Research Report for 2021

Professor Patrick Hartigan's research involved the formation of stars, stellar jets, emission nebulae, the physics of shock waves, and time-domain astronomy in 2021. A full list of publications is available on the Web, as are overview pages that describe research areas of young stars and stellar jets.

Massive Star Forming Regions/JWST:Hartigan is leading a project to obtain orbital parameters for newly-discovered young eclipsing binaries in the Carina massive star formation region. Eclipsing binaries are the most reliable way to test pre-main-sequence evolutionary tracks because the primary and secondary must have the same ages. The eclipsing binary data allows us to measure the radii and temperatures of each star accurately, making it possible to find their individual ages. Only a handful of young eclipsing binaries are known, so new discoveries of these objects are an important constraint to the theory. We have spectra of several candidate young stars with the 4-m SOAR telescope in Chile.

Hartigan is a collaborator on one of the fifteen large proposals accepted in the first round for the James Webb Space Telescope (JWST; O. Berne PI). The proposal will study the Orion Bar region as a means to test a variety of instruments on the telescope once it launches.

Stellar Jets: A second project, led by B. Nisini in Rome, images regions very close to protostars in an attempt to learn how jets are launched. The Hubble Space Telescope portion of this project was published in 2021 in the Astrophysical Journal, and a companion project with the James Webb Space Telescope has now been approved and should begin acquiring data sometime in late 2022.

ALMA and Gemini Studies of Photodissociation Regions:With Rice assistant professor Andrea Isella and graduate student Maxwell Hummel, Hartigan continued to analyze data cubes of three isotopologues of CO and C within a bright region of photodissociation in the Carina Nebula with the the Atacama Large Millimeter Array in Chile. Together with existing H2 observations and new ALMA CO and CS maps of the region, we now have the first high-resolution maps that trace gas from where it is molecular deep within the dark cloud, to its atomic stage, to where it becomes ionized at the dissociation front, a process which occurs in all regions of massive star formation. 

Time Domain Studies:In 2019, Hartigan led a team that successfully acquired a full month of time on the Blanco NOAO 4-m telescope in Chile to study variability in the Carina star formation region with the Dark Energy Camera (DECam). This imager has a full field of view of over 2 degrees, and is ideal for monitoring light variations of the thousands of young stars present in this region. Variability holds clues to many aspects of the star formation process, including rotational properties, obscuration by dusty envelopes, starspot coverage, accretion and flares. We continue to reduce and analyze these data. Results from the project will presage what the Large Synoptic Survey telescope may accomplish in this arena.

Large Synoptic Survey Telescope and a future UV Space Telescope:  Hartigan is part of the Transient and Variable Stars group of the Large Synoptic Survey Telescope, a facility under construction in Chile that will survey the entire sky visible from that location every three days. These data will usher in a new era of `time-domain astronomy', requiring astronomers to sort through vast amounts of data in a short time. The LSST subgroups are tasked with optimizing the time cadences for their objects.

Campus Observatory and Outreach Activities: The Rice University Campus Observatory (RUCO), located on the roof of the Brockman Physics building continues to be the workhorse for our undergraduate major and nonmajor courses. Hartigan recollimated the telescope optics to provide good images with our new CCD, and allowed the lab class for undergraduates to proceed normally despite the Covid-induced shutdown at McDonald. We have a new spectrograph we will be installing in 2022. Hartigan gave several interviews regarding the James Webb Space Telescope and eclipses during the year. Observatory schedules can be found on the observatory website.

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Patrick Hartigan