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2019 SB Gaia Sprint wrap-up

2019 SB Gaia Sprint wrap-up

Presented at the end of the 2019 Santa Barbara Gaia Sprint at the Kavli Institute for Theoretical Physics

David W Hogg

March 29, 2019
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Transcript

  1. 2019 SB Gaia Sprint
    Wrap-up — KITP — 2019-03-29

    View Slide

  2. Hans-Walter Rix (MPIA, Heidelberg)
    Learned many things, among them
    ● the small-scale structure of phase-space -- abundance space
    is strong and detectable -- Kamdar, Coronado
    ● the phase-space spiral twists, as it should -- Johnston
    ● wide-binary twins are real (& probably very useful) -- El-Badry
    ● GDR2 as a time-domain survey can and will be ``calibrated’’ -- Casey
    ● Gaia preselection of close, eclipsing binaries works perfectly -- Schwab
    Homework: help Anthony Brown find X MEuro to “do the selection function”

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  3. Ellianna Schwab Abrahams (UC Berkeley, CTDI)
    What Worked (Time Domain Gaia): What Didn’t Work (yet!):
    ● Measurements of flux RMS detect
    variability! Pulled lightcurves out of
    TESS for candidate variables confirming
    close eclipsing binaries, RR Lyrae and
    CVs. (With Mowlavi, Rix and Brown)
    ● Built a DSD neural net to predict RVs.
    RVs correlate enough with other features
    to predict within largest uncertainty (With
    Jamal, Hogg and Casey)
    ● Need to add Bayesian
    framework to
    improve network
    Cand.
    CV in both
    TESS + Gaia
    Alerts
    Thanks Rix, Brown, Casey,
    Hogg, Price-Whelan,
    Rimoldini, Brandt,
    Gaensicke & Gaia DPAC!

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  4. Alice Quillen (Rochester)
    I tried using current velocities and backwards orbits of moving groups,
    listed by Gagne+18 and with ages less than 60 Myr years, to see if the stars
    in them formed near spiral arms and find out where were the arms?
    Learned:
    Young moving groups seem
    associated with the “Local spur”.
    This arm may have wound up -- or
    two different armlets are required.
    Now 60 Myr ago
    Galactocentric
    Also Learned:
    -Ringing might have also been caused by a dwarf
    plunging through the center of the Galaxy.
    -VVV measuring proper motions in the bar’s X
    (resonant model for vertical heating?)
    Galactocentric angle degrees

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  5. Joel C. Zinn
    Ohio State University
    1. Responded to referee report on
    comparison of Gaia
    distances/radii to asteroseismic
    distances/radii!
    2. Learned about many cool things
    in discussions with people, e.g.:
    a. Halo is not relaxed (Quillen)
    b. White dwarf merger rates are
    consistent with Q branch
    number density… no Kozai?!
    (Cheng)
    c. Halo stars have unexpected
    abundance patterns (Matsuno)

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  6. View Slide

  7. Semyeong Oh (Cambridge)
    Linear velocity field of 40 m/s/pc
    may be detectable with
    astrometry + DR2 (statistical) noise
    + 30% RV (1 km/s uncertainty)
    for the Hyades cluster.
    Learned:
    ● important systematic bias for proper
    motions of bright sources
    ● T. Brandt’s Hipparcos-Gaia
    calibration removes this and
    reduces the precision by 5-10 for
    Hipparcos sources.

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  8. https://forms.gle/gEGuuPgpMz5rYA3E6

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  9. Christina Eilers
    Max Planck Institute for Astronomy
    ● blue and red patterns correspond to density fluctuations in
    the disk — spiral arms?
    ● quadrupolar velocity structure is seen in multiple models of
    the Galactic bar.
    ● vertical & radial velocity dispersions increase where we
    expect the bar to influence the stellar dynamics.
    Thanks to
    Sarah, Hogg,
    Ortwin,
    Chervin, Larry
    & Hans-Walter

    View Slide

  10. Sarah Pearson
    (Flatiron Institute, CCA)
    Compared the velocity tensor elements of
    Eilers’ & Hogg’s APOGEE/Gaia data to the
    velocity tensor elements of simulated bars
    I did this
    I learned
    SGR induced
    (C. Laporte)
    ….what we should
    expect to see in the
    various terms of the
    velocity tensor
    We see the bar in APOGEE/Gaia data and it looks
    similar to simulated bars
    [Will insert plots]
    Comparison to Eilers’ plots
    In situ
    (E. D’Onghia)
    with Eilers, Hogg, Laporte, D’Onghia, Rix
    and advise from Price-Whelan, Gerhard, Widrow

