BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Finding Young Stars in the Noise: A Multi-Wavelength Detection and Classification Algorithm for Young Stellar Objects DTSTART;VALUE=DATE-TIME:20261028T182300Z DTEND;VALUE=DATE-TIME:20261028T182400Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3653@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Luke Sacco (University of Toronto/University of Hert fordshire)\nYoung Stellar Objects (YSOs) range from the beginning of star formation (protostars) up until the beginning of the main sequence (T Taur i stars). By looking at the inception of the formation process\, we can ga in insight into stellar evolution\, star-forming regions and their structu res\, and the motion of stars and surrounding matter. Using the Orion star -forming complex as a primary testing ground\, we build an algorithm desig ned to detect YSOs and their evolutionary subclasses in arbitrary regions of the sky. The algorithm combines near-infrared photometry from 2MASS\, s oft X-ray detections from eROSITA DR1\, astrometric measurements from Gaia DR3\, MIST isochrones\, and mid-infrared photometry from AllWISE and\, wh ere available\, Spitzer SEIP. Mid-infrared YSO selection follows the Koeni g & Leisawitz (2014) and Gutermuth et al. (2009) schemes\, with Spitzer ta king priority over WISE when classifiable data are available. Candidate po pulations from infrared\, X-ray\, and Gaia branches are merged and assesse d using complementary youth indicators. Across six independent star-formin g clouds\, the final mid-infrared classifier recovered approximately 82% o f YSOs with sufficient photometry for classification. For Class 0/I protos tars\, conditional recovery reached 69.8%\, while classification agreement among recovered protostars and Class II sources was approximately 95%. Mo st missed protostars were limited by catalogue availability or unclassifia ble photometry rather than colour-selection failure. These results demonst rate both the effectiveness of literature-based infrared classification wh en suitable data are available and the importance of combining complementa ry youth diagnostics to construct a portable\, all-sky YSO-selection algor ithm.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/3653/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3653/ END:VEVENT BEGIN:VEVENT SUMMARY:Reshaping the Search for Substructures in Young Protostellar Disks DTSTART;VALUE=DATE-TIME:20261028T182200Z DTEND;VALUE=DATE-TIME:20261028T182300Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3715@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Sullivan Callista (Queen's University)\nTo date\, AL MA has conducted thousands of protostellar disk observations\, and studyin g this archive has revealed much about the nature of these dusty disks aro und infant stars. Including that many of even the youngest disks contain a n indicator of planet formation: axisymmetric substructures. However\, the high computational/observational requirements of current methods mean onl y a small portion of disks have been examined for substructures. My work a ims to investigate the prevalence of substructure in young disks by develo ping a neural network that uses Simulation-Based Inference (SBI) to quickl y identify features such as gaps and rings directly from ALMA’s raw uv v isibilities. \n\nThus\, I have built a data pipeline that creates a traini ng dataset of visibilities by combining real observations of disks with kn own substructures alongside synthetic observations of real and simulated d isks. The thousands of simulated disks are generated with a range of subst ructures\, from simple smooth disks to ones with multiple gaps and rings\, and each one is synthetically observed with a range of positional and obs ervational parameter values. This variety ensures that the dataset mimics the breadth of qualities found across real observations. \n\nOnce this SBI model is complete\, it will be able to identify a disk’s most likely su bstructure(s) in seconds\, instead of the hours required by conventional t echniques. By creating this model and running it over every viable young d isk in ALMA’s archive\, I aim to shift the current paradigm from analysi ng individual disks to analysing the presence\, form\, and statistics of s ubstructure among large disk populations.