Source-linked AI summary
The Exoplanet Orbit Database II: Updates to exoplanets.org
Eunkyu Han, Sharon X. Wang, Jason T. Wright, Y. Katherina Feng, Ming Zhao, Jacob I. Brown, Colin Hancock
TL;DR
The paper addresses the need to keep tracking exoplanet discoveries and to better catalog orbital parameters and host-star properties. It describes updates to the EOD and EDE, including broader planet and host-star coverage and new data fields, while noting that reported upper limits are not defined consistently across studies.
Problem
The project aims to keep track of exoplanet discoveries and better catalog orbital parameters and host-star properties.
Method
The authors maintain and update the EOD and EDE by broadening included host stars and discovery methods, adding fields, and documenting revised database categories.
Results
The updated resources include robustly detected planets around diverse host stars and from additional discovery methods, secondary eclipse depths, heterogeneous mass estimates, and Kepler planet candidates.
Takeaways & Limitations
These updates make exoplanets.org more complete for confirmed exoplanets and provide users with broader data for plotting and exploring planetary systems.
Takeaways & Limitations
Upper limits are not defined consistently across the literature, so users are encouraged to consult the original references for interpretation.
Abstract
from arXiv · showhide
The Exoplanet Orbit Database (EOD) compiles orbital, transit, host star, and other parameters of robustly detected exoplanets reported in the peer-reviewed literature. The EOD can be navigated through the Exoplanet Data Explorer (EDE) Plotter and Table, available on the World Wide Web at exoplanets.org. The EOD contains data for 1492 confirmed exoplanets as of July 2014. The EOD descends from a table in Butler et al. (2002) and the Catalog of Nearby Exoplanets (Butler et al. 2006), and the first complete documentation for the EOD and the EDE was presented in Wright et al. (2011). In this work, we describe our work since then. We have expanded the scope of the EOD to include secondary eclipse parameters, asymmetric uncertainties, and expanded the EDE to include the sample of over 3000 Kepler Objects of Interest (KOIs), and other real planets without good orbital parameters (such as many of those detected by microlensing and imaging). Users can download the latest version of the entire EOD as a single comma separated value file from the front page of exoplanets.org.
1. Introduction
The paper documents ongoing maintenance and expansion of the Exoplanet Orbit Database and Exoplanet Data Explorer as exoplanet discoveries and available data have rapidly increased.
- Exoplanet data growth: Over 1490 confirmed exoplanets and more than 3000 Kepler Objects of Interest were available by July 2014.Kepler contributed more than 800 confirmed discoveries, while the transit method surpassed radial velocity as the most fruitful detection method.
- Database purpose: The authors continue maintaining the EOD and EDE to track discoveries and catalog orbital parameters and host-star properties.
- Database scope: The EOD focuses on robustly detected exoplanets with well-determined orbital parameters from peer-reviewed literature, complementing other online compendia.Related databases provide complementary coverage and cross-checking.
- User access: The EDE provides interactive tables and plotting tools, while the complete exoplanets.org dataset can be downloaded as one CSV file.
- Use: The EOD is widely used in exoplanet research, and exoplanets.org recorded over 47,000 visits in 2013.The visit count is measured using Google Analytics.
- Updates: Since earlier documentation, the EOD and EDE expanded to include additional host-star types, parameters, and Kepler candidates, alongside major website back-end changes.
2. Updates on the EOD
The EOD broadened its inclusion criteria and reorganized its fields to represent discoveries, systems, and planets across more detection methods while retaining quality requirements.
- Scope: The EOD now includes robustly detected planets around any host-star type and discovered by methods including timing and imaging, not only radial velocity and transit.Examples include pulsar planets and β Pictoris b.
- Selection criteria: The database retains requirements for robust detections and well-determined orbits, although these judgments are sometimes subjective.The authors may remove a planet if later evidence reduces confidence, even when that evidence is not peer reviewed.
