About

Patrick M. Hartigan is a Professor of Physics and Astronomy at Rice University. His research areas include star formation, stellar jets, laboratory astrophysics, telescopes, astronomy, nebulae, and objects in the night sky. He holds a Bachelor of Science degree in Physics and Astrophysics from the University of Minnesota, obtained in 1981, and a PhD in Planetary Science from the University of Arizona, earned in 1987. His academic background and research focus are centered on understanding various phenomena in astrophysics, contributing to the scientific community's knowledge of celestial objects and processes.

Research topics

• Astronomy
• Astrophysics
• Optics
• Physics

Selected publications

• A Search for Eclipse Cycles Similar to the Hypersaros: Columbus and the Lunar Eclipse of 2025 March 14

  Research Notes of the AAS · 2025-02-07

  articleOpen access1st authorCorresponding

  Abstract The total lunar eclipse on 2025 March 14 UT occurs nearly exactly 521 yr (one Hypersaros) after a similar eclipse on 1504 March 1 UT that is renowned for its importance to the voyage of Columbus to Jamaica. Eclipses separated by a Hypersaros have similar depths, appear very close to the same location in the sky, and occur at nearly the same time of year. This paper summarizes the results from a search for analogous cycles within the Five Millennium Catalogs of Lunar and Solar Eclipses. Under the two simple constraints of similar eclipse dates relative to the vernal equinox and similar paths of the Moon through the Earth’s shadow, the most common time intervals between lunar eclipses separated by less than 1000 yr are the 521 yr Hypersaros and a 633 yr period of the Icosa-Inex-Triple-Saros. Notable cycles at longer periods occur at 1154, 1284, 1787, 1917, and 2308 yr.

  PublisherDOI

• A Search for Eclipse Cycles Similar to the Hypersaros: Columbus and the Lunar Eclipse of March 14, 2025

  ArXiv.org · 2025-02-03

  preprintOpen access1st authorCorresponding

  The total lunar eclipse on March 14, 2025 UT occurs nearly exactly 521 years (one Hypersaros) after a similar eclipse on March 1, 1504 UT that is renowned for its importance to the voyage of Columbus to Jamaica. Eclipses separated by a Hypersaros have similar depths, appear very close to the same location in the sky, and occur at nearly the same time of year. This paper summarizes the results from a search for analogous cycles within the Five Millennium Catalogs of Lunar and Solar Eclipses. Under the two simple constraints of similar eclipse dates relative to the vernal equinox and similar paths of the Moon through the Earth's shadow, the most common time intervals between lunar eclipses separated by less than 1000 years are the 521-year Hypersaros and a 633-yr period of the Icosa-Inex-Triple-Saros (IITS). Notable cycles at longer periods occur at 1154, 1284, 1787, 1917, and 2308 years.

  PublisherOA PDFDOI

• PROJECT-J: The Shocking H ₂ Outflow from HH 46

  The Astrophysical Journal · 2025-12-16 · 3 citations

  articleOpen accessCorresponding

  Abstract We analyze the H 2 emission observed in the HH 46 Class I system as part of PROtostellar JEts Cradle Tested with JWST (PROJECT-J), to investigate the origin and excitation of the warm molecular outflow. We used NIRSpec and MIRI spectral maps (1.6–27.9 μ m) to trace the structure and physical conditions of the outflow. By fitting the H 2 rotational diagrams with a multitemperature gas model, we derived key physical parameters, including temperature, extinction, column densities, and the ortho-to-para ratio. This information is combined with a detailed kinematical analysis and comparison with irradiated shock models. We find no evidence of H 2 temperature or velocity stratification from the axis to the edge of the outflow, as would be expected in MHD disk-wind models and as observed in other outflows. Instead, the observations suggest that the H 2 emission arises from shock interactions of jet bow shocks and/or wide-angle winds with the ambient medium and cavity walls. NIRSpec emission and velocity maps reveal expanding molecular shells, likely driven by the less luminous source in the binary system. We infer an accretion rate of ≲10 −9 M ⊙ yr −1 for the secondary source, approximately one order of magnitude lower than that of the primary. The H 2 emission is consistent with excitation by low-velocity (∼10 km s −1 ) J-type shocks, irradiated by an external UV field that may originate from strong dissociative shocks driven by the atomic jet. Future JWST observations will further constrain the evolution of the expanding shell and the mechanisms driving the outflow.

