Zobrazeno 1 - 10
of 539
pro vyhledávání: '"Helmer, H"'
Autor:
Viswanathan, Akshara, Starkenburg, Else, Koppelman, Helmer H., Helmi, Amina, Balbinot, Eduardo, Esselink, Anna F.
The Milky Way halo is one of the few galactic haloes that provides a unique insight into galaxy formation by resolved stellar populations. Here, we present a catalogue of $\sim$47 million halo stars selected independent of parallax and line-of-sight
Externí odkaz:
http://arxiv.org/abs/2302.00053
Autor:
Matsuno, Tadafumi, Dodd, Emma, Koppelman, Helmer H., Helmi, Amina, Ishigaki, Miho N., Aoki, Wako, Zhao, Jingkun, Yuan, Zhen, Hattori, Kohei
Publikováno v:
A&A 665, A46 (2022)
Context: The Helmi streams are a kinematic substructure whose progenitor is likely a dwarf galaxy. Although 20 years have passed since their discovery, it is still unclear whether their members are chemically distinguishable from other halo stars in
Externí odkaz:
http://arxiv.org/abs/2203.11808
Autor:
Ruiz-Lara, Tomás, Matsuno, Tadafumi, Lövdal, S. Sofie, Helmi, Amina, Dodd, Emma, Koppelman, Helmer H.
Publikováno v:
A&A 665, A58 (2022)
In L\"ovdal et al, we presented a data-driven method for clustering in Integrals of Motion space and applied it to a large sample of nearby halo stars with 6D phase-space information. We identified a large number of clusters, many of which could tent
Externí odkaz:
http://arxiv.org/abs/2201.02405
Autor:
Lövdal, S. Sofie, Ruiz-Lara, Tomás, Koppelman, Helmer H., Matsuno, Tadafumi, Dodd, Emma, Helmi, Amina
Publikováno v:
A&A 665, A57 (2022)
Aims: Develop a data-driven and statistically based method for finding such clumps in Integrals of Motion space for nearby halo stars and evaluating their significance robustly. Methods: We use data from Gaia EDR3 extended with radial velocities from
Externí odkaz:
http://arxiv.org/abs/2201.02404
Autor:
Matsuno, Tadafumi, Koppelman, Helmer H., Helmi, Amina, Aoki, Wako, Ishigaki, Miho N., Suda, Takuma, Yuan, Zhen, Hattori, Kohei
Publikováno v:
A&A 661, A103 (2022)
Context: Sequoia is a retrograde kinematic substructure in the nearby Galactic halo, whose properties are a matter of debate. For example, previous studies do not necessarily agree on the chemical abundances of Sequoia stars, which are important for
Externí odkaz:
http://arxiv.org/abs/2111.15423
Autor:
Borre, Camilla C., Børsen-Koch, Víctor Aguirre, Helmi, Amina, Koppelman, Helmer H., Nielsen, Martin B., Rørsted, Jakob L., Stello, Dennis, Stokholm, Amalie, Winther, Mark L., Davies, Guy R., Hon, Marc, Kruijssen, J. M. Diederik, Laporte, Chervin, Reyes, Claudia, Yu, Jie
The Milky Way was shaped by the mergers with several galaxies in the past. We search for remnant stars that were born in these foreign galaxies and assess their ages in an effort to put upper limits on the merger times and thereby better understand t
Externí odkaz:
http://arxiv.org/abs/2111.01669
Publikováno v:
A&A 659, A61 (2022)
The local stellar halo of the Milky Way contains the debris from several past accretion events. Here we study in detail the structure and properties of nearby debris associated with the Helmi streams, originally identified as an overdensity in integr
Externí odkaz:
http://arxiv.org/abs/2105.09957
Autor:
Koppelman, Helmer H., Helmi, Amina
Publikováno v:
A&A 649, A55 (2021)
When a subhalo interacts with a cold stellar stream it perturbs its otherwise nearly smooth distribution of stars, and this leads to the creation of a gap. The properties of such gaps depend on the parameters of the interaction. Their characterisatio
Externí odkaz:
http://arxiv.org/abs/2011.11684
Frequencies, chaos and resonances: a study of orbital parameters of nearby thick disc and halo stars
Publikováno v:
A&A 647, A37 (2021)
We study the distribution of nearby thick disc and halo stars in subspaces defined by their characteristic orbital parameters. Our aim is to establish the origin of the structure reported in particular, in the $R_{\rm max}-z_{\rm max}$ space. To this
Externí odkaz:
http://arxiv.org/abs/2009.04849
Autor:
Reino, Stella, Rossi, Elena M., Sanderson, Robyn E., Sellentin, Elena, Helmi, Amina, Koppelman, Helmer H., Sharma, Sanjib
Stream stars removed by tides from their progenitor satellite galaxy or globular cluster act as a group of test particles on neighboring orbits, probing the gravitational field of the Milky Way. While constraints from individual streams have been sho
Externí odkaz:
http://arxiv.org/abs/2007.00356