\n\nhttps://nyx.physics.mcgill.ca /event/587/contributions/3715/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3715/ END:VEVENT BEGIN:VEVENT SUMMARY:Tracing Star Formation Histories in the Local Neighborhood using Y oung Stellar Associations DTSTART;VALUE=DATE-TIME:20261028T182100Z DTEND;VALUE=DATE-TIME:20261028T182200Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3707@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Sargun Jassal (University of Toronto)\nYoung stellar associations provide an opportunity to investigate the recent star format ion history of the Solar Neighborhood by identifying groups of stars that share similar ages and kinematic properties. In this work\, I investigate two nearby young stellar associations\, SCYA 75 (Ophiuchus Southeast) and SCYA 103 (Scorpius-Centaurus)\, to explore whether their stellar populatio ns show evidence of differences in their formation histories. I used a loc al k-neighborhood search to identify nearby stellar members and characteri ze the local stellar populations associated with each region. I then compa red the age distributions and statistical properties of the identified pop ulations to investigate similarities and differences between the two assoc iations. By examining the ages of stars in these neighboring regions\, thi s study aims to provide insight into the timing and structure of recent st ar formation in the local solar environment. This approach demonstrates ho w spatially localized stellar population searches can be used to connect i ndividual young associations to the broader star formation history of the Solar Neighborhood.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributio ns/3707/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3707/ END:VEVENT BEGIN:VEVENT SUMMARY:First Mid-Infrared Characterization of the Galactic Center WR Star Population DTSTART;VALUE=DATE-TIME:20261028T182000Z DTEND;VALUE=DATE-TIME:20261028T182100Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3676@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Zachary Ireland (University of Toronto)\nThis resear ch presents the first mid-infrared characterization of the Galactic Center (GC) Wolf-Rayet (WR) and Ofpe/WN9 star population using integral-field sp ectroscopy from the JWST Mid-Infrared Instrument MRS. Data consist of cali brated\, three-dimensional FITS spectral cubes spanning λ∈[4.9\, 27.9] μm at resolving power R∈[1330\, 3750]. As an initial application\, the spectrum of the Ofpe/WN9 star IRS 16NW is analyzed in Channel 1\, being co rrected for extinction\, foreground H₂O rovibrational absorption\, defec ts\, and back/foreground emission. Spectral features are identified and de blended with multi-component Gaussian or quartic fits\, then assessed for association with IRS 16NW using measurements of its line-of-sight velocity and expected line width. \n\nWR and Ofpe/WN9 stars undergo radiatively dr iven mass loss through stellar winds. Expelled material from approximately 30 WR or Ofpe/WN9 stars is consistent with supplying all material availab le for accretion onto Sgr A*\; wind metallicity can therefore have implica tions for the accretion rate: higher metal abundances enhance radiative co oling\, allowing shocked winds to lose thermal pressure support and reach smaller radii. By identifying the intrinsic mid-IR spectral contributions of these stars and separating them from surrounding GC structures\, the an alysis further constrains the composition/metallicity of the accretion env ironment of Sgr A*. Metal-line ratios are derived either directly from det ected stellar emission or\, for non-detections\, constrained using Monte C arlo injection-recovery tests.\n\nhttps://nyx.physics.mcgill.ca/event/587/ contributions/3676/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3676/ END:VEVENT BEGIN:VEVENT SUMMARY:Searching for Precursor Outbursts in 2024jlf DTSTART;VALUE=DATE-TIME:20261028T181900Z DTEND;VALUE=DATE-TIME:20261028T182000Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3684@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Ai Hua Li (Dunlap Institue for Astronomy & Astrophys ics)\nType IIn supernovae (SNe) are a subclass of Type II SNe characterize d by narrow hydrogen emission lines produced by interactions between SN ej ecta and surrounding circumstellar material (CSM). Some Type IIn SNe show these features only briefly\, indicating less extended CSM and motivating their classification as Type IIn-like SNe. The origin of this CSM remains a major outstanding question.\n\nPrecursor outbursts are episodes of enhan ced mass loss from a progenitor prior to explosion theorized to contribute to CSM formation. They have been observed in approximately 25–50% of Ty pe IIn SNe\, but only one Type IIn-like progenitor has been linked to prec ursor activity. We therefore investigate possible pre-SN variability in th e progenitor of the Type IIn-like SN 2024jlf.