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  11. David W Hogg
    (NYU) (MPIA) (Flatiron)
    The radial-velocity variations we see (with APOGEE & Gaia) in the Milky Way disk
    are going to provide evidence for density variations.
    (Eilers, Pearson, Laporte)
    Related to this, I formulated a method to use disk simulations to build an
    empirical-theoretical model of disk patches.
    (Widrow)
    If we are seeing the bar at the Galactic Center, it is at the wrong angle!
    (Gerhard, Widrow, Pearson, Laporte, Rix)
    We need to sharpen up a proposal to build a set of Gaia selection functions.
    (Brown, Fouesneau, Rix, Casey, Price-Whelan)

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  12. Patrick LaChance
    (University of Wisconsin - Madison)
    What I did:
    Compare the contributions of different sectors of
    the U-V plot in different volumes to begin to
    disentangle moving groups from open clusters
    What I Learned:
    Getting to work on astronomy research all day is
    even better than I thought

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  13. Cosmological galaxies are not
    in an inertial frame
    Robyn Sanderson
    UPenn/Flatiron
    What I learned this week:
    Velocity of disk COM
    relative to halo COM
    Acceleration of COM calculated different ways
    X
    Y
    Z
    So….where
    are we
    building our
    models again?
    ….even when
    there’s no
    LMC...
    Position of disk COM
    relative to halo COM

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  14. theme of the week: diffuse disequilibrium
    (in science and life)
    Andrew Wetzel (UC Davis)
    ● Reconstruct gravitational potentials of MW-like
    galaxies/halos using Latte simulations (Sanderson,
    Vasiliev)
    ○ Initial analysis (see right) is a best case scenario:
    no M31, no LMC
    ○ Milky Way is not an inertial frame
    ● Use simulations to test effects of LMC on stellar halo
    (Cunningham, Sanderson)
    ● Use simulations + synthetic Gaia surveys to
    reconstruct 3-D dust distribution (Anderson)
    ● Public service notice: use cosmological Gaia mocks!
    (stolen from Sanderson)

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  15. Siddharth Mishra-Sharma (NYU)
    Learned:
    - How to perform Gaussian process regression on a sphere (with lots of help and code from Tim
    Brandt and Hamish Silverwood).
    - Code at https://github.com/smsharma/GPSphere (with Tim).
    Did:
    - Constructed model of the Gaia DR2 quasar proper motion field with GP regression.
    - Can use to characterize measurement systematics?
    - But not yet to look for substructure!
    - Used this method to construct un(??)biased power spectrum estimator.

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  16. Alexandra Borukhovetskaya(University of Wisconsin - Madison)
    undergraduate student working with Elena D’Onghia
    What I came to do:
    Learn Arcturus ages, metallicities, and
    clustering techniques.
    What I did:
    1. Found ages and metallicities for known
    members of Arcturus.
    2. Ran algorithm (SNN) with adjusted
    parameters to find several new
    candidate members.
    3. Compared ages and metallicities of
    candidate members to those of known
    members
    What I plan to do in the future:
    Continue modifying and improving the
    algorithm to find new members and gain insight
    into the origin of Arcturus.

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  17. Harshil Kamdar (Harvard)
    What I Did: finished writing up a paper on v wide (>10 pc)
    co-moving pairs due to disrupting star clusters in the disk, worked w/
    Coronado & Rix on interpreting small-scale structure in combined
    chemodynamical space (Gaia+LAMOST).
    What I Learned: sampling points to follow a correlation function is
    hard

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  18. Hamish Silverwood
    ICC University of Barcelona
    Failures:
    -Red Clump & Giants RVS samples corrected using cross
    match to 2MASS - thwarted at the last minute by a
    string encoding problem in Pandas.
    Successes:
    -GPflow & GPyTorch running in 2D with heteroskedastic
    noise (i.e. uncertainties - surprisingly non-trivial).
    -GPR on e.g. vRvR data (left) - needs work.
    -Derivatives of latent function f(x) with GPflow
    machinery (1D example above) - still quite rough, red
    line should match green line.

