Monday, January 6, 2014
AAS 223: Monday, January 6.
105.01 Geoff Marcy: Masses and Radii of 42 small exoplanets
Large number of 1-4 R_E planets, previously unexpected as they are not seen in our solar system.
High resolution spectroscopy and astroseismology on target stars, constrain stellar properties.
22 KOIs, 42 transiting planets
Keck spectroscopy to measure/place limits on masses
Kepler 406b, new rocky planet: M=4.71 +/- 1.7 density = 9.18 g/cc
Kepler 94b: 10.84 +/-1.4, density 1.45 g/cc
Plot mass/radius: see small planets (less than 2 R_E) dominantly rocky. Appears to be radius cutoff for super-earths/mini-Neptunes. (http://arxiv.org/pdf/1312.0936v2.pdf)
Kind of jumped into the middle of 103.01: Megan Schwamb: Planet Hunters: Kepler By Eye
General talk about the benefits of crowdsourcing Kepler data (seems to be a dissertation talk).
Recovery rate between 80-90% for planets for to 4 Earth radii, much lower (40% for 2-3 Earth Radii)
Unexpected finds found through Planet Hunters Talk: allows volunteers to discuss odd light curves
Transiting planet around eclipsing binary, fat chance finding them with automated routines (paraphrased)
PH1 b (link) first confirmed planet from Planet Hunters
System is a 4-star, with 2 made of 2 close binaries
Planet is 6.2 R_E, M < .5 M_J
Wang et al. 2013: giant planet candidates in HZ, ~6 missed by Kepler, and a few with only 2 transits. (http://arxiv.org/pdf/1301.0644.pdf)
Interesting stellar finds as well, RR Lyrae, cataclysmic variables, etc
7 planet candidate system: See Joey Schmitt's poster
103.02 Fabienne Bastien: Photometric Flicker
Stars are noisy, gets in the way of photometric signals. Typically, we look for the lowest-noise stars to analyze. Try to use stellar noise to better characterize stars.
Use long cadence data to characterize Sun-like (F, G, K) stars
"crackle" - number of zero-crossings. Low "crackle" = longer term variability
"flicker" - measure of short term (>8 hour) variability
Flicker traces surface gravity. (http://arxiv.org/ftp/arxiv/papers/1308/1308.4728.pdf)
Comparison between astroseismic- and flicker-measured surface gravities is very favorable.
Also observed flicker from the Sun. Solar flicker is largely invariant
Absence of spots related to higher flicker?
Radial velocity jitter can be predicted from measured photometric flicker: comparison of photometric data to RV measurements from the California Planet Search
F-stars are very noisy, high radial velocity jitter. Again, flicker seems to trace RV jitter, but sample is small.
119 Plenary Session -Alyssa Goodman: Linking Visualization and Understanding in Astronomy
Fun note: powerpoint slides had to be printed on 35-mm film back in 1996... at the same time Geoff Marcy was announcing his exoplanet discoveries.
Computers suck at pattern recognition and creativity, but are good at calculations... and that's pretty much it.
Plug for Worldwide Telescope with respect to Galileo's observations from Siderius Nuncius. Free software, downloading now.
Example of Big Data visualization: Milky Way Project - humans' pattern recognition abilities feeding into machine learning.
Wide data - multiple data sets obtained from different methods (like having IR, visible, and radio observations of a single source).
Unsolved problem: Big AND Wide Data.
Visualized as a cube
1D - columns (like spectra, SEDs, or time series)
2D - faces or slices (like images)
3D - volume visualization, sometimes difficult to do in astronomy, and with 2D screens.
4D - time evolution of the above. Our brains are pretty bad at this.
Goodman 2009 (Nature) published a 3D interactive image in pdf. This is really fucking cool. (Of course, Nature's behind a fucking paywall so I can't link you to the paper. Because gods forbid people have ACCESS to science. Seriously, fuck Nature.) ApJ apparently able to accept such figures. (Tutorial by Josh Peek available here)
Uploading astronomical image to flickr and tagging astrometry group finds the image on the sky and view it in other wavelengths and such.