- Field organization: The EOD documents newly added and revised fields, with field descriptions organized by categories corresponding to individual planet pages.The fields also apply to all planets on exoplanets.org and are available in the downloadable CSV file.
- Discovery and references: Discovery reporting now separates the discovery method of an individual planet from that of its planetary system.The fields support RV, Transit, Imaging, Microlensing, Timing, and Astrometry values.
- Discovery and references: The KEPID field stores the integer identifier assigned to a Kepler host star and is available for unconfirmed KOIs imported from the Exoplanet Archive.
- Discovery and references: KOI identifiers encode a Kepler host star and candidate planet, with decimal suffixes distinguishing multiple candidates around one star.For example, KOI 102.01 and KOI 102.02 denote inner and outer candidates.
- Database flags: The EOD Boolean records whether a planet has well-characterized orbital parameters, distinguishing EOD planets from other exoplanets.org entries.Planets outside the EOD have EOD set to FALSE.
2.2. Orbital Parameters
The updated orbital fields accommodate measurements from different detection methods and provide common mass and separation quantities for plotting heterogeneous planet samples.
- Orbital measurements: Orbital parameters describe planetary orbit shape, with radial velocity typically supplying K and transit observations typically supplying inclination i.Planet-planet interactions and astrometry can also constrain inclination.
- Mass: MASS reports a planet’s mass in Jupiter masses using literature values, combined measurements, or MSINI when inclination is unknown.The database marks the MSINI fallback in MASSREF.
- Mass: For transiting Kepler planets lacking measured MSINI, the database estimates mass from literature mass-radius relations for plotting.The relations are combined across radius ranges, including a smooth transition between overlapping relations.
- Mass: Masses estimated from mass-radius relations are identified in the MASSREF field.
- Separation: SEP records host-star–planet separation in AU, using projected separation for directly imaged and microlensing planets or A when separation is unavailable.When SEP is set to A, SEPREF records that substitution.
- Additional orbital fields: The updated database includes inclination constraints for some non-transiting systems, while BIGOM is currently listed only for β Pictoris b.LAMBDA records projected spin-orbit misalignment and is available for transiting systems.
- Field revisions: MASSREF and MASSURL now refer to planetary mass, while MSTARREF and MSTARURL refer to stellar mass.
2.3. Transit Parameters
The EOD added transit-related fields for Kepler Objects of Interest and specifies how transit geometry and radius ratios are represented or derived.
- KOI fields: Two new fields were added for KOIs imported from the Exoplanet Archive.
- Transit geometry: DR records the planet–star distance during transit in stellar radii and contributes to transit light-curve modeling.
- Transit geometry: RR records the planetary-to-stellar radius ratio; if DEPTH is unavailable, the database calculates it as RR squared.The reverse calculation from DEPTH to RR is not performed.
2.4. Secondary Eclipse
The EOD added secondary-eclipse depth fields because measurements across multiple wavelength bands had become available for many planets. It also records whether any such measurement exists for a system.
- New secondary-eclipse depth fields were added as multi-band measurements became available for many planets.These fields extend the EOD beyond its earlier coverage of secondary-eclipse data.
- SEDEPTH fields record eclipse depths in 2MASS, Kepler, and Spitzer IRAC wavelength bands.The bands include J, H, KS, KP, 3.6, 4.5, 5.8, and 8.0 µm.
- The SE Boolean indicates whether a system has at least one secondary-eclipse measurement in the EOD.
2.5. Stellar Properties
The stellar-properties parameters provide physical properties of exoplanet host stars, with many values derived from stellar models in the literature. The section defines velocity, radius, and density fields.
- Stellar-property parameters describe physical properties of exoplanet host stars and generally derive from literature stellar models.The EOD provides references for these parameters.
- GAMMA is the center-of-mass radial velocity of the planetary system relative to the barycentric frame, reported in km/s.It is typically less precise than K because it requires an absolute velocity measurement.
- RSTAR is the host-star radius in solar units.
- RHOSTAR is the host-star density in g/cm3.
