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Peer-reviewedCC BY 4.0Astronomy & Astrophysics

The Galah survey and symbiotic stars

  • Ulisse Munari1
  • Paolo Valisa1,2
  • Nicola Masetti3,4
  • Massimo Fiorucci1,2
  • Manica Perko5
  • Bor Jamnik5
  • Gregor Traven5
  • Andrea Frigo2
  • Joss Bland-Hawthorn6
  • Sven Buder7
  • Andrew R. Casey8,9
  • Gayandhi M. De Silva10,11
13 more authors
  • Pradosh B. Das12
  • Ken C. Freeman7
  • Michael R. Hayden6
  • Janez Kos5
  • Geraint F. Lewis6
  • Jane Lin7
  • Sarah L. Martell13
  • Katharine J. Schlesinger7
  • Sanjib Sharma14
  • Jeffrey D. Simpson13
  • Dennis Stello6,13
  • Daniel B. Zucker12,15
  • Tomaž Zwitter5
15 affiliations
  1. 1INAF Osservatorio Astronomico di Padova
  2. 2ANS Collaboration, c/o Astronomical Observatory
  3. 3INAF – Osservatorio di Astrofisica e Scienza dello Spazio
  4. 4Departamento de Ciencias Físicas, Universidad Andrés Bello
  5. 5Faculty of Mathematics and Physics, University of Ljubljana
  6. 6Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney
  7. 7Research School of Astronomy & Astrophysics, Australian National University
  8. 8Monash Centre for Astrophysics, Monash University
  9. 9School of Physics and Astronomy, Monash University
  10. 10Australian Astronomical Optics, Faculty of Science and Engineering, Macquarie Univ.
  11. 11Macquarie University Research Centre for Astronomy, Astrophysics & Astrophotonics
  12. 12School of Mathematical and Physical Sciences, Macquarie University
  13. 13School of Physics, UNSW
  14. 14Space Telescope Science Institute
  15. 15Macquarie University Research Centre for Astrophysics and Space Technologies
Open at sourceDOICite

Abstract

We report the discovery, validation, and characterization of 44 new symbiotic stars (SySts) accreting at the lowest detectable levels (L acc ≲3 L ⊙ ). Candidates were initially selected from the Galah survey among non-pulsating M-type red giants exhibiting H α excess. Between 2021 and 2025, these targets were subjected to intensive multi-wavelength campaigns, including ground-based, high-resolution Echelle spectroscopy over 544 nights, multi-epoch flickering searches down to 1 mmag, and UV/X-ray observations with the Swift satellite. Our high-resolution spectra allowed for a detailed investigation of H α flux and line-profile variability. Crucially, the radial velocities measured for the M-giant components yielded reliable spectroscopic orbits for 22 objects and preliminary orbits for an additional eight, corroborated by binary-induced modulations in ASAS-SN photometry. Measured accretion levels vary by factors of up to 20×, emphasizing the need for high-sensitivity, long-term monitoring. Swift X-ray data exclude neutron star companions in all targets, consistent with predominance of white-dwarf degenerates in known SySts. Combined with the 33 objects from Paper I, this sample of 77 new SySts significantly exceeds the number of previously known, accreting-only Galactic symbiotic stars, constituting the bulk of the low-accretion (LowAcc) variety discovered to date and representing >10% of all known SySts in the Galaxy. As SySts likely spend most of their lifetimes in LowAcc faint states, characterizing this population is essential for estimating the total Galactic SySt population and evaluating the role of SySts as Type Ia supernova progenitors or sources of UV excess in elliptical galaxies.

Versions

Related

  1. The Galah survey and symbiotic stars. II. Discovery, validation, and intensive follow-up of 44 new systems accreting at the lowest detectable levels
    U. Munari, P. Valisa, N. Masetti +22
    arXivPreprintCC BY 4.0Full textSolar & stellar physicsarXiv
  2. Let Sleeping Stars Li: Mapping Turnoff Lithium, the Lithium Dip, & Testing Standard Model Predictions in GALAH DR4 Subgiants
    Vincent A. Smedile, Marc H. Pinsonneault
    arXivPreprintCC BY 4.0Full textGalaxiesSolar & stellar physicsarXiv
  3. Double Trouble: How Unresolved Spectroscopic Binary Stars Skew GALAH DR4 Stellar Parameters
    Yani Lach, Sven Buder, Gregor Traven
    arXivPreprintCC BY 4.0Full textGalaxiesSolar & stellar physicsarXiv
  4. Exploring the Long-term Temporal Variability in Polarization through Multiepoch Optical Spectropolarimetry. II. A Sample of Symbiotic and Red Giant Stars
    Arijit Maiti, Ruchi Pandey, Sube Singh Gurjar +1
    The Astronomical JournalPeer-reviewedCC BY 4.0Full textSolar & stellar physicsCrossref
  5. Exploring the long-term temporal variability in polarization through multi-epoch optical spectro-polarimetry - Part II: A sample of symbiotic and red-giant stars
    Arijit Maiti, Ruchi Pandey, Sube Singh Gurjar +1
    arXivPreprintCC BY-NC-ND 4.0Full textSolar & stellar physicsarXiv

