Measuring the Spot Variability of T Tauri Stars Using Near-infrared Atomic Fe and Molecular OH Lines
Year: 2024
Type: article
Abstract: As part of the Young Exoplanets Spectroscopic Survey, this study explores the spot variability of 13 T Tauri Stars (TTSs) in the near-infrared H band, using spectra from the Immersion GRating INfrared Spectrometer. By analyzing effective temperature (T eff) sensitive lines of atomic Fe i at ∼1.56259 μm and ∼1.56362 μm, and molecular OH at ∼1.56310 and ∼1.56317 μm, we develop an empirical equivalent width ratio (EWR) relationship for T eff in the range of 3400–5000 K. This relationship allows for precise relative T eff estimates to within tens of Kelvin and demonstrates compatibility with solar metallicity target models. However, discrepancies between observational data and model predictions limit the extension of the T eff–EWR relationship to a broader parameter space. Our study reveals that both classical and weak-line TTSs can exhibit T eff variations exceeding 150 K over a span of 2 yr. The detection of a quarter-phase delay between the EWR and radial velocity phase curves in TTSs indicates spot-driven signals. A phase delay of 0.06 ± 0.13 for CI Tau, however, suggests additional dynamics, potentially caused by planetary interaction, inferred from a posited 1:1 commensurability between the rotation period and orbital period. Moreover, a positive correlation between T eff variation amplitude and stellar inclination angle supports the existence of high-latitude spots on TTSs, further enriching our understanding of stellar surface activity in young stars.
Source: The Astrophysical Journal
Institutions: Lowell Observatory, Rice University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, Yale University, Rice University, Northern Arizona University, Space Telescope Science Institute, Universität Wien, Nuclear Safety and Security Commission, Korea Astronomy and Space Science Institute, Uppsala Universitet
Awards: MRI: Development of a High Resolution Infrared Spectrograph with a Large Spectral Grasp, INSPIRE: Modeling the Magnetic Interactions between Stars and Planets, G2100528408, GUIDING QUESTION: HOW TO ACQUIRE SUSTAIN AND NURTURE LIFE-ESSENTIAL CHEMICAL INGREDIENTS ON THE SURFACE OF ROCKY PLANETS? BUILDING A HABITABLE ENVIRONMENT ON INNER SOLAR SYSTEM ROCKY SURFACES REQUIRES THE LIFE-ESSENTIAL CHEMICAL INGREDIENTS (C N O H S AND P) TO JOURNEY THROUGH A SERIES OF ASTRONOMICAL PLANETARY GEOLOGICAL AND GEOCHEMICAL PROCESSES DURING PLANET FORMATION AND EARLY PLANETARY EVOLUTION. HOWEVER IN MOST STUDIES ONLY ONE OR FEW OF THESE STEPS ARE INVESTIGATED IN ISOLATION AS CONDITIONS OF HABITABILITY AND THE CONSEQUENCES OF MULTIPLE PATHWAYS THAT MAY BE FEASIBLE ARE NOT RIGOROUSLY EXPLORED. SIMILARLY MOST STUDIES TRACKING THE IMPACT OF PREBIOTIC PROCESSES CONSIDERED THE ORIGIN OF WATER ALONE AND COMPREHENSIVE STUDIES ON A COMBINATION OF LIFE-ESSENTIAL ELEMENTS ARE LACKING. IN ORDER TO EVALUATE THE PATHWAYS THAT MAY LEAD TO EARLY HABITABLE CONDITIONS IN MULTIPLE PLANETARY SURFACES BUT SUSTENANCE ONLY IN A SUBSET AN INTERDISCIPLINARY APPROACH TO