\n\nUsing data from the ATLAS Forced Photometry Service\, we applied the ATClean pre-SN variability ana lysis pipeline. ATClean cleans progenitor and control light curves\, searc hes for sustained signals across Gaussian-kernel timescales\, and estimate s detection efficiency by injecting simulated precursor outbursts into con trols.\n\nATClean detected sustained pre-SN signals across all tested time scales. Binning the cleaned progenitor light curve revealed >5σ detection s in the same time range. However\, difference images revealed variability in a nearby image artefact during the epoch of detections\, and ATClean ’s binning procedure is susceptible to outliers.\n\nFuture work such as investigating the above artefacts and refining the ATClean binning procedu re is needed to determine the exact source of our detections\, thereby con straining pre-SN mass loss in IIn-like systems.\n\nhttps://nyx.physics.mcg ill.ca/event/587/contributions/3684/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3684/ END:VEVENT BEGIN:VEVENT SUMMARY:Rapid Rotation of a Cold Extremely Metal-poor Brown Dwarf DTSTART;VALUE=DATE-TIME:20261028T181700Z DTEND;VALUE=DATE-TIME:20261028T181800Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3708@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Jerry J.-Y. Zhang (Western University)\nWe report th e first detection of brightness variability in an extremely metal-poor bro wn dwarf. These objects are ancient\, very low-mass members of the Milky W ay that formed when the Galaxy contained far fewer heavy elements than it does today. Using the 10.4-m Gran Telescopio Canarias\, we found that the nearest known extreme T subdwarf\, WISEA\,J181006.1$-$101000.5\, changes i ts $J$-band brightness by $1.14\\pm0.26%$ every $73.7\\pm1.5$ minutes. We interpret this periodic signal as the rotation of an uneven atmosphere int o and out of view. The object completes a rotation about 8 times faster th an Jupiter\, similar to watching changing cloud patterns on a rapidly rota ting Jupiter. An independent measurement of its projected rotational veloc ity\, $v\\sin i = 125^{+25}_{-23}\\ {\\rm km\,s^{-1}}$\, confirms that the object is an extremely fast rotator. Such rapid rotation may be a natural consequence of its old age and compact size: unlike stars\, these ultraco ol objects have no efficient mechanism to slow their rotation over billion s of years. This first detection opens a new window into the atmospheres a nd rotation of the oldest ultracool objects in the Galaxy.\n\nhttps://nyx. physics.mcgill.ca/event/587/contributions/3708/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3708/ END:VEVENT BEGIN:VEVENT SUMMARY:Forecasting The Weather On Ultra-Hot Worlds: A High-Resolution Stu dy of WASP-189b DTSTART;VALUE=DATE-TIME:20261028T181500Z DTEND;VALUE=DATE-TIME:20261028T181600Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3714@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Jason Gabriel (University of Waterloo)\nExceeding te mperatures of up to 3\,300K\, WASP—189b's dayside hemisphere is a unique laboratory in which we can probe the extreme atmospheric conditions exper ienced by the population of ultra-hot Jupiter (UHJ) exoplanets. Using high -resolution observations from GHOST on Gemini South\, we detect various me tals within WASP—189b's atmosphere\, alongside a first tentative detecti on of neutral potassium using the Doppler cross-correlation method. Our wo rk details the exploration of using such detections to study atmospheric p atterns on this planet\, providing a first step toward forecasting global weather conditions.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributio ns/3714/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3714/ END:VEVENT BEGIN:VEVENT SUMMARY:Developing a Recurrent U-Net for Faint Trans-Neptunian Object Dete ction Using Synthetic Injections DTSTART;VALUE=DATE-TIME:20261028T175500Z DTEND;VALUE=DATE-TIME:20261028T180500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3642@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Malavika Nair (Western University)\nTrans-Neptunian Objects (TNOs) are small\, distant bodies beyond Neptune that provide impo rtant context on the formation and evolution of the outer Solar System. Ho wever\, the faintest TNOs are difficult to detect because their weak signa ls can be easily confused with noise and subtraction artifacts. Manual ide ntification of genuine TNOs is therefore a time-consuming process that can require hours of careful inspection. To automate the process\, this proje ct develops a recurrent U-Net framework for identifying faint moving sourc es\, with particular emphasis on generating realistic and well-characteriz ed training data. A synthetic injection