Publications

2024

1. Scylla IV: Intrinsic Stellar Properties and Line-of-Sight Dust Extinction Measurements Towards 1.5 Million Stars in the SMC and LMC

   Christina W. Lindberg, Claire E. Murray, Petia Yanchulova Merica-Jones, and 14 more authors

   arXiv e-prints, Oct 2024

   Abs DOI Bib

   By analyzing the spectral energy distributions (SEDs) of resolved stars in nearby galaxies, we can constrain their stellar properties and line-of-sight dust extinction. From the Scylla survey, we obtain ultraviolet to near-infrared photometry from Wide Field Camera 3 onboard the Hubble Space Telescope for more than 1.5 million stars in the SMC and LMC. We use the Bayesian Extinction and Stellar Tool (BEAST) to analyze the multi-band SEDs of these sources and characterize their initial masses, ages, metallicities, distances, and line-of-sight extinction properties (e.g. Av, Rv). We apply quality cuts and perform validation simulations to construct a catalog of over 550,000 stars with high-reliability SED fits, which we use to analyze the stellar content and extinction properties of the SMC and LMC. We detect stars with masses as low as 0.6 M ⊙. BEAST stellar age distributions show a jump in observed stars around 6 Gyrs ago, which agrees with star-formation histories. Extinctions (A_V) in both galaxies follow a log-normal distribution. We compare Av with ancillary gas and dust tracers like HI, H_α, and far infrared (FIR) dust emission and find positive correlations on a field-by-field basis. We convert observed A_V to predicted dust surface densities using the Draine et. al. (2014) model and find A_V-based dust surface densities are a factor of  2.5 lower than observed FIR-based dust surface densities, a correction factor similar to other studies.

   @article{lindberg2025a,
     author = {{Lindberg}, Christina W. and {Murray}, Claire E. and {Yanchulova Merica-Jones}, Petia and {Bot}, Caroline and {Burhenne}, Clare and {Choi}, Yumi and {Clark}, Christopher J.~R. and {Cohen}, Roger E. and {Gilbert}, Karoline M. and {Goldman}, Steven R. and {Gordon}, Karl D. and {Hirschauer}, Alec S. and {McQuinn}, Kristen B.~W. and {Roman-Duval}, Julia C. and {Sandstrom}, Karin M. and {Tarantino}, Elizabeth and {Williams}, Benjamin F.},
     title = {{Scylla IV: Intrinsic Stellar Properties and Line-of-Sight Dust Extinction Measurements Towards 1.5 Million Stars in the SMC and LMC}},
     journal = {arXiv e-prints},
     keywords = {Astrophysics - Astrophysics of Galaxies},
     year = {2024},
     month = oct,
     eid = {arXiv:2410.19910},
     pages = {arXiv:2410.19910},
     doi = {10.48550/arXiv.2410.19910},
     archiveprefix = {arXiv},
     eprint = {2410.19910},
     primaryclass = {astro-ph.GA},
     adsurl = {https://ui.adsabs.harvard.edu/abs/2024arXiv241019910L},
     adsnote = {Provided by the SAO/NASA Astrophysics Data System}
   }

2. Scylla. III. The Outside-in Radial Age Gradient in the Small Magellanic Cloud and the Star Formation Histories of the Main Body, Wing, and Outer Regions

   Roger E. Cohen, Kristen B. W. McQuinn, Claire E. Murray, and 13 more authors

   \apj, Nov 2024

   DOI
3. Scylla. II. The Spatially Resolved Star Formation History of the Large Magellanic Cloud Reveals an Inverted Radial Age Gradient

   Roger E. Cohen, Kristen B. W. McQuinn, Claire E. Murray, and 11 more authors

   \apj, Nov 2024

   DOI
4. Dust around Massive Stars Is Agnostic to Galactic Environment: New Insights from PHAT/BEAST

   Christina Willecke Lindberg, Claire E. Murray, Julianne J. Dalcanton, and 2 more authors