2.6. Stellar Magnitudes
The EOD reports host-star brightness in optical, 2MASS, and Kepler filters, while also adding distance and standardized uncertainty fields for stellar and orbital quantities.
- Host-star brightness is reported through V, B−V, 2MASS J, H, Ks, and the added Kepler KP magnitude.Definitions of V and B vary in the literature and are often based on Hipparcos magnitudes.
- DIST was added as host-star distance in pc, with distance and parallax calculated from each other when only one is reported.For stars with Hipparcos numbers and no reported distance or parallax, parallax is obtained from van Leeuwen (2009).
- XUPPER and XLOWER store upper and lower 1σ uncertainties, while UX stores their average, (XUPPER + XLOWER)/2.These fields cover orbital, transit, secondary-eclipse, stellar-property, DIST, and PAR parameters.
2.10. Removed Fields
Two fields were removed or replaced in the updated EOD. SPTYPE was dropped because it was difficult to verify and poorly maintained, while NSTEDID was replaced by EANAME.
- 2 fields were removed since Wright et al. (2011).
- SPTYPE was removed because host-star types were difficult to verify from peer-reviewed references and the field was not well maintained.Users are encouraged to use TEFF and BMV instead.
- NSTEDID was replaced by EANAME, the host-star name used by NASA’s Exoplanet Archive.
3. Inclusion of the Kepler Planet Candidates and Other Exoplanets on exoplanets.org
The EDE now includes Kepler planet candidates and robustly detected planets from imaging, microlensing, and timing, while distinguishing objects without well-determined orbits as “Other Planets.”
- Kepler Planet Candidates: KOIs are included in the EDE for context alongside confirmed exoplanets, although their candidate status excludes them from the EOD.KOIs with dispositions other than “FALSE POSITIVE” are included.
- Kepler Planet Candidates: The EDE uses broad SEP and MASS definitions so KOIs can be compared with EOD planets despite having few strictly defined parameters in common.
- Other Exoplanets: Robustly detected imaging, microlensing, and timing planets are now included under stated detection criteria.The criteria include mass ratio, separation, confident detection, and confident binding requirements.
- Other Exoplanets: Microlensing planets are accepted when refereed literature reports unambiguously planetary masses, while timing planets require dynamically stable orbits and ideally multiple complete orbits.
- Other Exoplanets: Planets lacking well-determined orbital parameters appear as “Other Planets” rather than in the EOD.As of July 2014, no microlensing or imaging planets except β Pictoris appeared in the EOD, while several timing planets did.
4. Updates to the Website software
The website software retains its existing architecture while switching the backend to Ruby and optimizing the JavaScript frontend for larger Kepler-era datasets.
- Software Stack: The backend server is now written in Ruby, but its role remains largely unchanged from the previous software stack.
- Software Stack: The JavaScript frontend now renders only on-screen table cells to support larger datasets from the Kepler missions.
- User Tools: Users can save plot parameters with browser cookies so updated data can reproduce customized plots.
- User Tools: Tables can be generated and exported with custom computed fields.
- User Tools: Plots can be exported at varied resolutions and aspect ratios, including publication-quality SVG graphics.
5. Summary and Future Work
The updates broaden the EOD’s coverage and make exoplanets with poorly characterized orbits available on exoplanets.org, while future work targets richer visualization and explicit handling of upper limits.
- Summary: The EOD now includes planets around non-normal stars, discoveries from additional methods, secondary eclipse depths, and broad SEP and MASS fields.
- Summary: KOIs and other planets without well-characterized orbits are reported on exoplanets.org for statistical studies and comparison, though they are excluded from the EOD.
- Future Work: Planned website additions include images of directly imaged planets, transit and microlensing light curves, RV curves, and improved incorporation of Kepler parameters.
- Future Work: The authors plan to report literature upper limits for MSINI, ECC, and K when available, with future table, plot, filter, and query support.Because authors define upper limits differently, users are encouraged to consult the original references.