pipeline\, maketensor\, was develo ped to implant artificial TNOs directly into real difference-image observa tions. Each source is propagated across multiple exposures with physically motivated apparent motion and injected using the point-spread function co rresponding to each observation. The underlying noise\, stellar residuals\ , detector features\, and other observational artifacts are preserved to k eep the training data authentic. The pipeline also reproduces characterist ic subtraction effects and negative wells\, allowing the synthetic objects to more closely resemble real TNO signatures. The resulting multi-frame t ensors contain real observational backgrounds with exact ground-truth loca tions and trajectories for every injected source. These sequences are used to train a recurrent U-Net to produce pixel-wise probability maps that id entify likely TNO locations across a sequence of exposures. By learning th e consistent motion of a TNO across successive frames\, the network aims t o distinguish genuine moving sources from noise and image-subtraction resi duals\, enabling faster and more reliable detection of faint TNOs in large astronomical datasets.\n\nhttps://nyx.physics.mcgill.ca/event/587/contrib utions/3642/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3642/ END:VEVENT BEGIN:VEVENT SUMMARY:Exploring Convective Boundary Mixing Through Stellar Pulsations DTSTART;VALUE=DATE-TIME:20261028T174500Z DTEND;VALUE=DATE-TIME:20261028T175500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3627@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Serena Davis (Mount Allison University)\nConvective boundary mixing occurs at the boundaries between convection and radiation zones in stars\, where the material in the convection zone crosses the con vective boundary. This can change the location of the convective boundary and bring more hydrogen into the core of the star\, which has many effects on its evolution\, including an extended main sequence lifetime. We use 1 D stellar evolution code MESA (Modules for Experiments in Stellar Astrophy sics) to make models of stars with various convective boundary mixing proc esses\, and calculate pulsation frequencies for the models with the GYRE s tellar oscillation code. We then use the pulsation frequencies of the mode ls to compare the effects of these different processes\, and their impleme ntations in MESA\, on the star. Our goal is to find some difference caused by the different convective boundary mixing processes that could potentia lly be observed in real stars. This will help us understand how these proc esses occur in stars\, enabling more accurate predictions of stellar evolu tion.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/3627/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3627/ END:VEVENT BEGIN:VEVENT SUMMARY:EncoTESS: Age Inference from Raw TESS Light Curves DTSTART;VALUE=DATE-TIME:20261028T173500Z DTEND;VALUE=DATE-TIME:20261028T174500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3640@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Phil Van-Lane (University of Toronto\; University of California San Diego)\nStellar ages are a foundational component of astro nomy research\, but are notoriously difficult to measure for low mass main sequence stars. Fortunately\, variability indicators such as rotation per iod\, flaring rate\, and amplitude of flux variability can provide some ag e constraints\, but they evolve in nonlinear and non-monotonic ways. Furth ermore\, these indicators are typically characterized as summary statistic s from time series data\, but these are often noisy\, treated independentl y\, and do not capture all of the useful information contained in raw ligh t curves. With the recent advances in ML/AI and computing combined with th e vast number of light curves available from Kepler and TESS\, there is a prime opportunity to apply more data-driven methods. To that end\, I have developed and here present \\texttt{EncoTESS}: a Time Series Foundation Mo del that can be used to estimate stellar ages from raw TESS light curves w ithout using summary statistics. I show that through self-supervised train ing\, \\texttt{EncoTESS} naturally captures stellar variability\, and that it can be used to infer the ages of young M dwarfs with more accuracy and precision than rotation-based models. \\texttt{EncoTESS} is designed with consideration of crucial systematics such as noisy\, heteroskedastic data with large gaps\, and implements an architecture expandable to multi-cade nce and multi-survey light curves for broader applicability in the future. It is also ~1% of the size of typical literature Time Series Foundation M odels\, and can be run easily on any modern laptop.