Johanna Hartke
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jhartke.bsky.social
Johanna Hartke
@jhartke.bsky.social
300 followers 270 following 150 posts
Astronomer. Collegium Researcher at the Finnish Centre for Astronomy with ESO, University of Turku, FI. Working on galaxy halos, intra-cluster light and planetary nebulae as kinematic tracers and all things IFU. She/her.
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jhartke.bsky.social
I had a great time virtually showing first-year hight school students around @eso.org's Paranal Observatory during the @utu.fi Demo Day yesterday. With this event, we aim to inspire high school students to pursue studies in technology, natural sciences, and health sciences. 🔭👩‍🔬
Classroom at the university of Turku (without students). On the left side of is a banner of the European Southern Observatory showing UT-4 under the Milky Way and with an active laser guide star facility. The screen shows the first slide of the presentation "A virtual trip to the European Southern Observatory in Chile" with the Paranal platform and 4 unit telescopes in the background.
April 24, 2025 at 1:15 PM
jhartke.bsky.social
We find that UDG 32 is indeed part of the same dynamic structure as NGC 3314a by determining its line-of-sight velocity 🔭 8/12
Velocity distribution of galaxies in the Hydra I cluster (grey). With this figure, we illustrate that UDG 32 has a similar line-of-sight velocity as the nearby jellyfish galaxy NGC 3314A, around 3000 km/s. Adapted from Fig. 3 in Hartke et al. (2025).
January 29, 2025 at 8:13 AM
jhartke.bsky.social
Our MUSE cube was full of surprises: extended Halpha emission due to the stripped material from NGC 3314a covering a good half of the FoV, diffuse Milky Way ISM in the foreground, intra-cluster globular clusters from the Hydra I Cluster, and a background galaxy at redshift z~0.2. 🔭 7/12
This figure is a modified version of Fig. 1 in Hartke et al. (2025) and shows the filamentary structure traced by Halpha emission on top of the MUSE white light image in blue, diagonally crossing the field of view and covering about half of UDG 32, whose effective radius is denoted with a dashed ellipse. Within that ellipse, are two intra-cluster globular clusters, encircled in purple.
January 29, 2025 at 8:13 AM
jhartke.bsky.social
UDG 32 is puzzling as it lies right on top of the stripped material from the jellyfish galaxy NGC 3314A -- at least in projection. But are these two galaxies actually part of the same structure and could UDG 32 have formed from the stripped material? 🔭 6/12
Modified version of Fig. 1 in Hartke et al. (2025): three panel figure showing UDG 32 and its environment. The left panel shows a deep colour image with a rainbow colour scale from Iodice et al. (2021) taken with OmegaCAM, together with HI contours from Hess et al. (2022) in black. UDG 32 is located in the extension of the material stripped from NGC 3314a, but the HI contours that also trace the stripped material do not reach quite as far. The middle panel shows a colour image of the same field of view, with UDG 32 best described as a fuzzy orange structure in the lower-left corner. The right panel shows a zoomed-in version, with the colour image derived from our new MUSE data.
January 29, 2025 at 8:06 AM
jhartke.bsky.social
Happy Paper(s) Day to the LEWIS collaboration! LEWIS papers II (led by Dr Chiara Buttitta, postdoc at INAF in Naples) and III (led by me) are out on the arXiv today and accepted for publication in Astronomy & Astrophysics 🎉🔭👩‍🔬#ExtragalacticAstronomy 1/12
Logo of the LEWIS collaboration: cube with one side showing a rainbow visualising the wavelength axis of our data, one the image of an ultra-diffuse galaxy, and the third side a light-blue splash with the text 'LEWIS' written on top. Logo design by Enrica Iodice (INAF).
January 29, 2025 at 8:05 AM
jhartke.bsky.social
Got treated to this beautiful view before touching down in Helsinki yesterday afternoon. Even managed to catch Venus with my old phone camera 🤩
Moon and Venus seen from a plane window during the sunset.
January 5, 2025 at 3:11 PM
jhartke.bsky.social
Good morning Turku ☀️
View along Turku's Aura river from Martinsilta in the morning dawn.