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  19. Anthony Brown (Leiden Observatory)
    What I did
    ● Struck gold!
    ○ Python notebook with example on how to create
    a 6D ‘Gold’ sample from Gaia DR2
    ○ https://github.com/agabrown/gaiadr2-6dgold-example
    ● Put my RUWE code on github
    ○ https://github.com/agabrown/gaiadr2-ruwe-tools
    ● Answered tons of questions on Gaia DR2
    select source_id, ra, ra_error, dec, dec_error, parallax, parallax_error,
    parallax_over_error, pmra,pmra_error, pmdec, pmdec_error, ra_dec_corr,
    ra_parallax_corr, ra_pmra_corr, ra_pmdec_corr, dec_parallax_corr,
    dec_pmra_corr, dec_pmdec_corr, parallax_pmra_corr, parallax_pmdec_corr,
    pmra_pmdec_corr, radial_velocity, radial_velocity_error,phot_g_mean_mag,
    phot_bp_mean_mag, phot_rp_mean_mag, bp_rp, g_rp, bp_g,
    2.5/log(10)*phot_g_mean_flux_over_error as phot_g_mean_mag_error,
    2.5/log(10)*phot_bp_mean_flux_over_error as phot_bp_mean_mag_error,
    2.5/log(10)*phot_rp_mean_flux_over_error as phot_rp_mean_mag_error,
    sqrt(astrometric_chi2_al/(astrometric_n_good_obs_al-5)) as uwe
    from gaiadr2.gaia_source
    where parallax_over_error>5
    and radial_velocity is not null
    and astrometric_params_solved=31
    and rv_nb_transits > 3
    Do some radial velocity cleaning...
    What I learned
    ● Phase spiral is not ‘just moving groups’
    ● Some of use do want to work on the selection function
    ○ Look for funding
    ● So many creative ways to use the Gaia data!

    View Slide

  20. Cecilia Mateu (UdelaR)
    What I Did+Learned:
    - Provided astropy reference
    frames for streams in galstreams
    library (+Adrian Price-Whelan)
    - Made galstreams Python 3
    compliant
    - Many RR Lyrae in Pal5's tails
    - Many streams are (very) difficult
    to confirm, but many (some?)
    do show up in PS1 photometry
    (w. Nora Shipp, A. P-W, Sarah
    Pearson, Giuliano Iorio)
    - Learned many cool astropy tools
    Homework:
    - Gaia RR Lyrae Gold!

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  21. Sukanya Chakrabarti (RIT)
    Worked on : what caused the disturbances in the outer HI disk of the Milky Way ?
    Sampling Gaia PMs

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  22. Zhen Yuan
    (Shanghai Astronomical Observatory)
    [email protected]
    Did:
    ● Got Member Probability of each star around
    Pal 5 from Photometry
    Sprint & Eugene Vasiliev (IoA, Cambridge)
    Thx for the advice from Nora, Adrian, David, and Giuliano !
    Motivation and Future Plans:
    1. Get tail members with 6D → Disruption Process
    2. Hunting for UFD
    You will see magic happens after combining probabilities from
    photometry & astrometry in Eugene’s slide!
    Learned:
    1. How to execute a project efficiently
    2. I need another PhD in Astronomy
    ● Happened to find Phase-Space
    Slices of Gaia Sausage using
    StarGO
    https://github.com/salamander14/StarGO
    Sprint & Tadafumi Matsuno (PhD student,
    NAOJ) and Kohei Hattori (U of Michigan)
    You will see what we can infer from the slices
    in Kohei’s slide!

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  23. Eugene Vasiliev (Institute of Astronomy, Cambridge)
    Search for tidal tails around globular clusters with Gaia astrometry and DECam photometry
    With Zhen Yuan and valuable advice from Adrian, Ana, Sarah P., Jason H., Nora, Giuliano
    Pal 5 NGC 288
    Learned Gaussian ProcessesⓇ, Matched FilteringTM.
    Developed the membership selection pipeline combining
    Gaussian Mixture for parallax+PM and Matched Filtering for CMD
    Re-discovered tails around Pal 5, NGC 288.
    Not found anything around NGC 5897, NGC 7089, …
    Plan to continue the search for other cluster tails...