\n\nhttps://nyx.physics .mcgill.ca/event/587/contributions/3640/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3640/ END:VEVENT BEGIN:VEVENT SUMMARY:Freckled and Flaring: Statistical Starspot Mapping on M Dwarfs via Stellar Flares DTSTART;VALUE=DATE-TIME:20261028T172500Z DTEND;VALUE=DATE-TIME:20261028T173500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3644@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Rohan Kumar ()\nThe spatial distribution of starspot s on red dwarf stars remains an open question in stellar astrophysics. Und erstanding whether red dwarfs’ starspots are preferentially equatorial —akin to the Sun—or are preferentially polar can give us insight into how these generate their magnetic dynamos and help to better characterize the atmospheres of the planets that orbit them as atmospheric observations are heavily contaminated by starspots. Most tested surface mapping techni ques are either observationally expensive or highly degenerate\, making it difficult to obtain a population-level understanding of starspot distribu tions. Fortunately\, stellar flares\, which result from magnetic reconnect ion events that are spatially correlated with starspot locations on the Su n\, make flare observations a powerful diagnostic of starspots on distant stars. I have developed and rigorously tested a framework to detect stella r rotation and energetic flares in light curves from NASA’s Transiting E xoplanet Survey Satellite\, which I am using to correlate flare times with stellar rotational phase as a proxy for the distribution of starspots. My early analysis of over 6\,500 red dwarfs suggests that\, regardless of th e interior stellar dynamo\, these stars are dominated by equatorial starsp ots.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/3644/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3644/ END:VEVENT BEGIN:VEVENT SUMMARY:GAUCHO: Searching for Planets Around the Coolest Stars in the Gala xy DTSTART;VALUE=DATE-TIME:20261028T171500Z DTEND;VALUE=DATE-TIME:20261028T172500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3659@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Flavie Bélanger (UdeM/IREx)\nUltra-cool dwarfs are the smallest and coolest stars on the main sequence. While M dwarfs are ge nerally known to harbour a large number of planets\, including rocky\, Ear th-mass exoplanets\, the occurrence rate and architectures of planetary sy stems around ultra-cool dwarfs remain poorly constrained. To date\, the on ly well-characterized planetary system around an ultra-cool dwarf is the T RAPPIST-1 system. This regime is the last to be constrained by radial-velo city studies. The Grasping exoplanet Architectures of Ultra-Cool HOsts (GA UCHO) project is a blind radial velocity survey of about 15 ultra-cool dwa rfs with the NIRPS high-resolution spectrograph. In the long term\, GAUCHO aims to constrain the occurrence rate of systems like TRAPPIST-1 and supe r-Earths around ultra-cool dwarfs\, map typical long-orbit architectures ( >10 days) of ultra-cool dwarf systems\, and measure their fraction of brow n-dwarf companions. Here\, we give an overview of the GAUCHO target sample and present preliminary results focusing on target selection for prolonge d observations within the NIRPS GTO program. These results highlight the s ignificant challenges associated with blind radial velocity searches of fa int targets.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/3659 / LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3659/ END:VEVENT BEGIN:VEVENT SUMMARY:Determining Stellar Inclinations and True Planet Mass with RVs DTSTART;VALUE=DATE-TIME:20261028T170500Z DTEND;VALUE=DATE-TIME:20261028T171500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3666@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Riley Rosener (Université de Montréal)\nI aim to d etermine the inclination of the rotation axis of stars that host exoplanet s and to use that information to find the true mass of their exoplanets. T o detect exoplanets via the radial velocity method\, one measures the minu te redshifts and blueshifts in a star’s spectrum as a star’s planet ca uses orbital reflex motion towards and away from the observer. The strengt h of the radial velocity signal depends on the planet’s mass and its a p riori unknown orbital inclination–the rotational plane tilt relative to the observer. Without knowing the inclination\, the radial velocity techni que can only provide a lower limit on the planet mass–a limitation for t he past 30 years. If one can find the stellar rotation axis inclination an d assumes that the planet’s orbital inclination is perpendicular to the stellar rotation axis\, one can find the planet’s true mass. My research investigates a new method of determining the stellar rotation axis from R V observations by analyzing and modeling the changes in both stellar radia l velocity and surface temperature shifts as a function of time. I use dat a from the NIR spectrographs NIRPS and SPIRou and reduce it via the line-b y-line technique (LBL) to measure both the stellar RV and temperature vari ations (dTemp)\, modeling the outputs with starry and fitting the stellar rotation axis inclination with MCMC sampling\, from which a true planet ma ss can be found.