Image of the Week

Mapping and visualising Gaia DR2

 

Figure 1: Map of the Milky Way within 3000 parsec of Earth as created by Galaxy Map / Kevin Jardine (webversion of this map allowing some interaction with the map is available here, and a downloadable file with the poster is available here). Image credit: Galaxy Map / Kevin Jardine.

How do you display a map of a billion stars? Astronomers have been mapping the sky for thousands of years but the unprecedented nature of Gaia DR2 presents new challenges, both in the scale of the dataset and its three-dimensional (3D) nature.

The solution showcased in the image above utilizes density isosurfaces, a technique more commonly used in industry (for example by the oil industry to model gas flows or by medical technicians to extract bone or other tissue images from MRI scans). This 3D map was developed by Kevin Jardine of Galaxy Map by first extracting the 72 million low error stars with error/parallax smaller than 0.1, and then selecting the 400 thousand stars from this set with negative colour index within 3000 parsec. This selection allows to select mostly OB stars which are young and largely located in associations, typically close to the Galactic plane.

This data set was converted into a scalar field by Gaussian smoothing the number of stars per cubic parsec and rendered into three-dimensional density meshes using the marching cubes algorithm. The mesh regions were then coloured based upon the number of Gaia DR2 stars with ionizing colours (colour index < -0.2) they contained: purple (>= 10  Gaia DR2 ionizing stars), light blue (between 4 and 10 Gaia DR2 ionizing stars) and dark blue (<= 4 Gaia DR2 ionizing stars).

Also plotted on this map are a selection of ionizing stars as shown with dots on the map. These seem to line up largely with the isosurfaces shown. The gray shading behind parts of the map is intended to highlight the assumed inner and outer parts of the galaxy.

The techniques and input data used to create this map are based on the following:

Given that non refereed articles were used to produce this map, this map should be considered as a pure visualisation of Gaia DR2 data and not as a scientific product.

To make this map available with the Gaia Sky visualisation software, Kevin Jardine collaborated with Toni Sagrista, developer of Gaia Sky. Gaia Sky is a real-time, three-dimensional, astronomy visualisation software capable of visualising Gaia data. It was used to create some of the videos used at the Gaia Data Release 2 press event.

A new version of Gaia Sky is now available and this new Gaia Sky 2.0.1 incorporates some improvements which make it more interesting and exciting to explore the Gaia data with.

Figure 2: Same selection as in Figure 1 available in Gaia Sky, visualisation software for exploring Gaia data. (Image source: Gaia Sky, acknowledgement: Toni Sagrista)

First of all, the set of isosurfaces in Gaia Sky was updated to include dust maps, HII regions and hot star density isosurfaces of very ionizing, some ionizing and non-ionizing regions, all derived from Gaia DR2 data. This provides further context to explore our part of the Galaxy. In order to enable the meshes, one can click on 'Meshes' in the 'Visibility' pane or use the keyboard shortcut L_CTRL+H. Use the 'Objects' pane to control what specific meshes are rendered and also to get some description of what each mesh represents.

 

 

Second, the distribution of stars into our levels-of-detail structure was greatly improved to provide a smoother and pop-in free navigation and traversal of the catalogue. New catalogue files need to be downloaded from the official site to take advantage of this. Of course, the updated version of the default catalogue is already bundled with the application.

Some other treats that made it into this new release of Gaia Sky are amongst others the ability to see and export system logs directly from within Gaia Sky, the addition of an FPS limiter and improved, shader-based grid rendering.

 

Credits: ESA/Gaia/DPAC, Gaia Sky / T. Sagrista, Galaxy Map / K. Jardine (twitter: @galaxy_map)

[Published: 13/06/2018]

 

Image of the Week Archive

2018
18/12: Gaia captures a rare FU Ori outburst
12/12: Changes in the DPAC Executive
26/11:New Very Low Mass dwarfs in Gaia data
19/11: Hypervelocity White Dwarfs in Gaia data
15/11: Hunting evolved carbon stars with Gaia RP spectra
13/11: Gaia catches the movement of the tiny galaxies surrounding the Milky Way
06/11: Secrets of the "wild duck" cluster revealed
12/10: 25 years since the initial GAIA proposal
09/10: 3rd Gaia DPAC Consortium Meeting
30/09: A new panoramic sky map of the Milky Way's Stellar Streams
25/09: Plausible home stars for interstellar object 'Oumuamua
11/09: Impressions from the IAU General Assembly
30/06: Asteroids in Gaia Data
14/06: Mapping and visualising Gaia DR2

