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Unraveling the brown dwarf desert: four new discoveries and a unifying period-coded picture

We present four newly validated transiting brown dwarfs identified through TESS photometry and confirmed with high-precision radial velocity measurements obtained from the FEROS and PLATOSpec spectrographs. Notably, three of these companions exhibit orbital periods exceeding 100 days, thereby expand...

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Main Authors: Šubjak, Ján (Author) , Brahm, Rafael (Author) , Lipták, Jozef (Author) , Eberhardt, Jan (Author) , Pinto, Marcelo Tala (Author) , Casewell, Sarah L. (Author) , Henning, Thomas (Author) , Hesse, Katharine (Author) , Trifonov, Trifon (Author) , Jordán, Andrés (Author) , Rojas, Felipe I. (Author) , Vítková, Michaela (Author) , Salinas, Helem (Author) , Boyle, Gavin (Author) , Suc, Vincent (Author) , Antonucci, Luca (Author) , Bernacki, Krzysztof (Author) , Briceño, César (Author) , Collins, Karen A. (Author) , Fernández, Jorge Fernández (Author) , Gill, Samuel (Author) , Janík, Jan (Author) , Law, Nicholas (Author) , Mann, Andrew W. (Author) , McCormac, James (Author) , Popowicz, Adam (Author) , Sebastian, Daniel (Author) , Skarka, Marek (Author) , Václavík, Ján (Author) , Vanzi, Leonardo (Author) , West, Richard G. (Author) , Wilkin, Francis P. (Author) , Ziegler, Carl (Author)
Format: Article (Journal)
Language:English
Published: May 2026
In: Astronomy and astrophysics
Year: 2026, Volume: 709, Pages: 1-20
ISSN:1432-0746
DOI:10.1051/0004-6361/202558244
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202558244
Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2026/05/aa58244-25/aa58244-25.html
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Author Notes:Ján Šubjak, Rafael Brahm, Jozef Lipták, Jan Eberhardt, Marcelo Tala Pinto, Sarah L. Casewell, Thomas Henning, Katharine Hesse, Trifon Trifonov, Andrés Jordán, Felipe I. Rojas, Michaela Vítková, Helem Salinas, Gavin Boyle, Vincent Suc, Luca Antonucci, Krzysztof Bernacki, César Briceño, Karen A. Collins, Jorge Fernández Fernández, Samuel Gill, Jan Janík, Nicholas Law, Andrew W. Mann, James McCormac, Adam Popowicz, Daniel Sebastian, Marek Skarka, Ján Václavík, Leonardo Vanzi, Richard G. West, Francis P. Wilkin, and Carl Ziegler
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Summary:We present four newly validated transiting brown dwarfs identified through TESS photometry and confirmed with high-precision radial velocity measurements obtained from the FEROS and PLATOSpec spectrographs. Notably, three of these companions exhibit orbital periods exceeding 100 days, thereby expanding the sample of long-period transiting brown dwarfs from four to seven systems. The host stars of the long-period brown dwarfs show mild subsolar metallicity. These discoveries highlight the expansion of the metal-poor long-period distribution and help us better understand the brown dwarf desert. In our comparative analysis of eccentricity and metallicity demographics, we utilized catalogs of long-period giant planets, brown dwarfs, and low-mass stellar companions. After accounting for tidal influences, the eccentricity distribution aligns with that of low-mass stellar binaries, presenting a different profile than that observed within the giant planet population. Additionally, the metallicity of the host stars reveals a noteworthy trend: Short-period transiting brown dwarfs are predominantly associated with metal-rich stars, whereas long-period brown dwarfs are more often found around metal-poor stars, thus demonstrating statistical similarities to low-mass stellar hosts. This trend has been previously observed in studies of hot and cold Jupiters and points to a period-coded mixture of channels. A natural explanation is that most brown dwarfs originate from fragmentation at wider separations, with long-period systems retaining this stellar-like imprint, while only those embedded in massive, long-lived metal-rich protoplanetary disks are efficiently delivered and stabilized to short orbits.
Item Description:Online veröffentlicht: 08. Mai 2026
Gesehen am 18.08.2026
Physical Description:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/202558244

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