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Jacobus Van Loon's Outputs (209)

X-Shooting ULLYSES: Massive Stars at Low Metallicity X. Physical Parameters and Feedback of Massive Stars in the LMC N11 B Star-Forming Region (2025)
Journal Article
Gómez-González, V., Oskinova, L., Hamann, W. R., Todt, H., Pauli, D., Reyero Serantes, S., Bernini-Peron, M., Sander, A., Ramachandran, V., Vink, J., Crowther, P., Berlanas, S., ud-Doula, A., Gormaz-Matamala, A., Kehrig, C., Kuiper, R., Leitherer, C., Mahy, L., McLeod, A., Mehner, A., …Wofford, A. (2025). X-Shooting ULLYSES: Massive Stars at Low Metallicity X. Physical Parameters and Feedback of Massive Stars in the LMC N11 B Star-Forming Region. Astronomy and Astrophysics, 695, 18. https://doi.org/10.1051/0004-6361/202451366

Massive stars drive the ionization and mechanical feedback within young star-forming regions. The Large Magellanic Cloud (LMC) is an ideal galaxy for studying individual massive stars and quantifying their feedback contribution to the environment. We... Read More about X-Shooting ULLYSES: Massive Stars at Low Metallicity X. Physical Parameters and Feedback of Massive Stars in the LMC N11 B Star-Forming Region.

Equatorial Enhancement in the Dustiest OH/IR Stars in the Galactic Bulge (2025)
Journal Article
Goldman, S. R., van Loon, J. T., Jones, O. C., Blommaert, J. A. D. L., & Groenewegen, M. A. T. (2025). Equatorial Enhancement in the Dustiest OH/IR Stars in the Galactic Bulge. Astrophysical Journal, 980(2), 191. https://doi.org/10.3847/1538-4357/ada6ad

We have detected the 10 μm silicate feature and the 11.3 μm crystalline forsterite feature in absorption in 21 oxygen-rich asymptotic giant branch stars in the Galactic bulge. The depths of the 10 μm feature indicate highly obscured circumstellar env... Read More about Equatorial Enhancement in the Dustiest OH/IR Stars in the Galactic Bulge.

Binarity at Low Metallicity (BLOeM) -- Multiplicity properties of Oe and Be stars (2025)
Preprint / Working Paper
Bodensteiner, J., Shenar, T., Sana, H., Britavskiy, N., Crowther, P., Langer, N., Lennon, D., Mahy, L., Patrick, L., Villaseñor, J., Abdul-Masih, M., Bowman, D., de Koter, A., de Mink, S., Deshmukh, K., Fabry, M., Gilkis, A., Götberg, Y., Holgado, G., Izzard, R., …-T. Xu, X. Binarity at Low Metallicity (BLOeM) -- Multiplicity properties of Oe and Be stars

Binarity at LOw Metallicity (BLOeM): The multiplicity properties and evolution of BAF-type supergiants (2025)
Preprint / Working Paper
Patrick, L., Lennon, D., Najarro, F., Shenar, T., Bodensteiner, J., Sana, H., Crowther, P., Britavskiy, N., Langer, N., Schootemeijer, A., Evans, C., Mahy, L., Götberg, Y., de Mink, S., Schneider, F., O'Grady, A., Villaseñor, J., Bernini-Peron, M., Bowman, D., de Koter, A., …Wang, C. Binarity at LOw Metallicity (BLOeM): The multiplicity properties and evolution of BAF-type supergiants

Multi-phase HI clouds in the Small Magellanic Cloud halo (2025)
Journal Article
Buckland-Willis, F., Miville-Deschênes, M. A., Marchal, A., Dawson, J. R., Dénes, H., Di Teodoro, E. M., Dickey, J. M., Gibson, S. J., Kemp, I. P., Lynn, C., Ma, Y. K., McClure-Griffiths, N. M., Murray, C. E., Pingel, N. M., Stanimirović, S., & Van Loon, J. T. (2025). Multi-phase HI clouds in the Small Magellanic Cloud halo. Astronomy & Astrophysics, 693, Article A239. https://doi.org/10.1051/0004-6361/202452645

Context. The Galactic ASKAP collaboration (GASKAP) is undertaking an HI emission survey of the 21cm line to map the Magellanic system and the Galactic plane with the Australian Square Kilometre Array Pathfinder (ASKAP). One of the first areas observe... Read More about Multi-phase HI clouds in the Small Magellanic Cloud halo.