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  24. Kohei Hattori (U of Michigan)
    phase-space slice of the Gaia Sausage
    With Tadafumi Matsuno (PhD student,
    NAOJ) and Zhen Yuan (SHAO).
    StarGO package (by Zhen Yuan) is
    powerful in finding substructure.
    Red: Solar neighbor / Black: total sample

    View Slide

  25. View Slide

  26. Elena D’Onghia (work with Boquan Chen)
    We use SNN algorithm (Chen et al. 2018) to cluster in 5 dimension to
    rebuild Orion. Two clumps are newly discovered.
    This approach opens us the possibility to study how star formation occurs
    in Orion.
    This is an example of the superiority of SNN on DBSCAN.
    (1) Two clusters one dense one less dense
    (2)-(3) DBSCAN recoves one group
    (4) SNN recovers both groups

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  27. Lorenzo Rimoldini (University of Geneva, CH)
    Classification of variable objects in all Gaia DR2
    (without time series):
    > better than you might expect
    >> it can be useful before DR3 (SDSS-V, TESS, ...)
    >>> help in gathering rare variable classes
    >>>> millions of new variable candidates soon!
    Learned about streams, complementary data sets,
    interesting color-color plots combining optical, IR
    and radio, features of AGBs in the radio band,
    some details about Gaia as well :)
    Please email me by the end of April if you want
    to make sure your class of interest is included!

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  28. Giuliano Iorio (Institute of Astronomy, Cambridge)
    ● Pal 5: 2 RRab, 4 RRc
    ● Stream: 16 RRab, 6 RRc
    Membership likelihood for RRLs in Pal 5 stream
    Thanks to Cecilia, Adrian, Nora, Eugene, Elianna
    for advice and useful discussions
    What I did:
    Learned: Galstreams, what is a GP, a
    lot of interesting way to use Gaia Data.
    What I found:
    A lof of RRLs!!
    To do: Improve background model,
    analyse other streams, Pal5 stream
    model.
    No other variables

    View Slide

  29. Larry Widrow
    Queen’s University
    Productive discussions on phase space spirals with Kathryn,
    Chervin … radially plunging satellites with Heidi, and GP blah blah
    blah with Lauren and Hamish, to be continued in Gaia “brisk walk”
    during and after the conference
    Gauthier, Dubinski, LMW 2006
    LMW, Chequers et al 2014
    Spekkens & Sellwood 2007
    With Hogg:
    Infer surface density
    from moments of the
    velocity field --- here,
    a linear model on
    pixels of simulation.
    Probably makes more
    sense to go after the
    FR , Fphi...learn rather
    than assume the
    Jeans/CBE (cf. Alice
    and Hamish)

    Var(Vphi)
    Density model residual

    View Slide

  30. Josh Simon
    Carnegie Observatories
    Thanks to:
    Lauren Anderson
    Anthony Brown
    Andy Casey
    Kohei Hattori
    Tadafumi Matsuno
    Zhen Yuan
    for helpful advice and questions
    Sample of 11475
    metal-poor MSTO
    candidates; ~50%
    complete and ~89%
    pure
    RGB selection is still
    in progress, but will
    have lower
    completeness (~25%)
    and purity (~67%)
    I learned: (1) It works!
    (2) How to cross-match on the Gaia Archive
    (3) The memory limit of my laptop
    I did:

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  31. Color code: amplitude of local
    corrections with respect to DR2.
    Some catalogs: no patterns
    Others: stripes along RA or Dec + large
    scale patterns.
    Banding due to old ground-based
    positions used to build proper motions.
    Larger scale patterns: reference system
    differences, or rotation.
    Ad e t in -bi g o
    as id r e r .
    TODO: apply to DR2 pm correction for rotation (Lindegren’s doc); check current results vs. astropy method
    for position propagation.
    Discovered this week: interesting intersections between dynamics in the Galaxy and the Solar System….
    Ideas for an article! ….Sprinting ! It works!

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  32. Juna Kollmeier (@ Doc right now unfortunately)
    GG Catalog Progress
    GG Brown Dwarfs: Faherty (Done)
    GG White Dwarfs: Gaensicke (Done)
    GG: CMD: Brown (Done)
    GG: 6D Phase Space: Brown (Done)
    Owners Needed:
    GG Globulars
    GG Spiral (Is there a spiral?)
    GG Local
    GG Red Clump (Hawkins?)
    GG RRL
    GG Low Z (Simon?)
    GG O/B
    Where to host these?