December 4, 2024 at 8:02 AM
jhartke.bsky.social
Helsinki sunset from last week. #DieHellenDinge
View from the rooftop of the Helsinki Central Library Oodi towards the sunset over the Finnish parliament, Helsinki Music Centre, and Finlandia hall in the distance.
November 18, 2024 at 12:23 PM
jhartke.bsky.social
Not the "DES filters" I was looking for, thank you very much... Luckily searching for "DECam filters" proved more successful. 🔭 #MultilingualProblems #Astronomy
Screenshot of a google search of "des filters" with results "So dekliniert man Filter im Deutschen" and "Filter | Schreibweise und Deklination Substantiv"
September 9, 2024 at 11:50 AM
jhartke.bsky.social
Happy Spring from Finland. Send warm thoughts...
Yard covered in snow
April 23, 2024 at 7:19 AM
jhartke.bsky.social
Today’s observing school lesson in Asiago: yelling at clouds. 🔭
Completely clouded out Asiago observatory
February 6, 2024 at 10:13 PM
jhartke.bsky.social
Some fun with gratings and the dome of the Galileo telescope 🔭🌈
First and second order of a solar spectrum projected onto the inside of the dome of the Galileo telescope in Asiago.
February 5, 2024 at 10:15 PM
jhartke.bsky.social
Kicking off the NEON observing school on a beautiful and crisp Monday morning at Asiago Observatory 🔭👩‍🔬
Students walking up to the observatory in the sunshine. Asiago observatory with Galileo telescope
February 5, 2024 at 9:36 AM
jhartke.bsky.social
I think my biggest work achievement today will have been making it to the office without major injury. The cherry on the icing would be if I also made it back in the dark 🫣
Icy path on UTU campus.
January 23, 2024 at 8:14 AM
jhartke.bsky.social
Wrapped up my trip to what I think may be the most northern astronomy 🔭 group in the world at the University of Oulu. It was fun to travel there through the winter landscape and to chat about all things low-surface brightness.
Train in the snowy Turku station about to leave for Tampere. View from the train to Oulu showing plenty of snow. Oulu university’s Linnanmaa campus in morning twilight. Snowy park in Oulu in the sunshine.
January 21, 2024 at 10:42 AM
jhartke.bsky.social
My wishes have been heard ☀️
Antenna on the ESAC campus in front of a blue sky.
December 14, 2023 at 12:23 PM
jhartke.bsky.social
My plan to collect some vitamin D at the workshop in Spain is working out splendidly so far 🌫️
Antenna on the ESAC campus in front of a very grey sky.
December 12, 2023 at 4:01 PM
jhartke.bsky.social
Today was absolutely gorgeous. Crisp, sunny, around zero degrees. I wish every autumn day could be like this.
View down the placid Aura river in Turku that reflects the cloudless blue sky Linnankatu in Turku completely covered in leaves. In the background one can see Turku's cathedral and the Aura river.
October 29, 2023 at 4:20 PM
jhartke.bsky.social
This week the IAUS-384 on planetary nebulae is taking place in Krakow under the watchful eyes of Copernicus in the beautiful Collegium Novum of the Jagiellonian University. 🔭
Painting of Copernicus in the Aula of Collegium Novum, Krakow View up the central stairwell of Collegium Novum, with a blue banner displaying the university logo hanging from the top floor balcony. IAU banner advertising symposium 384 on planetary nebulae
September 5, 2023 at 1:49 PM
jhartke.bsky.social
One of my favourite dioramas created by her with the book cover of Comet in Moominland in the background.
Diorama of the observatory on the mountaintop.
August 9, 2023 at 9:29 AM
jhartke.bsky.social
Gotta love Finnish libraries. Always a friendly space and a great place to stop for book and coffee.
Cafe inside the Tampere main library Interior of the Tampere main library.
August 6, 2023 at 9:13 AM
jhartke.bsky.social
Not sure whether many members of the #AlumNode community are on this platform yet, but tomorrow I'll be talking about academic posters in the coffee break. More information here: https://alumnode.org/events/33/
August 2, 2023 at 3:47 PM