STUDY THE EARLY CYCLES OF ALL KEY INGREDIENTS ARE NECESSARY. THIS CAN 8 NAI NODE PROPOSAL AIMS TO CONSTRAIN THE PATHWAYS THAT LEAD TO THE ACQUISITION SUSTENANCE AND NURTURING OF THE LIFE-ESSENTIAL CHEMICAL ELEMENTS AT THE SURFACE AND NEAR-SURFACE ENVIRONMENTS OF ROCKY DIFFERENTIATED PLANETARY BODIES LEADING TO HABITABILITY AND POTENTIALLY DRIVING THE FORMATION OF PREBIOTICALLY-RELEVANT ORGANIC MOLECULE PRECURSORS WITHIN THE FIRST BILLION YEARS OF A PLANET S EVOLUTION. OUR TEAM MEMBERS BRING EXTENSIVE EXPERTISE IN ASTROPHYSICS GEOLOGY GEOCHEMISTRY GEOPHYSICS FLUID AND ATMOSPHERIC DYNAMICS CLIMATE SCIENCE AND ORGANIC CHEMISTRY; AN OVERARCHING GOAL IS TO TRACE THE LIFE-ESSENTIAL ELEMENTS FROM PROTOPLANETARY DISKS TO EARLY PREBIOTIC MOLECULES ON THE SURFACES OF ROCKY PLANETS WITH A PARTICULAR EMPHASIS ON THE FEEDBACKS AMONG INTERIOR SURFACE AND ATMOSPHERIC PROCESSES. WE WILL USE OBSERVATIONS FROM OUR OWN SOLAR SYSTEM IN TERMS OF COMPARATIVE PLANETOLOGY BUT WILL ALSO CONSTRUCT POSSIBLE PATHWAYS THAT MAY LEAD TO THERMO-CHEMICAL HABITABILITY WHICH CAN BE UTILIZED FOR EXPLORATION OF OTHER SOLAR SYSTEMS IN SEARCH FOR LIFE. THE PROPOSED RESEARCH COMPLEMENTS THE ACTIVITIES OF THE CAN 7 TEAMS BECAUSE NONE OF THE CURRENT TEAMS ARE INVESTIGATING THE CYCLES OF THE KEY INGREDIENTS DURING DIFFERENTIATION AND EARLY TECTONO-MAGMATIC AND GEOCHEMICAL EVOLUTION OF ROCKY PLANETS. OUR PROPOSAL WILL BRING IN THE UNIQUE INTERDISCIPLINARY PERSPECTIVE OF CYCLES OF KEY INGREDIENTS OF LIFE THROUGH DEEP TIME FROM GEOLOGIC PLANETARY GEOPHYSICAL AND GEOCHEMICAL PERSPECTIVES. GIVEN THE INTERDEPENDENT NATURE OF THE PROPOSED ACTIVITIES AMONG SEEMINGLY DISPARATE FIELDS OF RESEARCH THE SCOPE OF THIS PROPOSAL CAN ONLY BE SUPPORTED THROUGH AN INSTITUTE WITHOUT WALLS . RELEVANCE TO THE GOALS OF THE ASTROBIOLOGY PROGRAM: THE PROPOSED INVESTIGATION IS RELEVANT FOR SEVERAL OF THE GOALS OF THE ASTROBIOLOGY PROGRAM AS OUTLINED IN THE 2015 STRATEGY INCLUDING THE CENTRAL THEMES OF CONSTRUCTING HABITABLE WORLDS AND IDENTIFYING EXPLORING AND CHARACTERIZING ENVIRONMENTS FOR HABITABILITY AND BIOSIGNATURES . OUR PROPOSAL WILL DIRECTLY ADDRESS QUESTIONS SUCH AS HOW DOES THE STORY OF EARTH IN PARTICULAR IT S PAST INFORM US ABOUT HOW THE CLIMATES ATMOSPHERIC COMPOSITIONS INTERIORS AND BIOSPHERES OF PLANETS CAN CO-EVOLVE? BECAUSE OUR TEAM WILL STUDY THE INTERACTIONS OF INTERIOR ATMOSPHERE AND CLIMATE IN THE FIRST BILLION YEARS OF A ROCKY PLANETS EVOLUTION KEEPING IN MIND THE HISTORY OF THE EARTH AS AN ANALOG. OUR PROPOSAL WILL ALSO DIRECTLY ADDRESS QUESTIONS SUCH AS WHAT ARE THE FUNDAMENTAL INGREDIENTS AND PROCESSES THAT DEFINE A HABITABLE ENVIRONMENT? BECAUSE WE WILL TRACK THE FATE OF THE LIFE-ESSENTIAL ELEMENTS THROUGH THE FUNDAMENTAL PROCESSES OF PLANET FORMATION AND EARLY GEOLOGIC AND BIOGEOCHEMICAL EVOLUTION WITH THE GOAL OF OUTLINING POSSIBLE PATHS THAT ARE OR ARE NOT FAVORABLE IN FINALLY HARBORING THE COHNSP SPECIES AT THE PLANETARY SURFACES., Enabling a New Instrument 'IGRINS' for the Gemini South Telescope User Community, Collaborative Research: Observing Exoplanet Atmospheres at High Resolution
OpenAlex ID: W4402845985