A new hypervelocity binary

    A team of astronomers at the Friedrich Alexander University, Erlangen-Nürnberg (FAU, Germany) in collaboration with researchers from the California Institute of Technology (Caltech, USA), has discovered a binary star (PB 3877) that is moving nearly at the escape velocity of our Galaxy.

  • 2021

    The first heavy-metal hot subdwarf composite binary SB 744

    A radial velocity follow-up of the long-period sdOB+G1V type spectroscopic binary SB 744 revealed strong lines of fluorine and lead in the optical spectrum of the sdOB star and subsolar metallicity in the G1V companion. With high-quality observations and Gaia astrometric data, we aim at measuring the ...

  • 2020

    TESS observations of the interesting pulsating subdwarf B star CD-28° 1974

    From TESS observations we have discovered CD-28° 1974 to be a pulsating subdwarf B star which has an unusual gravity(g)-mode asymptotic sequence indicating that CD-28° 1974’s structure is somewhat different from typical sdBV stars.

  • 2017

    A FEROS survey of hot subdwarf stars

    We have initiated a small survey of twenty hot subdwarfs using the Fiber-fed Extended Range Optical Spectrograph (FEROS) and the 2.2-m telescope at La Silla. The sample includes apparently single objects as well as hot subdwarfs paired with a bright, unresolved companion extracted from our GALEX catalogue of hot subdwarf stars (Vennes et al., 2011; Nemeth et al., 2012). As expected (Kawka et al., 2015; Kupfer et al., 2015), the fraction of radial velocity variables ...


We are currently looking at ways how to generalize and make accessible a self-service tool for the spectroscopic analysis of composite spectra. The reasons to make efforts in this direction are that many stars are in binaries and binaries provide not only more, but, in some cases, key information to astronomers. This information, however, come at a price. While the analyses of single stars are challenging, binaries and multiple objects prove even more than twice as difficult and tedious.

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