   Astrophysical Journal, Mar 2024

   Abs DOI Bib

   Resolving the environments of massive stars is crucial for understanding their formation mechanisms and their impact on galaxy evolution. An important open question is whether massive stars found in diffuse regions outside spiral arms formed in situ or migrated there after forming in denser environments. To address this question, we use multiresolution measurements of extinction in the Andromeda galaxy (M31) to probe the interstellar medium surrounding massive stars across galactic environments. We construct a catalog of 42,107 main-sequence massive star candidates (M ≥ 8 M ⊙) using resolved stellar photometry from the Panchromatic Hubble Andromeda Treasury (PHAT) program, plus stellar and dust model fits from the Bayesian Extinction and Stellar Tool (BEAST). We quantify galactic environments by computing surrounding stellar densities of massive stars using kernel density estimation. We then compare high-resolution line-of-sight extinction estimates from the BEAST with 25 pc resolution dust maps from PHAT, measuring the total column density distribution of extinction. Our key finding is that, although the average total column density of dust increases with the density of massive stars, the average line-of-sight extinction toward massive stars remains constant across all environments. This suggests that massive stars have a uniform amount of dust in their immediate environment, regardless of their location in the galaxy. One possible explanation for these findings is that small molecular clouds are still capable of forming massive stars, even if they are not resolvable at 25 pc. These results indicate that massive stars are forming in the sparse regions of M31, as opposed to migrating there.

   @article{lindberg2024,
     author = {{Lindberg}, Christina Willecke and {Murray}, Claire E. and {Dalcanton}, Julianne J. and {Peek}, J.~E.~G. and {Gordon}, Karl D.},
     title = {{Dust around Massive Stars Is Agnostic to Galactic Environment: New Insights from PHAT/BEAST}},
     journal = {Astrophysical Journal},
     keywords = {Massive stars, Interstellar medium, Hubble Space Telescope, Interstellar dust, Stellar populations, 732, 847, 761, 836, 1622, Astrophysics - Astrophysics of Galaxies},
     year = {2024},
     month = mar,
     volume = {963},
     number = {1},
     eid = {58},
     pages = {58},
     doi = {10.3847/1538-4357/ad18cc},
     archiveprefix = {arXiv},
     eprint = {2401.10991},
     primaryclass = {astro-ph.GA},
     adsurl = {https://ui.adsabs.harvard.edu/abs/2024ApJ...963...58L},
     adsnote = {Provided by the SAO/NASA Astrophysics Data System}
   }

5. Scylla. I. A Pure-parallel, Multiwavelength Imaging Survey of the ULLYSES Fields in the LMC and SMC

   Claire E. Murray, Christina W. Lindberg, Petia Yanchulova Merica-Jones, and 17 more authors

   \apjs, Nov 2024

   DOI

2022

1. Characterizing Sparse Asteroid Light Curves with Gaussian Processes

   Christina Willecke Lindberg, Daniela Huppenkothen, R. Lynne Jones, and 11 more authors

   Astronomical Journal, Jan 2022

   Abs DOI Bib

   In the era of wide-field surveys like the Zwicky Transient Facility and the Rubin Observatory’s Legacy Survey of Space and Time, sparse photometric measurements constitute an increasing percentage of asteroid observations, particularly for asteroids newly discovered in these large surveys. Follow-up observations to supplement these sparse data may be prohibitively expensive in many cases, so to overcome these sampling limitations, we introduce a flexible model based on Gaussian processes to enable Bayesian parameter inference of asteroid time-series data. This model is designed to be flexible and extensible, and can model multiple asteroid properties such as the rotation period, light-curve amplitude, changing pulse profile, and magnitude changes due to the phase-angle evolution at the same time. Here, we focus on the inference of rotation periods. Based on both simulated light curves and real observations from the Zwicky Transient Facility, we show that the new model reliably infers rotational periods from sparsely sampled light curves and generally provides well-constrained posterior probability densities for the model parameters. We propose this framework as an intermediate method between fast but very limited-period detection algorithms and much more comprehensive but computationally expensive shape-modeling based on ray-tracing codes.

   @article{lindberg2022,
     author = {{Lindberg}, Christina Willecke and {Huppenkothen}, Daniela and {Jones}, R. Lynne and {Bolin}, Bryce T. and {Juri{\'c}}, Mario and {Golkhou}, V. Zach and {Bellm}, Eric C. and {Drake}, Andrew J. and {Graham}, Matthew J. and {Laher}, Russ R. and {Mahabal}, Ashish A. and {Masci}, Frank J. and {Riddle}, Reed and {Shin}, Kyung Min},
     title = {{Characterizing Sparse Asteroid Light Curves with Gaussian Processes}},
     journal = {Astronomical Journal},
     keywords = {72, 1930, 1900, 1916, 1955},
     year = {2022},
     month = jan,
     volume = {163},
     number = {1},
     eid = {29},
     pages = {29},
     doi = {10.3847/1538-3881/ac3079},
     adsurl = {https://ui.adsabs.harvard.edu/abs/2022AJ....163...29L},
     adsnote = {Provided by the SAO/NASA Astrophysics Data System}
   }

2018

1. QuaStar: The first unobscured view of the Milky Way’s Circumgalactic Medium

   Joshua Peek

   Nov 2018