About

Jeehey Kim is an Assistant Professor whose research encompasses the history of photography, visual culture, and film studies in East Asia. She authored the first book on the history of Korean photography in English, titled "Photography and Korea." Currently, she is working on a book project called "Photography and Death: Funerary Photo-Portraiture in East Asia." Her scholarly work also includes articles on vernacular photographic practices, documentary films, and visual culture related to the Cold War and gender politics in East Asia. As a curator, Kim has organized exhibitions such as “Pyongyang Bookstore” at the Seoul Metropolitan Library, which showcased North Korean artists of the 1950s and ’60s. She earned her doctorate at the Graduate Center, City University of New York, with a dissertation focused on funerary portrait photography in East Asia, and she was a postdoctoral fellow at the University of Chicago.

Research topics

• Physics
• Astronomy
• Astrophysics

Selected publications

• Atmospheric parameters and chemical abundances of young stars with APOGEE – I. Orion star-forming region

  Monthly Notices of the Royal Astronomical Society · 2025-09-01

  articleOpen access

  ABSTRACT We derive atmospheric parameters and chemical abundances in young G-, K-, and M-type stars (temperatures between 6500 and 3100 K) using infrared APOGEE-2 spectra. Atmospheric parameters were determined for 548 young stars in the Orion complex (Orion A, B, OB1, and $\lambda$ Ori) using the tonalli code. For 340 slow rotators ($v\sin i$ $\le$ 30 km s$^{-1}$), we derived C, Mg, Si, K, Ti, and Fe abundances using 19 atomic lines, MARCS model atmospheres, and bacchus. To mitigate the impact of circumstellar material, we excluded stars with infrared excess identified via 2MASS and WISE photometry. We find subsolar [X/H] abundance ratios, consistent across elements and among all four groups, suggesting a chemically homogeneous Orion complex. We computed [$\alpha$/Fe] from [Mg/Fe], [Si/Fe], and [Ti/Fe], obtaining a median of $-0.14 \pm 0.04$, about 0.10 dex lower than the value for nearby main-sequence stars ($-0.04 \pm 0.04$) at similar [Fe/H]. This result aligns with predictions from Galactic chemical evolution models. Furthermore, the median [C/H] abundance we derived for Orion agrees with previous estimations based on the analysis of the ionized gas of the Orion nebula. This work sets the stage for extending the analysis to stars with circumstellar material and higher rotational velocities, which will not only improve our understanding of Orion, but also provide critical insight into the formation and evolution of young stars, as well as the chemical evolution of the Milky Way.

  PublisherOA PDFDOI

• Long-term X-Ray Variability on the Benchmark YSO HL Tau

  The Astronomical Journal · 2025-02-27 · 1 citations

  articleOpen access

  Abstract HL Tau is one of the most well-studied Class I young stellar objects (YSOs), including frequent observations at near- and mid-infrared, (sub)millimeter, and X-ray wavelengths. We present the results of an X-ray variability monitoring campaign with XMM-Newton in 2020 and X-ray grating spectroscopy from Chandra/HETGS in 2018. We find that the X-ray spectrum of HL Tau is consistently hot (with characteristic plasma temperatures T ≳ 30 MK) over 31 epochs spanning 20 yr, which is consistent in temperature with most Class I YSOs. The high-resolution HETG spectrum indicates the presence of some cooler plasma. We characterize the variability of the star across the 31 observations and find a subset of observations with significant variability on a ∼21-day timescale in the observed count rate and flux. We discuss the possible origins of this variability and identify further observations that would better constrain the nature of the changes.

  PublisherDOI

• ABYSS. III. Observing Accretion Activity in Young Stars Through Empirical Veiling Measurements

  The Astronomical Journal · 2025-07-14 · 1 citations

  articleOpen accessCorresponding

  Abstract Stellar accretion plays an important role in the early stages of stellar evolution, particularly in Classical T Tauri Stars (CTTSs). Accretion of a CTTS can be related to different physical parameters such as effective temperature ( T eff ), age, abundance of hydrogen, etc. We can infer how accretion works by examining it across different wavelength regions. Accretion can be traced using veiling, a parameter that measures how excess emission from accretion affects the photospheric spectrum of CTTS. In this study, we selected a sample of CTTSs, Weak-line T Tauri Stars, and field stars, observed as a part of the SDSS-V Milky Way Mapper using the Baryonic Oscillation Spectroscopic Survey spectrograph. We measured veiling for CTTSs through comparing them to theoretical spectra. Next, we assessed the effect of veiling on different stellar properties, including wavelength, H α emission, effective temperature, and age. We investigated how veiling changes with these parameters and what the physical reasons behind the changes can be. Finally, we evaluated how our findings align with existing accretion shock models. This study highlights veiling as a critical diagnostic tool for understanding accretion in young stars.