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  33. View Slide

  34. I’m Andy Casey (Monash) and this week I self-calibrated and simulated the
    astrometric and radial motion jitter for single stars (w/ Rix and Price-Whelan)
    the “binary fraction” simulated AEN
    - p.d.f. Of a source being a
    single star given
    astrometric/radial jitter
    (and colours/.mags)
    - radial velocity
    semi-amplitude for binary
    systems

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  35. Aim: 3d bulge kinematics from RVS


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  36. Newberg et al. (2007)

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  37. Nora Shipp
    m-M = 14 - 18.5
    [Fe/H] = -2
    Age = 12 Gyr
    Re-discovering &
    confirming stellar
    streams

    View Slide

  38. Alexa Villaume (University of California Santa Cruz)
    Observed color - Synthetic color
    Asked a lot of questions
    about sources of
    uncertainties and quality
    flags in DR2 (thank you
    Anthony and Morgan!)
    Learned:
    Quality flags
    are not
    always
    informative
    Learned: Apples-to-apples comparisons between
    synthetic and observed photometry is complicated
    and many corrections are needed

    View Slide

  39. Timothy Brandt, UCSB
    Kareem’s wide binaries can calibrate parallax uncertainties. Formal uncertainties
    are 20-30% underestimates? Only addresses spatially uncorrelated errors...
    Hints of magnitude-dependent zero-point offset (couple μas/mag)?

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  40. Emily Cunningham (UCSC)
    1. I worked with Sanderson and Wetzel on how we can quantify and measure the impact of an
    LMC-like interaction on the velocity field of a mostly accreted stellar halo.
    2. I estimated the parameters of the velocity ellipsoid over different octants in the sky using RR
    Lyrae! In the Milky Way (Pan-STARRS) and the Ananke mocks for the Latte simulations.
    Milky Way m12m: Latte/Ananke

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  41. w/ Cecilia Mateu: coordinate frames for stellar streams in galstreams
    → Next: we will clean up the library and provide other metadata for streams
    w/ Nora Shipp: what “known” streams in the north can be confirmed?
    → Next: compute significance for candidate rediscoveries, repeat with DECaLS?
    w/ Cecilia+Giuliano Iorio: RR Lyrae in the Pal 5 stream, >15 candidates
    → Next: fit stream models to new distance information, improve MSTO filter
    w/ Ana Bonaca: Improving models of the GD-1 stream
    1) How to use new RV measurements to improve fit of “spur”
    2) Better global models of the stream (Fail!)
    → Next: Figure out what is going on with the stream track?!
    Adrian Price-Whelan (Princeton)
    2D density model

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  42. P5. Astro
    Viz work! Thanks to
    Nora for data on
    Stream
    s!
    Movies forthcom
    ing

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  43. Luis Quiroga-Nuñez
    (Leiden Observatory/JIVE)
    VLA
    SiO maser emission
    No Coincidences in Gaia
    Coincidences in Gaia+2MASS (~400, %100 MIRA!)

    View Slide

  44. David Mykytyn, New York University
    ● Managed to learn a decent kernel density for the
    main sequence stars
    ● Very close (alas not close enough yet) to be able
    to generate the “binary sequence”
    ● Hopefully this will happen very soon?
    ● Learnt KDE in PCA space, and transformed it
    backwards into the real CM space

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  45. What I learned this week among other things
    ● Estimating Gaia’s small field of view correlations
    ● Wide-binary identical twins are real - good for parallax validation
    ● Effort to have Gaia selection function(s) [but will be painful to build]
    Morgan Fouesneau (MPIA, Heidelberg)
    What I did this week
    ● Dynamics of M31 HII regions using biased Gaia astrometry
    ● (incomplete) Empirical star cluster model
    Actually stars! Not looking at stars - epic fail!
    No coherent rotation
    Consistent with random
    Strongly doubting
    Van der Marel et al. 2019
    Something wrong
    with photometry
    pleiades

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  46. Jatan Buch(Brown U.)
    > Discussed:
    - Analytic modeling of disequilibria using the continuity equation with Larry and Hamish: can’t resolve all
    degeneracies, yet.
    - Accelerations for Hipparcos-DR2 x-matched stars (courtesy T. Brandt), definitely worth exploring!
    - Great breakout on simulations and mock catalogs. Got a flavor of the diversity of philosophies and techniques,
    going into the available codes, and, most importantly, their scope depending on the scientific problem at hand.
    > Worked on:
    - Responded to referee report for a paper on estimating the local DM content in the solar neighborhood; mild
    evidence of ‘excess’ matter density (also verified by A. Widmark using an independent technique).
    - Will better disequilibria modeling only improve precision and rule out the excess? Can only answer on a
    case-by-case basis.
    - Baby step: started simulating effect of DM halo (final goal: NFW population) + test particle disk on a stellar
    distribution using galpy potentials (thank you J. Hunt). [Bummed couldn’t make at least 1 pretty plot! :(]
    - Implemented A. Brown’s RUWE cut and found no significant change in derived results!