The EDIBLES Survey IX: Simulations of the λ6614 DIB Profile Variations: A Surprising Connection with CH+ (2025)
Journal Article
Bhatt, C., Cami, J., Sarre, P. J., Linnartz, H., Cox, N. L. J., Farhang, A., Smoker, J., MacIsaac, H., Fan, H., Ebenbichler, A., Khandelwal, H., Romanec, A., Elyajouri, M., Ehrenfreund, P., Foing, B. H., Monreal-Ibero, A., Barco, G. M., & van Loon, J. T. (in press). The EDIBLES Survey IX: Simulations of the λ6614 DIB Profile Variations: A Surprising Connection with CH+. ACS Earth and Space Chemistry, 1-14. https://doi.org/10.1021/acsearthspacechem.4c00238

The VMC Survey – LI. Classifying extragalactic sources using a probabilistic random forest supervised machine learning algorithm (2025)
Journal Article
Pennock, C. M., van Loon, J. T., Cioni, M.-R. L., Maitra, C., Oliveira, J. M., Craig, J. E. M., Ivanov, V. D., Aird, J., Anih, J. O., Cross, N. J. G., Dresbach, F., de Grijs, R., & Groenewegen, M. A. T. (2025). The VMC Survey – LI. Classifying extragalactic sources using a probabilistic random forest supervised machine learning algorithm. Monthly Notices of the Royal Astronomical Society, 537(2), 1028-1055. https://doi.org/10.1093/mnras/staf080

We used a supervised machine learning algorithm (probabilistic random forest) to classify ∼130 million sources in the VISTA Survey of the Magellanic Clouds (VMC). We used multi-wavelength photometry from optical to far-infrared as features to be trai... Read More about The VMC Survey – LI. Classifying extragalactic sources using a probabilistic random forest supervised machine learning algorithm.

Considerations with stacking absorption spectra: cold H i gas in cirrus region of the Milky Way (2025)
Journal Article
Lynn, C., Marchal, A., McClure-Griffiths, N. M., Miville-Deschênes, M.-A., Murray, C. E., Nguyen, H., Dempsey, J., Teodoro, E. D., van Loon, J. T., Dickey, J. M., Lee, M.-Y., Joncas, G., Ma, Y. K., Pingel, N. M., Stanimirović, S., Kemp, I., Gibson, S., & Dénes, H. (2025). Considerations with stacking absorption spectra: cold H i gas in cirrus region of the Milky Way. Monthly Notices of the Royal Astronomical Society, 536(4), 3538-3553. https://doi.org/10.1093/mnras/stae2818

We use the Milky Way neutral hydrogen (H i) absorption and emission spectra from the Galactic Australian Square Kilometre Array Pathfinder (GASKAP) Phase II Pilot survey along with toy models to investigate the effects of stacking multicomponent spec... Read More about Considerations with stacking absorption spectra: cold H i gas in cirrus region of the Milky Way.

Star Formation History of the Local Group Dwarf Irregular Galaxy, NGC 6822 (2024)
Journal Article
Khatamsaz, F., Abdollahi, M., Abdollahi, H., Javadi, A., & van Loon, J. T. (in press). Star Formation History of the Local Group Dwarf Irregular Galaxy, NGC 6822. Communications of the Byurakan Astrophysical Observatory, 71(2), 394-397. https://doi.org/10.52526/25792776-24.71.2-394

NGC 6822 is an isolated dwarf irregular galaxy in the local group at a distance of ∼ 490 kpc. In this paper, we present the star formation history (SFH) within a field with a radius of ∼ 3 kpc, beyond the optical body of the galaxy ( ∼ 1.2 kpc). We u... Read More about Star Formation History of the Local Group Dwarf Irregular Galaxy, NGC 6822.