25/04: In-depth stories on Gaia DR2

14/04: Gaia tops one trillion observations
16/03: Gaia DR2 Passbands
27/02: Triton observation campaign
11/02: Gaia Women In Science
29/01: Following-up on Gaia
2017
19/12: 4th launch anniversary
24/11: Gaia-GOSA service
27/10: German Gaia stamp in the making
19/10: Hertzsprung-russell diagram using Gaia DR1
05/10: Updated prediction to the Triton occultation campaign
04/10: 1:1 Gaia model arrives at ESAC
31/08: Close stellar encounters from the first Gaia data release
16/08: Preliminary view of the Gaia sky in colour
07/07: Chariklo stellar occultation follow-up
24/04: Gaia reveals the composition of asteroids
20/04: Extra-galactic observations with Gaia
10/04: How faint are the faintest Gaia stars?
24/03: Pulsating stars to study Galactic structures
09/02: Known exoplanetary transits in Gaia data
31/01: Successful second DPAC Consortium Meeting
2016
23/12: Interactive and statistical visualisation of Gaia DR1 with vaex
16/12: Standard uncertainties for the photometric data (in GDR1)
25/11: Signature of the rotation of the galactic bar uncovered
15/11: Successful first DR1 Workshop
27/10: Microlensing Follow-Up
21/10: Asteroid Occultation
16/09: First DR1 results
14/09: Pluto Stellar Occultation
15/06: Happy Birthday, DPAC!
10/06: 1000th run of the Initial Data Treatment system
04/05: Complementing Gaia observations of the densest sky regions
22/04: A window to Gaia - the focal plane
05/04: Hipparcos interactive data access tool
24/03: Gaia spots a sunspot
29/02: Gaia sees exploding stars next door
11/02: A new heart for the Gaia Object Generator
04/02: Searching for solar siblings with Gaia
28/01: Globular cluster colour-magnitude diagrams
21/01: Gaia resolving power estimated with Pluto and Charon
12/01: 100th First-Look Weekly Report
06/01: Gaia intersects a Perseid meteoroid
2015
18/12: Tales of two clusters retold by Gaia
11/11: Lunar transit temperature plots
06/11: Gaia's sensors scan a lunar transit
03/11: Celebrity comet spotted among Gaia's stars
09/10: The SB2 stars as seen by Gaia's RVS
02/10: The colour of Gaia's eyes
24/09: Estimating distances from parallaxes
18/09: Gaia orbit reconstruction
31/07: Asteroids all around
17/07: Gaia satellite and amateur astronomers spot one in a billion star
03/07: Counting stars with Gaia
01/07: Avionics Model test bench arrives at ESOC
28/05: Short period/faint magnitude Cepheids in the Large Magellanic Cloud
19/05: Visualising Gaia Photometric Science Alerts
09/04: Gaia honours Einstein by observing his cross
02/04: 1 April - First Look Scientists play practical joke
05/03: RR Lyrae stars in the Large Magellanic Cloud as seen by Gaia
26/02: First Gaia BP/RP deblended spectra
19/02: 13 months of GBOT Gaia observations
12/02: Added Value Interface Portal for Gaia
04/02: Gaia's potential for the discovery of circumbinary planets
26/01: DIBs in three hot stars as seen by Gaia's RVS
15/01: The Tycho-Gaia Astrometric Solution
06/01: Close encounters of the stellar kind
2014
12/12: Gaia detects microlensing event
05/12: Cat's Eye Nebula as seen by Gaia
01/12: BFOSC observation of Gaia at L2
24/11: Gaia spectra of six stars
13/11: Omega Centauri as seen by Gaia
02/10: RVS Data Processing
12/09: Gaia discovers first supernova
04/08: Gaia flag arrives at ESAC
29/07: Gaia handover
15/07: Eclipsing binaries
03/07: Asteroids at the "photo finish"
19/06: Calibration image III - Messier 51
05/06: First Gaia BP/RP and RVS spectra
02/06: Sky coverage of Gaia during commissioning
03/04: Gaia source detection
21/02: Sky-background false detections in the sky mapper
14/02: Gaia calibration images II
06/02: Gaia calibration image I
28/01: Gaia telescope light path
17/01: First star shines for Gaia
14/01: Radiation Campaign #4
06/01: Asteroid detection by Gaia
2013
17/12: Gaia in the gantry
12/12: The sky in G magnitude
05/12: Pre-launch release of spectrophotometric standard stars
28/11: From one to one billion pixels
21/11: The Hipparcos all-sky map
15/10: Gaia Sunshield Deployment Test
08/10: Initial Gaia Source List
17/09: CU1 Operations Workshop
11/09: Apsis
26/08: Gaia arrival in French Guiana
20/08: Gaia cartoons
11/07: Model Soyuz Fregat video
01/07: Acoustic Testing
21/06: SOVT
03/06: CU4 meeting #15
04/04: DPCC (CNES) 
26/03: Gaia artist impression 
11/02: Gaia payload testing  
04/01: Space flyby with Gaia-like data
2012
10/12: DPAC OR#2. Testing with Planck
05/11: Galaxy detection with Gaia
09/10: Plot of part of the GUMS-10 catalogue
23/07: "Gaia" meets at Gaia
29/06: The Sky as seen by Gaia
31/05: Panorama of BAM clean room
29/03: GREAT school results
12/03: Scanning-law movie
21/02: Astrometric microlensing and Gaia
03/02: BAM with PMTS
12/01: FPA with all the CCDs and WFSs
2011
14/12: Deployable sunshield
10/11: Earth Trojan search
21/10: First Soyuz liftoff from the French Guiana
20/09: Fast 2D image reconstruction algorithm
05/09: RVS OMA
10/08: 3D distribution of the Gaia catalogue
13/07: Dynamical Attitude Model
22/06: Gaia's view of open clusters
27/05: Accuracy of the stellar transverse velocity
13/05: Vibration test of BAM mirrors
18/04: L. Lindegren, Dr. Honoris Causa of the Observatory of Paris
19/01: Detectability of stars close to Jupiter
05/01: Delivery of the WFS flight models
2010
21/12: The 100th member of CU3
17/11: Nano-JASMINE and AGIS
27/10: Eclipsing binary light curves fitted with DPAC code
13/10: Gaia broad band photometry
28/09: Measuring stellar parameters and interstellar extinction
14/09: M1 mirror
27/08: Quest for the Sun's siblings
 
Please note: Entries from the period 2003-2010 are available in this PDF document.