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/ 3666/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3666/ END:VEVENT BEGIN:VEVENT SUMMARY:Oxygen abundances as a key predictor of small planet hosts using g radient boosted decision trees DTSTART;VALUE=DATE-TIME:20261028T165500Z DTEND;VALUE=DATE-TIME:20261028T170500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3635@nyx.physics.mcgill.ca DESCRIPTION:Speakers: Rosalind Liang (University of Victoria)\nUsing a nov el crossmatch of GALAH DR4 stellar abundances with K2 and TESS planet dete ctions\, we apply the gradient boosted decision tree ensemble model XGBoos t to investigate relative importances of specific chemical abundances and molar ratios in predicting small planet hosts. In contrast to previous stu dies\, we find a consistently high feature importance for oxygen across mo dels. Using a probability threshold of P > 0.80\, the [X/O] ensemble ident ifies 1\,218 likely small-planet hosts\, including 13 of 133 K2/TESS candi dates. Abundance distributions reveal that the observed signal may be driv en primarily by oxygen depletion. These results provide a targeted shortli st for follow-up observations while highlighting the need for larger host samples and more granular comparisons between planetary subclasses.\n\nhtt ps://nyx.physics.mcgill.ca/event/587/contributions/3635/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3635/ END:VEVENT BEGIN:VEVENT SUMMARY:Can Super-Earths Be Born Rocky? Separating Survey Selection from F ormation in the Deficit of Large Rocky Planets at Low Insolation DTSTART;VALUE=DATE-TIME:20261028T164500Z DTEND;VALUE=DATE-TIME:20261028T165500Z DTSTAMP;VALUE=DATE-TIME:20261022T065303Z UID:indico-contribution-51-3669@nyx.physics.mcgill.ca DESCRIPTION:Speakers: HongYi Mei (University of Toronto)\nSmall planets sh ow a radius valley near 1.8 R⊕ splitting them into rocky super-Earths an d volatile sub-Neptunes\, but whether rocky planets can be born rocky\, or are all stripped cores of planets that lost an envelope\, is still unsett led. We test two planet formation scenarios\, Sub-Neptune (no planet born rocky) and Sub-Neptune+Super-Earth (some are)\, as priors to analyze this question. We build the scenarios by building synthetic planet populations\ , where we tested two independent generators (occurrence-weighted P-Pop an d a flat uniform-parameter control). The two scenarios are then pushed thr ough calibrated Kepler\, TESS\, and HARPS/NIRPS detection pipelines\, and compared against the NASA Exoplanet Archive\, filtered with precision cont rol ≤25% mass/≤8% radius uncertainty (125 planets after the filter). T he analysis in comparison with NASA include a forward Monte Carlo comparis on and a Bayesian posterior-predictive test\, during which we used a metri c based on the detected population's rocky-to-volatile fraction. As for th e result\, at low insolation (S < 50 I⊕)\, the 25 NASA cold super-Earths favor Sub-Neptune under every relation and both generators (√x = 2.10 v s 6.25 in the Bayesian test). An important thing to note is that absolute completeness of detection in this cold regime is only ~1%\, driven almost entirely by the ~2% geometric transit probability of long orbits\, rather than photometric sensitivity\, so the raw scarcity of cold rocky planets a lone says nothing until assessed in detected space. We also finds that the result fails when the uncertainty control is relaxed from ≤25% mass/≤ 8% radius to ≤30% mass/≤10%\, and only 4 of 25 cold super-Earths are rocky at high confidence. In conclusion\, we read the result as most rocky super-Earths coming from atmospheric escape rather than being born rocky. We believe that identifing more precise cold-planet masses\, concentrated among K/M dwarfs\, where detection efficiency stays near 50%\, are needed to settle it.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributions/36 69/ LOCATION:Online URL:https://nyx.physics.mcgill.ca/event/587/contributions/3669/ END:VEVENT END:VCALENDAR