  PublisherDOI

• The observable impact of runaway OB stars on protoplanetary discs

  ArXiv.org · 2025-05-12

  preprintOpen access

  UV radiation from OB stars can drive ``external'' photoevaporative winds from discs in clusters, that have been shown to be important for disc evolution and planet formation. However, cluster dynamics can complicate the interpretation of this process. A significant fraction of OB stars are runaways, propagating at high velocity which might dominate over the wider cluster dynamics in setting the time variation of the UV field in part of the cluster. We explore the impact of a runaway OB star on discs and the observational impact that may have. We find that discs exposed to even short periods of strong irradiation are significantly truncated, and only rebound slightly following the ``flyby'' of the UV source. This is predicted to leave an observable imprint on a disc population, with those downstream of the OB star vector being more massive and extended than those upstream. Because external photoevaporation acts quickly, this imprint is less susceptible to being washed out by cluster dynamics for faster runaway OB stars. The Gaia proper motion vector of the B star 42 Ori in NGC 1977 is transverse to the low mass stellar population and so may make a good region to search for this signature in resolved disc observations.

  PublisherOA PDFDOI

• The past, present and future of observations of externally irradiated disks

  ArXiv.org · 2025-02-17 · 2 citations

  preprintOpen access

  Recent years have seen a surge of interest in the community studying the effect of ultraviolet radiation environment, predominantly set by OB stars, on protoplanetary disc evolution and planet formation. This is important because a significant fraction of planetary systems, potentially including our own, formed in close proximity to OB stars. This is a rapidly developing field, with a broad range of observations across many regions recently obtained or recently scheduled. In this paper, stimulated by a series of workshops on the topic, we take stock of the current and upcoming observations. We discuss how the community can build on this recent success with future observations to make progress in answering the big questions of the field, with the broad goal of disentangling how external photoevaporation contributes to shaping the observed (exo)planet population. Both existing and future instruments offer numerous opportunities to make progress towards this goal.

  PublisherOA PDFDOI

• Runaway origins of a disc mass gradient in σ Orionis

  Monthly Notices of the Royal Astronomical Society Letters · 2025-09-16 · 3 citations

  articleOpen accessSenior author

  ABSTRACT Radiation from massive stars is known to significantly affect the evolution of protoplanetary discs around surrounding stars by driving ‘external’ photoevaporative winds. Typically most studies assume that the massive stars driving these winds are comoving with their associated clusters. However, it is also known that massive stars can be runaways, after being violently ejected from their birth environment through interactions with other massive stars. In this letter, we show that the well studied system $\sigma ~{\rm Ori~AB}$ is actually a runaway system, only now passing through $\sigma ~{\rm Orionis}$. There are multiple observable features that indicate this is the case, including significantly larger proper motions for $\sigma ~{\rm Orionis}$ than the surrounding stars, an infrared arc of ionizing gas along the predicted velocity vector, and a disparity in protoplanetary disc masses across $\sigma ~{\rm Orionis}$. We finally use protoplanetary disc evolution models to explain the observed disparity in disc masses, showing that those discs downstream of $\sigma ~{\rm Ori~AB}$, i.e. those yet to encounter it, have larger masses than those upstream, consistent with observations. Overall, our work highlights the importance of understanding the dynamical history of star forming regions, since the time varying UV fields provided by runway stars results in a complex history for the evolution of the protoplanetary discs.