Cite

BibTeXRIS
BibTeX
@article{munari2026galah,
  title = {{The Galah survey and symbiotic stars}},
  author = {Ulisse Munari and Paolo Valisa and Nicola Masetti and Massimo Fiorucci and Manica Perko and Bor Jamnik and Gregor Traven and Andrea Frigo and Joss Bland-Hawthorn and Sven Buder and Andrew R. Casey and Gayandhi M. De Silva and Pradosh B. Das and Ken C. Freeman and Michael R. Hayden and Janez Kos and Geraint F. Lewis and Jane Lin and Sarah L. Martell and Katharine J. Schlesinger and Sanjib Sharma and Jeffrey D. Simpson and Dennis Stello and Daniel B. Zucker and Tomaž Zwitter},
  journal = {Astronomy \& Astrophysics},
  year = {2026},
  month = nov,
  doi = {10.1051/0004-6361/202660724},
  url = {https://www.aanda.org/10.1051/0004-6361/202660724},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - The Galah survey and symbiotic stars
AU  - Ulisse Munari
AU  - Paolo Valisa
AU  - Nicola Masetti
AU  - Massimo Fiorucci
AU  - Manica Perko
AU  - Bor Jamnik
AU  - Gregor Traven
AU  - Andrea Frigo
AU  - Joss Bland-Hawthorn
AU  - Sven Buder
AU  - Andrew R. Casey
AU  - Gayandhi M. De Silva
AU  - Pradosh B. Das
AU  - Ken C. Freeman
AU  - Michael R. Hayden
AU  - Janez Kos
AU  - Geraint F. Lewis
AU  - Jane Lin
AU  - Sarah L. Martell
AU  - Katharine J. Schlesinger
AU  - Sanjib Sharma
AU  - Jeffrey D. Simpson
AU  - Dennis Stello
AU  - Daniel B. Zucker
AU  - Tomaž Zwitter
PY  - 2026
DA  - 2026/11/03
JO  - Astronomy & Astrophysics
DO  - 10.1051/0004-6361/202660724
UR  - https://www.aanda.org/10.1051/0004-6361/202660724
AB  - We report the discovery, validation, and characterization of 44 new symbiotic stars (SySts) accreting at the lowest detectable levels (L acc ≲3 L ⊙ ). Candidates were initially selected from the Galah survey among non-pulsating M-type red giants exhibiting H α excess. Between 2021 and 2025, these targets were subjected to intensive multi-wavelength campaigns, including ground-based, high-resolution Echelle spectroscopy over 544 nights, multi-epoch flickering searches down to 1 mmag, and UV/X-ray observations with the Swift satellite. Our high-resolution spectra allowed for a detailed investigation of H α flux and line-profile variability. Crucially, the radial velocities measured for the M-giant components yielded reliable spectroscopic orbits for 22 objects and preliminary orbits for an additional eight, corroborated by binary-induced modulations in ASAS-SN photometry. Measured accretion levels vary by factors of up to 20×, emphasizing the need for high-sensitivity, long-term monitoring. Swift X-ray data exclude neutron star companions in all targets, consistent with predominance of white-dwarf degenerates in known SySts. Combined with the 33 objects from Paper I, this sample of 77 new SySts significantly exceeds the number of previously known, accreting-only Galactic symbiotic stars, constituting the bulk of the low-accretion (LowAcc) variety discovered to date and representing >10% of all known SySts in the Galaxy. As SySts likely spend most of their lifetimes in LowAcc faint states, characterizing this population is essential for estimating the total Galactic SySt population and evaluating the role of SySts as Type Ia supernova progenitors or sources of UV excess in elliptical galaxies.
SN  - 0004-6361
SN  - 1432-0746
ER  -