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  47. May Gade Pedersen
    (KU Leuven, Belgium)
    Johnston+2019
    Recreated from Bastian+2018
    Cordoni+2018
    Isochrone
    Cloud
    What I did:
    Constructed Gaia CMD of cluster with known
    eMSTO. Converted isochrone clouds to Gaia
    colours and ‘fit’ to observations.
    I learned
    Principles behind cluster membership
    verification. Use appropriate Gaia
    passbands for bolometric
    corrections.
    Cordoni+2018 Cordoni+2018

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  48. Kareem El-Badry (UC Berkeley)
    Twinning: excess of equal-mass
    wide binaries is real!
    Made a catalog of 3000
    hierarchical triples with
    RV-variable components
    Lots of other ideas:
    ● Companions to massive
    white dwarfs with Sihao
    Cheng
    ● Parallax error calibration
    with Timothy Brandt
    ● Calibrating
    gyrochronology with
    Jackie Faherty
    ● Kozai mechanism in
    triples with Juna
    Kollmeier
    Thanks for great discussions
    with Rix, Casey, Gaensicke,
    Oh, Hogg, Fouesneau, Brown,
    Kamdar ++
    Still working on the math ¯\_(ツ)_/¯

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  49. Jason Hunt (Dunlap/Toronto)
    Talked about: Non-axisymmetric structure, actions, galpy, phase space
    spirals, actual spirals, bars
    Worked on: Lots of little things, including
    paper draft from last sprint, and looked at
    models of different spiral structure
    Simulations from Alex Pettitt

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  50. Ana Bonaca (Harvard)
    Found GD-1 models with relative radial velocity
    offsets between the stream and the spur
    comparable to the observed offset

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  51. Lauren Anderson (Flatiron Institute):
    Worked on building a 3D dust map of the Milky Way
    Simulation: (Almost) reconstructed the “true” dust density in the Latte simulation,
    the foundation for Ananke. We have the right amplitudes and scales !!
    Data: Applied to 105 dust estimates from Gaia with good parallax estimates
    Hyper parameters: ℓ ~ 60 pc and σ ~ 80 M

    /pc3 (optimized from a more local sample)

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  52. Sihao Cheng Johns Hopkins University ● relation between the white dwarf Q branch
    and wide binary fraction with Kareem
    El-badry, supporting the idea of Q-branch
    WDs being WD-WD merger
    ● extinction within 250 pc is still uncertain
    ● tried to analyse proper motions of Sagittarius
    Stream bifurcation
    ● learned a lot. Some new ideas for my next
    possible project. Thanks for discussions with
    Newberg, El-badry, Anderson, Casey,
    Gänsicke, Zinn, Hunt, etc.

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  53. Borja Anguiano (University of Virginia)

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  54. Kathryn V Johnston (Columbia)
    ?? PS-Spirals - where? when? what??
    with Chervin Laporte and Larry Widrow
    Did: orbits in axisymmetric MW potential
    Learned:
    Jphi (=Lz!) => groups with shared history
    dvz & dvR “hit” => z-vz spirals & R-vr sloshing
    ???? Towards the ORIGIN ????:
    “Rewind” spiral in Jphi bins
    test approach with N-body sims
    limitations: impulsive assumption; local view; moving groups
    red: rguide =9 kpc white: rguide =7kpc

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  55. Chervin F. P. Laporte (UVic)
    PS-spirals (Larry, Kathryn, Anthony locally & Martin
    Cool Smith+Jason H+Jason S), finding the OLR with
    DR2 (Jason H), GP blablablah (Larry+Hamish),
    velocity field of MW (Eilers+Pearson+Hogg), Moving
    groups Arcturus (Elena D’Onghia)
    Did: checked some quick dirty solutions to my
    problems, didn’t work… but looking forward to next 3
    weeks :). Made this movie of the PS-spiral in
    overdensity to help you hypnotise your guests back
    home.
    Learned: I might have to GP blablablah my way out of
    this with RC to do what I initially intended to do.

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