Machine Learning Classification of Young Stellar Objects and Evolved Stars in the Magellanic Clouds Using the Probabilistic Random Forest Classifier (2024)
Journal Article
Ghaziasgar, S., Abdollahi, M., Javadi, A., van Loon, J. T., McDonald, I., Oliveira, J., & Khosroshahi, H. G. (in press). Machine Learning Classification of Young Stellar Objects and Evolved Stars in the Magellanic Clouds Using the Probabilistic Random Forest Classifier. Communications of the Byurakan Astrophysical Observatory, 71(2), 377-382. https://doi.org/10.52526/25792776-24.71.2-377

The Magellanic Clouds (MCs) are excellent locations to study stellar dust emission and its contribution to galaxy evolution. Through spectral and photometric classification, MCs can serve as a unique environment for studying stellar evolution and gal... Read More about Machine Learning Classification of Young Stellar Objects and Evolved Stars in the Magellanic Clouds Using the Probabilistic Random Forest Classifier.

Deciphering Galactic Halos: A Detailed Review of Star Formation in NGC 5128 (Cen A) (2024)
Journal Article
Abdollahi, M., Aghdam, S. T., Javadi, A., Hashemi, S. A., van Loon, J. T., Khosroshahi, H., Hamedani Golshan, R., Saremi, E., & Saberi, M. (in press). Deciphering Galactic Halos: A Detailed Review of Star Formation in NGC 5128 (Cen A). Communications of the Byurakan Astrophysical Observatory, 71(2), 345-350. https://doi.org/10.52526/25792776-24.71.2-345

NGC 5128 (Centaurus A), the closest giant elliptical galaxy outside the Local Group to the Milky Way, is one of the brightest extragalactic radio sources. It is distinguished by a prominent dust lane and powerful jets, driven by a supermassive black... Read More about Deciphering Galactic Halos: A Detailed Review of Star Formation in NGC 5128 (Cen A).

A Deep Dive into Stellar Populations in M33’s Central Region: Near-Infrared Observations and Analysis (2024)
Journal Article
Alizadeh, M., Javadi, A., van Loon, J. T., Abedini, Y., Abdollahi, H., & Seifipour, S. (in press). A Deep Dive into Stellar Populations in M33’s Central Region: Near-Infrared Observations and Analysis. Communications of the Byurakan Astrophysical Observatory, 71(2), 389-393. https://doi.org/10.52526/25792776-24.71.2-389

Data collection was conducted using three cameras on the UK Infrared Telescope (UKIRT) from 2003 to 2007. Throughout three nights in August 2005, the UKIRT Fast-Track Imager (UFTI) made K-band observations. The J and H bands Wide Field Camera (WFCAM)... Read More about A Deep Dive into Stellar Populations in M33’s Central Region: Near-Infrared Observations and Analysis.

Detection of the Long Period Variable Stars of And II Dwarf Satellite galaxy (2024)
Journal Article
Abdollahi, H., Javadi, A., van Loon, J. T., McDonald, I., Abdollahi, M., Saremi, E., Khosroshahi, H. G., & Mahani, H. (in press). Detection of the Long Period Variable Stars of And II Dwarf Satellite galaxy. Communications of the Byurakan Astrophysical Observatory, 71(2), 383-388. https://doi.org/10.52526/25792776-24.71.2-383

We conducted an extensive study of the spheroidal dwarf satellite galaxies around the Andromeda galaxy to produce an extensive catalog of LPV stars. The optical monitoring project consists of 55 dwarf galaxies and four globular clusters that are memb... Read More about Detection of the Long Period Variable Stars of And II Dwarf Satellite galaxy.

X-Shooting ULLYSES: Massive stars at low metallicity: VI. Atmosphere and mass-loss properties of O-type giants in the Small Magellanic Cloud (2024)
Journal Article
Backs, F., Brands, S. A., de Koter, A., Kaper, L., Vink, J. S., Puls, J., Sundqvist, J., Tramper, F., Sana, H., Bernini-Peron, M., Bestenlehner, J. M., Crowther, P. A., Hawcroft, C., Ignace, R., Kuiper, R., van Loon, J. T., Mahy, L., Marcolino, W., Najarro, F., Oskinova, L. M., …Verhamme, O. (2024). X-Shooting ULLYSES: Massive stars at low metallicity: VI. Atmosphere and mass-loss properties of O-type giants in the Small Magellanic Cloud. Astronomy & Astrophysics, 692(December 2024), 1-24. https://doi.org/10.1051/0004-6361/202451893

Context. Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. To probe its... Read More about X-Shooting ULLYSES: Massive stars at low metallicity: VI. Atmosphere and mass-loss properties of O-type giants in the Small Magellanic Cloud.