  PublisherDOI

• Deep DECam Survey of Carina Nebula: Unveiling YSO Short-Term Variability

  Nova Science Publishers (Nova Science Publishers, Inc.) · 2025-06-01

  otherSenior author

  We aim to study the process of accretion in Young Stellar Objects (YSOs) thanks to the release of the deepest catalogue of the Carina Nebula star-forming region (Tramuto et al., in prep.) made with Dark Energy Camera (DECam) in the 'z' band, whose survey (Hartigan et al., in prep.) has managed to retrieve time-domain data of variable sources like the YSOs in this very rich stellar nursery. The study of large samples of young star cluster members involving many different kinds of parameters is critical for understanding the evolution of accretion on an individual vs. statistical basis. In particular, using our Carina Nebula dataset, containing YSOs, we are able to retrieve information on the physical phenomena behind the different cases of short-term variability in YSOs (timescale: hours/days), most of them caused by the accretion of matter from the circumstellar disk, like bursters, dippers (due to the presence of warped disks), flares (due to magnetic reconnection). Here we discuss statistical investigation performed on the catalogue to infer its capability to discriminate YSOs in this star-forming region (SFR) and to reconstruct the pace of fast-changing flux of these sources and the physics behind them.Moreover, with the arrival of the Rubin Legacy Survey of Space and Time (LSST), there will be unprecedented opportunities to extract large catalogues of YSOs and study their distinct physical processes thanks to its deep filters and multi-band information. Using our data from DECam — a significant precursor to the Rubin LSST — as well as insights from its time-series data, we will present the most comprehensive and deep survey of the Carina Nebula SFR, so that this study will be crucial in preparation for the future Rubin LSST data (Bonito & Hartigan et al. 2018 and Bonito & Venuti et al. 2023)

  Publisher

• PDRs4All

  Astronomy and Astrophysics · 2024-05-21 · 18 citations

  articleOpen access

  Context. Mid-infrared emission features are important probes of the properties of ionized gas and hot or warm molecular gas, which are difficult to probe at other wavelengths. The Orion Bar photodissociation region (PDR) is a bright, nearby, and frequently studied target containing large amounts of gas under these conditions. Under the “PDRs4All” Early Release Science Program for JWST, a part of the Orion Bar was observed with MIRI integral field unit (IFU) spectroscopy, and these high-sensitivity IR spectroscopic images of very high angular resolution (0.2″) provide a rich observational inventory of the mid-infrared (MIR) emission lines, while resolving the H II region, the ionization front, and multiple dissociation fronts. Aims. We list, identify, and measure the most prominent gas emission lines in the Orion Bar using the new MIRI IFU data. An initial analysis summarizes the physical conditions of the gas and demonstrates the potential of these new data and future IFU observations with JWST. Methods. The MIRI IFU mosaic spatially resolves the substructure of the PDR, its footprint cutting perpendicularly across the ionization front and three dissociation fronts. We performed an up-to-date data reduction, and extracted five spectra that represent the ionized, atomic, and molecular gas layers. We identified the observed lines through a comparison with theoretical line lists derived from atomic data and simulated PDR models. The identified species and transitions are summarized in the main table of this work, with measurements of the line intensities and central wavelengths. Results. We identified around 100 lines and report an additional 18 lines that remain unidentified. The majority consists of H I recombination lines arising from the ionized gas layer bordering the PDR. The H I line ratios are well matched by emissivity coefficients from H recombination theory, but deviate by up to 10% because of contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni. We show how the Ne III /Ne II , S IV /S III , and Ar III /Ar II ratios trace the conditions in the ionized layer bordering the PDR, while Fe III /Fe II and Ni III /Ni II exhibit a different behavior, as there are significant contributions to Fe II and Ni II from the neutral PDR gas. We observe the pure-rotational H 2 lines in the vibrational ground state from 0–0 S (1) to 0–0 S (8), and in the first vibrationally excited state from 1–1 S (5) to 1–1 S(9). We derive H 2 excitation diagrams, and for the three observed dissociation fronts, the rotational excitation can be approximated with one thermal (~700 K) component representative of an average gas temperature, and one nonthermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model of the Orion Bar PDR, and find that the predicted excitation matches the data qualitatively, while adjustments to the parameters of the PDR model are required to reproduce the intensity of the 0–0 S (6) to S (8) lines.

