Peering into the physics of brown dwarfs: spectroscopy with JWST/ NIRSpec Catarina Alves de Oliveira, European Space Agency Understanding the Nearby Star-forming Universe with JWST 27 Aug 2019 ESA UNCLASSIFIED – Releasable to the public
The NIRSpec GTO program - GTO program built for scientific excellent, but also ensuring that the observations probe key modes, strategies and regimes to provide early feedback to the community https: / / www.cosmos.esa.int/ web/ jwst-nirspec-gto - 17h (~ < 2% ) dedicated to the ‘Physics of Brown Dwarfs” program, with focus-team: - C. Alves de Oliveira, K. Luhman, R. Parker, P. Tremblin, I. Baraffe, G. Chabrier Collaboration w/ M. McCaughrean for ONC program ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 2
Science case: The Physics of Brown Dwarfs - Physics of brown dwarfs challenge several areas from the theory of star and planet formation to the physics of cool atmospheres - Goal: Discovery and spectral characterization of the coldest and least massive brown dwarfs to advance these fields ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 3
Science case: The Physics of Brown Dwarfs Program is divided into two parts aimed at: I. Testing star formation models by finding and characterizing the lowest mass young planetary- mass brown dwarfs (IC 348 and ONC) II. Testing models of cool atmospheres by studying the coldest known brown dwarf in the solar neighborhood (WISE0855) ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 4
I. Testing star formation models with young, planetary-mass brown dwarfs Obtain spectra of low mass young brown-dwarfs in nearby star-forming regions to: i. probe the cut-off mass limit of star formation, and the mass function across the planetary-mass regime, ii. investigate the presence of heavy elements enrichment as a clue to the formation process Atmospheric models from P . Tremblin, I. Baraffe, G. Chabrier The effect of m etallicity: Young Jupiter-mass object: Teff: 1200K, logg: 4, log K zz : 0 Metallicity: Solar vs 5 xSolar ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 5
Target selection: IC 348 Distance: 316 pc Size: ~ 2.6x2.3 pc (~ 34’x28’) Age: 2Myr Population: 478 spectroscopically confirmed members Aladin/WISE Caltech ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 6
What is the dynamical history of IC 348? Minimum-spanning-tree method to quantify degree of mass segregation * : average random path length ‘mass segregation ratio’ ( Λ MSR ) = path length of massive stars (or brown dwarfs) ! No evidence that m ass segregation has occurred at 2 Myr in I C3 4 8 . Parker & Alves de Oliveira 2017 ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 7
What were the initial conditions for star and planet formation in IC348? N-body simulations of the dynamical evolution of star-forming regions with varying initial densities to characterize spatial structure and density * . quanti fi es and distinguishes between mean distance between stars , substructured and centrally ! -parameter = concentrated regions. mean length of the minimal spanning tree ! Observational value suggests less-dense initial conditions in I C3 4 8 , and a m odest degree of dynam ic evolution. Parker & Alves de Oliveira 2017 ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 8
What was the impact of dynamical evolution on star and planet formation in IC348? N-body simulations of a young cluster with the dynamical history and initial conditions of IC348, to examine the direct effects of interactions in the cluster on stars and planetary systems. Sim ulation set-up: - Cluster: based on our findings of most likely initial conditions - Prim ary stars: 400 stars randomly drawn from an IMF - Stellar com panions: assigned based on binary fractions associated with the primary mass - Planetary com panions: 1 Jupiter mass planet on a 30 AU orbit is assigned to single stars Parker & Alves de Oliveira 2017 ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 9
What was the impact of dynamical evolution on star and planet formation in IC348? è After ~ 2 Myr, ~ 3 to 7 planets initially orbiting their parent star at 30AU, have been liberated and became free- floating planets è This is significantly less than what was found for an Orion-like simulation, where ~ 10% of planetary companions were liberated Parker & Alves de Oliveira 2017 ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 10
Spectroscopy with JWST Near-IR MOS/ NI RSpec (vs slitless NIRCam & NIRISS) + More sensitive by ~ 2-5x + Reduces contamination/ confusion + Can block saturating sources within field + Higher spectral resolution options + Larger wavelength range coverage - No blind searches possible - Requirements on targets’ astrometric accuracy - Needs target acquisition - PSF truncation - Aperture corrections ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 11
JWST/ NIRSpec: MOS observing mode Multi-Object spectroscopy (MOS) FOV: ~ 9 arcmin 2 ➡ Rich fields, extended targets Apertures: ~ 0.2x0.4 arcsec, ~ 1/ 4 million micro-shutters Resolution: ~ 100, ~ 1000 (~ 2700, partial truncation) Credit: NASA Credit: NASA Credit: NASA ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 12
JWST/ NIRSpec: wavelength coverage and resolution Multi-Object spectroscopy (MOS) ➡ Rich fields, extended targets Integral Field Spectroscopy (IFS) ➡ Sources with few arcsec extent JWST spectroscopy comes in many flavours! Fixed Slits (FS) ➡ Single sources, bright stars Bright Object Time Series (BOTS) ➡ Exoplanets ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 13
JWST/ NIRSpec: field of view Multi-Object spectroscopy (MOS) ➡ Rich fields, extended targets Integral Field Spectroscopy (IFS) ➡ Sources with few arcsec extent Fixed Slits (FS) ➡ Single sources, bright stars Bright Object Time Series (BOTS) ➡ Exoplanets ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 14
JWST/ NIRSpec: multiplexing Density of targets Slitlet configuration Multiplexing depends Length of slitlet and dithering strongly on the density of strategy place constraints on targets in the input catalog the number of observable objects and therefore multiplex Credit: NASA Credit: P. Jakobsen Target centering Viable shutters Shutter availability for an Constraints on target observation depends on its centering are relevant for operability status, avoidance spectro-photometric accuracy, of spectral overlap, or but impact multiplexing spectral truncation Credit: P. Jakobsen Credit: JWST User documentation (STScI) ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 15
JWST/ NIRSpec: multiplexing On the densest target fields, estimated maximum number of targets that can be R~100 observed in single exposure without their spectra overlapping: ~ 200 targets for R~ 100 PRISM ~ 60 targets for R~ 1000 gratings R~1000 Courtesy of P. Jakobsen (DAWN, former ESA/ JWST Project Scientist) ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 16
JWST: same-cycle NIRCam-NIRSpec/ MOS follow-up Submit combined proposal ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 17
JWST: same-cycle NIRCam-NIRSpec/ MOS follow-up Select targets Submit NIRCam and prepare combined images are NIRSpec MSA proposal acquired configurations Image constructed with Spitzer data, not a NIRCam simulation. ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 18
JWST: same-cycle NIRCam-NIRSpec/ MOS follow-up Select targets Submit NIRCam NIRSpec MOS and prepare combined images are spectroscopy NIRSpec MSA proposal acquired acquired configurations same JWST cycle Credit: ESA/ JWST SOT ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 19
JWST/ NIRSpec: parallel observations EXAMPLE PLAN FROM NIRSpec & NIRSpec in MOS-mode and NIRCam can be used NIRCam GTO programs simultaneously to observe adjacent fields JWST FIELD OF VIEW Credit: JWST User documentation (STScI) Courtesy of the NIRSpec and NIRCam GTO teams ESA UNCLASSIFIED – Releasable to the public Catarina Alves de Oliveira| 27/ 08/ 2019 | Slide 20
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