ADS all sky survey plans to connect all images of the same objects/regions (adsass.org)
Glue - Python program for linked datasets. (glueviz.org/en/latest/)
D3PO - allows Glue-made plots and such to be manipulated online (d3po.org)
Authorea - publishes such figures online (authorea.org)
Microsoft Kinect can be used to interact with Worldwide Telescope (I REALLY WANT TO TRY THIS!)
Whole bunch of links to cool interactive demos that I need to get off a handout. Will type up when I can.
Kepler/K2 Town Hall
Surprise! The longer Kepler goes, the more small planets we find. Of course, we're not getting any more of the usual data from Kepler, so we just have to analyze it.
2014: HUGE growth in Earth-size and slightly above Earth-size planets (78% increase in Earth/super-Earth size and 33% growth in Super-Earth/mini-Neptune sizes).
Remaining tasks with Quarter 1-12 data
- finalize planet candidates vs false positives and such
- update stellar parameters (temp, surface gravity, metallicity)
- update ephemerides (period, epoch)
- new planetary parameters
- finish catalog paper (Rowe et al. in prep)
Q1-Q16 catalog in prep (Mullally et al)
Will look at all quarters of data AND review all previous KOIs.
Kepler is in close-out stage. Over the next 3 years, this will involve...
- improving the pipeline further
- uniformly processing all data to put up on MAST by June 2014
- generate Q1-Q17 catalog (100% complete catalog)
- increase sensitivity to small planets by improving photometry
Community participation encouraged. Kepler Science center (keplerscience.arc.nasa.gov)
K2 - Kepler's Second Mission
Kepler only has 2 reaction wheels left, so pointing is significantly less precise, but can still be used. 42 white papers submitted within a month.
Ecliptic plane pointing can balance out many different high-impact science goals
- observe 4-6 fields per year
- new science from enabled by variety of galactic locations
- observe ~10,000 community-selected targets per field
- still use long and short cadence
- NO EXCLUSIVE DATA PERIOD!
Will still observe exoplanet transits. Target low-mass stars. Expected 4000 M dwarfs/field, can find HZ planets around these stars (short orbital periods). Bright stars also possible; can provide early targets for TESS, CHEOPS and JWST.
Lowest temp stars allow good sensitivity to Earth-radius planets with 2 orbits (in an 80ish day period).
25% of Kepler planets have < 8 day periods, most of which are small.
Star clusters and star forming regions (ecliptic has a lot of sweet star clusters
- more exoplanet detection!
- Stellar activity and rotation: angular momentum evolution, pre-main sequence and young stars
- eclipsing binaries in clusters (nice to observe low-mass young eclipsing binaries
- astroseismology to explore stellar structure across the H-R diagram
- Accretion, circumbinary disks, gas flows, protoplanetary disks
Extragalactic science with Kepler
- AGN variability
- Supernova light curves + progenitors (pre-SN light curves observed), allows you to learn about the progenitor and study shock break-out.
- could perform microlens parallax measurement. Measure microlensing event both in space and from the ground!
- be entirely guest observer mission, very largely community driven. Limited to 75-80 days per field per 2 years. Each K2 campaign will be "stand-alone" for science value.
- use solar pressure to balance remaining reaction wheels to keep pointing. Limits view to the ecliptic.
- undergo 80 day performance demonstration in March 2014, possibility of collecting light curves from 5,000-10,000 targets
Son of a bitch. Nothing from the afternoon session auto-saved because my battery died. There was some good stuff there too, including a planet whose orbital period is shorter than the Return of the King Blu-Ray edition and meeting the author of "Winter is Coming" (http://arxiv.org/pdf/1304.0445.pdf) talking about circumbinary planets. Now I'm mad. Apparently this only autosaves in draft form. God damn it.