  PublisherOA PDFDOI

• PROJECT-J: JWST observations of HH46~IRS and its outflow. Overview and first results

  arXiv (Cornell University) · 2024-04-10

  preprintOpen access

  We present the first results of the JWST program PROJECT-J (PROtostellar JEts Cradle Tested with JWST ), designed to study the Class I source HH46 IRS and its outflow through NIRSpec and MIRI spectroscopy (1.66 to 28 micron). The data provide line-images (~ 6.6" in length with NIRSpec, and up to 20" with MIRI) revealing unprecedented details within the jet, the molecular outflow and the cavity. We detect, for the first time, the red-shifted jet within ~ 90 au from the source. Dozens of shock-excited forbidden lines are observed, including highly ionized species such as [Ne III] 15.5 micron, suggesting that the gas is excited by high velocity (> 80 km/s) shocks in a relatively high density medium. Images of H2 lines at different excitations outline a complex molecular flow, where a bright cavity, molecular shells, and a jet-driven bow-shock interact with and are shaped by the ambient conditions. Additional NIRCam 2 micron images resolve the HH46 IRS ~ 110 au binary system and suggest that the large asymmetries observed between the jet and the H2 wide angle emission could be due to two separate outflows being driven by the two sources. The spectra of the unresolved binary show deep ice bands and plenty of gaseous lines in absorption, likely originating in a cold envelope or disk. In conclusion, JWST has unraveled for the first time the origin of the HH46 IRS complex outflow demonstrating its capability to investigate embedded regions around young stars, which remain elusive even at near-IR wavelengths.

  PublisherOA PDFDOI

• A far-ultraviolet–driven photoevaporation flow observed in a protoplanetary disk

  Science · 2024-02-29 · 39 citations

  articleOpen access

  Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

  PublisherOA PDFDOI

• PROJECT-J: JWST Observations of HH46 IRS and Its Outflow. Overview and First Results

  The Astrophysical Journal · 2024-05-30 · 19 citations

  articleOpen access

  Abstract We present the first results of the JWST program PROJECT-J (PROtostellar JEts Cradle Tested with JWST), designed to study the Class I source HH46 IRS and its outflow through NIRSpec and MIRI spectroscopy (1.66–28 μ m). The data provide line images (∼6.″6 in length with NIRSpec, and up to ∼20″ with MIRI) revealing unprecedented details within the jet, the molecular outflow, and the cavity. We detect, for the first time, the redshifted jet within ∼90 au from the source. Dozens of shock-excited forbidden lines are observed, including highly ionized species such as [Ne iii ] 15.5 μ m, suggesting that the gas is excited by high velocity (>80 km s −1 ) shocks in a relatively high-density medium. Images of H 2 lines at different excitations outline a complex molecular flow, where a bright cavity, molecular shells, and a jet-driven bow shock interact with and are shaped by the ambient conditions. Additional NIRCam 2 μ m images resolve the HH46 IRS ∼110 au binary system and suggest that the large asymmetries observed between the jet and the H 2 wide-angle emission could be due to two separate outflows being driven by the two sources. The spectra of the unresolved binary show deep ice bands and plenty of gaseous lines in absorption, likely originating in a cold envelope or disk. In conclusion, JWST has unraveled for the first time the origin of the HH46 IRS complex outflow demonstrating its capability to investigate embedded regions around young stars, which remain elusive even at near-IR wavelengths.

  PublisherOA PDFDOI

• A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk

  arXiv (Cornell University) · 2024-02-29

  preprintOpen access

  Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within the disks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation, finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

  PublisherOA PDFDOI

• Cooling and instabilities in colliding radiative flows with toroidal magnetic fields

  Monthly Notices of the Royal Astronomical Society · 2024-02-05 · 1 citations

  articleOpen accessSenior author

  ABSTRACT We report on the results of a simulation-based study of colliding magnetized plasma flows. Our set-up mimics pulsed power laboratory astrophysical experiments but, with an appropriate frame change, is relevant to astrophysical jets with internal velocity variations. We track the evolution of the interaction region where the two flows collide. Cooling via radiative losses is included in the calculation. We systematically vary plasma beta (βm) in the flows, the strength of the cooling (Λ0), and the exponent (α) of temperature dependence of the cooling function. We find that for strong magnetic fields a counter-propagating jet called a ‘spine’ is driven by pressure from shocked toroidal fields. The spines eventually become unstable and break apart. We demonstrate how formation and evolution of the spines depend on initial flow parameters and provide a simple analytical model that captures the basic features of the flow.

  PublisherOA PDFDOI

Frequent coauthors

• Adam Frank

  92 shared

• Ph. Nicolaï

  Centre National de la Recherche Scientifique

  88 shared

• J. M. Foster

  Atomic Weapons Establishment

  87 shared

• S. V. Lebedev

  76 shared

• T. P. Ray

  69 shared

• Y. Kato

  Gifu University

  64 shared

• Jon A. Morse

  64 shared

• Mario Livio

  64 shared