  PublisherOA PDFDOI

• ABYSS III: Observing accretion activity in young stars through empirical veiling measurements

  ArXiv.org · 2025-06-11

  preprintOpen access

  Stellar accretion plays an important role in the early stages of stellar evolution, particularly in Classical T Tauri Stars (CTTSs). Accretion of a CTTS can be related to different physical parameters such as effective temperature (T$_{\text{eff}}$), age, abundance of hydrogen, etc. We can infer how accretion works by examining it across different wavelength regions. Accretion can be traced using veiling, a parameter that measures how excess emission from accretion affects the photospheric spectrum of CTTS. In this study, we selected a sample of CTTSs, Weak-line T Tauri Stars (WTTSs), and field stars, observed as a part of the SDSS-V Milky Way Mapper using the BOSS spectrograph. We measured veiling for CTTSs through comparing them to theoretical spectra. Next, we assessed the effect of veiling on different stellar properties, including wavelength, H$α$ emission, effective temperature, and age. We investigated how veiling changes with these parameters and what the physical reasons behind the changes can be. Finally, we evaluated how our findings align with existing accretion shock models. This study highlights veiling as a critical diagnostic tool for understanding accretion in young stars.

  PublisherOA PDFDOI

• The past, present and future of observations of externally irradiated disks

  The Open Journal of Astrophysics · 2025-05-02 · 9 citations

  articleOpen access

  Recent years have seen a surge of interest in the community studying the effect of ultraviolet radiation environment, predominantly set by OB stars, on protoplanetary disc evolution and planet formation. This is important because a significant fraction of planetary systems, potentially including our own, formed in close proximity to OB stars. This is a rapidly developing field, with a broad range of observations across many regions recently obtained or recently scheduled. In this paper, stimulated by a series of workshops on the topic, we take stock of the current and upcoming observations. We discuss how the community can build on this recent success with future observations to make progress in answering the big questions of the field, with the broad goal of disentangling how external photoevaporation contributes to shaping the observed (exo)planet population. Both existing and future instruments offer numerous opportunities to make progress towards this goal.

  PublisherDOI

• The observable impact of runaway OB stars on protoplanetary discs

  Monthly Notices of the Royal Astronomical Society · 2025-05-14 · 5 citations

  articleOpen access

  ABSTRACT Ultraviolet (UV) radiation from OB stars can drive ‘external’ photoevaporative winds from discs in clusters, that have been shown to be important for disc evolution and planet formation. However, cluster dynamics can complicate the interpretation of this process. A significant fraction of OB stars are runaways, propagating at high velocity which might dominate over the wider cluster dynamics in setting the time variation of the UV field in part of the cluster. We explore the impact of a runaway OB star on discs and the observational impact that may have. We find that discs exposed to even short periods of strong irradiation are significantly truncated, and only rebound slightly following the ‘flyby’ of the UV source. This is predicted to leave an observable imprint on a disc population, with those downstream of the OB star vector being more massive and extended than those upstream. Because external photoevaporation acts quickly, this imprint is less susceptible to being washed out by cluster dynamics for faster runaway OB stars. The Gaia proper motion vector of the B star 42 Ori in NGC 1977 is transverse to the low mass stellar population and so may make a good region to search for this signature in resolved disc observations.

  PublisherOA PDFDOI

• Long-Term X-ray Variability on the Benchmark YSO HL Tau

  ArXiv.org · 2025-02-11

  preprintOpen access

  HL Tau is one of the most well-studied Class I young stellar objects, including frequent observations at near- and mid-infrared, (sub-) millimeter, and X-ray wavelengths. We present the results of an X-ray variability monitoring campaign with XMM-Newton in 2020 and X-ray gratings spectroscopy from Chandra/HETGS in 2018. We find that the X-ray spectrum of HL Tau is consistently hot (with characteristic plasma temperatures $T \gtrsim 30$ MK) over 31 epochs spanning 20 years, which is consistent in temperature with most Class I YSOs. The high-resolution HETG spectrum indicates the presence of some cooler plasma. We characterize the variability of the star across the 31 observations and find a subset of observations with significant variability on a $\sim$21-day timescale in the observed count rate and flux. We discuss the possible origins of this variability, and identify further observations that would better constrain the nature of the changes.

  PublisherOA PDFDOI

Recent grants

• Triggered Star Forming Regions: Cradles of Forming Solar Systems?

  NSF · $312k · 2009–2013

Frequent coauthors

• Min Fang

  28 shared

• Ilaria Pascucci

  University of Arizona

  24 shared

• C. Román-Zúñiga

  21 shared

• Guy S. Stringfellow

  Laboratory for Atmospheric and Space Physics

  21 shared

• Marina Kounkel

  University of North Florida

  19 shared

• Keivan G. Stassun

  Vanderbilt University

  18 shared

• Jesús Hernández

  17 shared

• S. J. Wolk

  Center for Astrophysics Harvard & Smithsonian

  16 shared