Skip to Content
Version 13.3 by Thomas Hackman on 2024/03/05 13:36
Show last authors
1 The University of Helsinki astrophysics research group focuses on observations of stellar magnetic activity and its relation to exoplanets. The goal is to use these observations for a better general understanding of the magnetic activity of solar type stars, and in particular the Sun's activity. We also investigate the influence of a stars activity on the detectability of exoplanets. We use the following observations:
2
3 * High resolution spectroscopy from e.g. the Nordic Optical Telescope (NOT) and telescopes of the European Southern Observatory (ESO)
4 * Spectropolarimetry from e.g. the NOT and ESO
5 * Ground based photometry from e.g. Automated Photometric Telescopes
6 * Space based high precision photometry from e.g. the Transiting Exoplanet Survey Satellite
7 * Ground-based Ca II H&K monitoring surveys
8 * Radiocarbon measurements from tree rings
9
10 Methods we are using include Doppler imaging, Zeeman-Doppler imaging (ZDI) and time series analysis. Radiocarbon measurements are used to detect historical solar energetic particle events.
11
12 The research team consists of:
13
14 * Thomas Hackman, PhD, University researcher
15 * András Haris-Kiss, MSc, Doctoral researcher
16 * Jyri Lehtinen, PhD, Post-doc researcher (Finnish Centre for Astronomy with ESO)
17 * Aino Luttinen, BSc student
18 * Nora Routamo, BSc, Master student
19 * Mikko Tuomi, PhD, University researcher
20 * Teemu Willamo, PhD
21 * Joonas Uusitalo, MSc, Doctoral researcher (Laboratory of Chronology, University of Helsinki)
22
23 In addtion three undergraduate students are members of the group.
24
25 The group has extensive cooperation with a large number of national and international research institutes, e.g.: Aalto University (Maarit Korpi-Lagg), University of Oulu (Eija Tanskanen), Uppsala University (Oleg Kochukhov), Max Planck Institute for Solar System Research (Jörn Warnecke), AIP Potsdam (Ilya Ilyin), Konkoly Thege Miklós Astronomical Institute (Zsolt Kővári), Tennessee State University
26
27 **Recent presentations at seminars and scientific conferences**
28
29 Posters at the 21st Cambridge Workshop: Cool Stars, Stellar Systems and the Sun in Toulouse 4-9 July, 2022:
30
31 * V889 Her: abrupt changes in the magnetic field or differential rotation? [[Willamo_poster.pdf>>url:https://wiki.helsinki.fi/xwiki/bin/download/SOL/Stellar%20astrophysics%20group%20at%20University%20of%20Helsinki/SOLSTICE/WebHome/Willamo_poster.pdf?rev=1.1]]
32 * [[Investigating historical Solar eruptions>>url:https://wiki.helsinki.fi/xwiki/bin/download/SOL/Stellar%20astrophysics%20group%20at%20University%20of%20Helsinki/SOLSTICE/WebHome/Hackman_poster_CS21.pdf?rev=1.1]]
33
34 **Recent publications by team members**
35
36 Hackman, T., Kochukhov, O. , Viviani, M., Warnecke, J. , Korpi-Lagg, M.J., Lehtinen, J.J., 2024, "From convective stellar dynamo simulations to Zeeman-Doppler images", A&A 682, A156
37
38 [[https:~~/~~/www.aanda.org/articles/aa/pdf/2024/02/aa47144-23.pdf>>https://www.aanda.org/articles/aa/pdf/2024/02/aa47144-23.pdf]]
39
40 Kochukhov, O., Hackman, T., Lehtinen, J.J, 2023, Surface distribution of small-scale magnetic field on the active cool star LQ Hydrae, A&A 680, L17
41
42 [[https:~~/~~/www.aanda.org/articles/aa/pdf/2023/12/aa47930-23.pdf>>https://www.aanda.org/articles/aa/pdf/2023/12/aa47930-23.pdf]]
43
44 Lehtinen, J.J., Käpylä, M.J., Hackman, T., Kochukhov, O., Willamo, T., Marsden, S.C., Jeffers, S.V., Henry, G.W., Jetsu, L., 2022, ”Topological changes in the magnetic field of LQ Hya during an activity minimum”, A&A 660, A141
45
46 [[https:~~/~~/www.aanda.org/articles/aa/pdf/2022/04/aa36780-19.pdf>>url:https://www.aanda.org/articles/aa/pdf/2022/04/aa36780-19.pdf]]
47
48 Uusitalo, J, Arppe L., Helamaa, S. et al., 2022, "From lakes to ratios: ^^14^^C measurement process of the Finnish tree-ring research consortium", NIMPB 519, 37
49
50 [[https:~~/~~/doi.org/10.1016/j.nimb.2022.03.013>>url:https://doi.org/10.1016/j.nimb.2022.03.013]]
51
52 Uusitalo, J., Golubenko, K., Arppe, L., Brehm, N., Hackman, T., Hayakawa, H., Helama, S., Mizohata, K., Miyake, F., Mäkinen, H., Nöjd, Tanskanen, E., Tokanai, F., Rozanov, E., Wacker, L., Usoskin, Oinonen, M, 2024, "Transient Offset in 14C after the Carrington Event Recorded by Polar Tree Rings, Geophysical Research Letters, published online
53
54 [[https:~~/~~/doi.org/10.1029/2023GL106632>>https://doi.org/10.1029/2023GL106632]]
55
56 Willamo, T., 2022, "Stellar activity : starspots, magnetic fields and activity cycles", PhD thesis, University of Helsinki, Report series in Astronomy 30
57
58 [[https:~~/~~/helda.helsinki.fi/handle/10138/342285>>url:https://helda.helsinki.fi/handle/10138/342285]]
59
60 Willamo, T., Hackman, T., Lehtinen, J.J., Korpi-Lagg, M., Kochukhov, Oleg, 2022, ”V889 Her: abrupt changes in the magnetic field or differential rotation?”, OJAp 5, 10
61
62 [[https:~~/~~/arxiv.org/pdf/2203.13398v2.pdf>>url:https://arxiv.org/pdf/2203.13398v2.pdf]]
63
64 Willamo, T., Lehtinen, J.J., Hackman, T., Käpylä, M. J., Kochukhov, O., Jeffers, S.V., Korhonen, H., Marsden, S.C, 2022, ”Zeeman-Doppler imaging of five young solar-type stars”, A&A 659, A71
65
66 [[https:~~/~~/www.aanda.org/articles/aa/pdf/2022/03/aa41649-21.pdf>>url:https://www.aanda.org/articles/aa/pdf/2022/03/aa41649-21.pdf]]
67
68
69