X-Shooting ULLYSES: Massive Stars at low metallicity: IX. Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud (2024)
Journal Article
Verhamme, O., Sundqvist, J., de Koter, A., Sana, H., Backs, F., Brands, S. A., Najarro, F., Puls, J., Vink, J. S., Crowther, P. A., Kubátová, B., Sander, A. A. C., Bernini-Peron, M., Kuiper, R., Prinja, R. K., Schillemans, P., Shenar, T., van Loon, J. T., & XShootu collaboration. (2024). X-Shooting ULLYSES: Massive Stars at low metallicity: IX. Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud. Astronomy & Astrophysics, 692(December 2024), 1-24. https://doi.org/10.1051/0004-6361/202451169

Context. Current implementations of mass loss for hot, massive stars in stellar evolution models usually include a sharp increase in mass loss when blue supergiants become cooler than Teff ∼ 20 − 22 kK. Such a drastic mass-loss jump has traditionally... Read More about X-Shooting ULLYSES: Massive Stars at low metallicity: IX. Empirical constraints on mass-loss rates and clumping parameters for OB supergiants in the Large Magellanic Cloud.

Processing of GASKAP-Hi pilot survey data using a commercial supercomputer (2024)
Journal Article
Kemp, I., Pingel, N., Worth, R., Wake, J., Mitchell, D., Midgely, S., Tingay, S., Dempsey, J., Dénes, H., Dickey, J., Gibson, S., Jameson, K., Lynn, C., Ma, Y., Marchal, A., McClure-Griffiths, N., Stanimirović, S., & van Loon, J. T. (2025). Processing of GASKAP-Hi pilot survey data using a commercial supercomputer. Astronomy and Computing, 51, Article 100901. https://doi.org/10.1016/j.ascom.2024.100901

Modern radio telescopes generate large amounts of data, with the next generation Very Large Array (ngVLA) and the Square Kilometre Array (SKA) expected to feed up to 292 GB of visibilities per second to the science data processor (SDP). However, the... Read More about Processing of GASKAP-Hi pilot survey data using a commercial supercomputer.

Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud (2024)
Journal Article
Ohnaka, K., Hofmann, K.-H., Weigelt, G., van Loon, J. T., Schertl, D., & Goldman, S. R. (2024). Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud. Astronomy & Astrophysics, 691, Article L15. https://doi.org/10.1051/0004-6361/202451820

Context. Significant mass loss in the red supergiant (RSG) phase has great influence on the evolution of massive stars and their final fate as supernovae.

Aims. We present near-infrared interferometric imaging of the circumstellar environment of t... Read More about Imaging the innermost circumstellar environment of the red supergiant WOH G64 in the Large Magellanic Cloud.

Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey of massive stars in the SMC (2024)
Journal Article
Shenar, T., Bodensteiner, J., Sana, H., Crowther, P. A., Lennon, D. J., Abdul-Masih, M., Almeida, L. A., Backs, F., Berlanas, S. R., Bernini-Peron, M., Bestenlehner, J. M., Bowman, D. M., Bronner, V. A., Britavskiy, N., de Koter, A., de Mink, S. E., Deshmukh, K., Evans, C. J., Fabry, M., Gieles, M., …Willcox, R. (2024). Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey of massive stars in the SMC. Astronomy & Astrophysics, 690, 22. https://doi.org/10.1051/0004-6361/202451586

Surveys in the Milky Way and Large Magellanic Cloud have revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, and therefore in c... Read More about Binarity at LOw Metallicity (BLOeM): A spectroscopic VLT monitoring survey of massive stars in the SMC.