SUBSTELLAR
Substellar Science with EUCLID Space Mission

Yesterday, Monday 16 June, was an unforgettable day for the attendees, speakers and organisers of the Vatican Observatory Summer School (VOSS 2025). They had the opportunity to meet Pope Leo XIV at the Consistory Hall in Vatican City.

During the ceremony, the Holy Father addressed them.

In his speech, the Pope said he was pleased to have the opportunity to greet the participants, who are students and scholars from various parts of the world taking part in the School. He offered them his prayerful good wishes, hoping that their experience of living and studying together would be academically and personally enriching and would help them to develop friendships and forms of collaboration that would contribute to the progress of science in the service of our one human family.

SUBSTELLAR PhD students Stella Tsilia and Jun-Yan Zhang attended the meeting. During the handshake, Stella gave the Holy Father an IAC sticker.

An image of the Pontiff talking to students from SUBSTELLAR who are attending VOSS 2025 was released on the front page of Vatican News , the Vatican's official channel.

Clink on the link to read the Address of the Holy Father to the participants of the Summer School of Astrophysics promoted by the Vatican Observatory .

More details on the School at VOSS 2025 .

 

Fifty years ago the search for the first Brown Dwarf (BD) was raging among various teams over the world. After several years of intense studies, in September 1995 the first BD were announced in the Pleiades cluster and as a companion to the bright star Gl229, starting a new era in astrophysics. Since then, the field has grown significantly with thousands of BDs known with different spectral types, ages, and metallicities. However the first truly unambiguous halo BD remain to be identified. Do they exist ? How formation processes of substellar objects differ with metallicity?

Representatives from the SUBSTELLAR project are forming part of the Scientific and Local Organising Committees, and some of them will be attending the conference to present their work.

In this conference, we will celebrate the 30th anniversary of the discovery of the first brown dwarfs and review the most recent substellar studies with special emphasis on metal-poor objects.

1. Discoveries, census, spectral classification, characterisation of very-low mass and substellar populations at different metallicities and ages
2. Evolutionary models and atmospheres of (metal-poor) low-mass stars and BDs
3. Formation processes of very low-mass stars and BDs
4. Review of the latest studies of halo BDs from the ground and space
5. Search for the coolest members of Globular Clusters

This conference will also include a tribute to our colleague and friend Prof Yakiv Pavlenko who passed away at the end of 2024.

Dates: 1-5 September 2025

Venue: The conference will take place at the  hotel Jardin Tecina  located on the island of  La Gomera  in the  Canary Islands (Spain)

Limited to maximum 100 on-site participants

More details at meeting Website  Brown Dwarfs Keep Their Cool: 30 years of Substellar Science

WISEA J181006.18-101000.5 (WISE1810) is the nearest metal-poor ultracool dwarf to the Sun. It has a low effective temperature and has been classified as an extreme early-T subdwarf. However, methane--the characteristic molecule of the spectral class T--was not detected in the previous low-resolution spectrum.

Constraining the metallicity--the abundance of elements heavier than helium-- of these cold objects has been a challenge. Using the 10.4 m Gran Telescopio Canarias, the largest optical-infrared telescope in the world, we collected a high-quality near-infrared intermediate-resolution spectrum of WISE1810, in which 17 ± 6 ppm of methane is clearly detected, while carbon monoxide is absent.

Based on a custom-computed ATMO2020++ model, we estimated an effective temperature of 1000 ± 100 K, a high surface gravity, and a carbon abundance 30 times lower than that of the Sun, implying a metallicity even 50 times lower. We demonstrated that methane abundance can serve as a robust metallicity indicator for these ultracool objects. We also measured a heliocentric radial velocity of -83 ± 13 km/s, inferring that WISE1810 is more likely a thick-disk member of the Milky Way.

Three SUBSTELLAR AdG team members participated in this scientific result: corresponding author MSc Jun-Yan Zhang (aka Jerry), predoctoral researcher; Dr Nikola Vitas, postdoctoral researcher and Prof Eduardo Martín, principal investigator.

Thanks to IAC for posting this important result at  IAC Website  

See the whole article at The Astrophysical Journal Letters, 984:L35 (9pp), 2025 May 1