Authors: Jonathan and Dr. Megan

We hope you enjoyed the April 8 eclipse and had a fun and safe viewing experience! Thanks to everyone who was able to join us for our eclipse live-stream event, hosted by Mike and Jon! If you were not on the path of the eclipse, or maybe the clouds were in your way that day, you can still see it from any angle in SpaceEngine (starting around J2460409.2 in the newly accepted Julian date format). We are also looking forward to hosting more events with our community in the future, so make sure you check out our Discord.

The ongoing refactoring process of our codebase still demands high commitment from our development team, but we are excited about this month’s update, which includes several bug fixes and a huge catalog update! The full list of updates is at the end of this blog post. In addition to a few dozen newly discovered exoplanets, around 800 new brown dwarfs, and two new stellar-mass black holes, we’re excited to share the extensive update of our stellar catalog: we have updated the spectral classifications and luminosity classes of more than 60,000 catalog stars and updated the distances to more than 100,000 catalog stars! And as hinted above, the date/time field on the Navigation toolbar now accepts input in Julian date format.

Continuing our recent showcase of exciting new exoplanets, the favorite pick this round is our newly discovered neighbor: TOI-715 b. Discovered by the Transiting Exoplanet Survey Satellite (TESS), this super-Earth is only 137 light years from our Solar System. TOI-715 b orbits within a conservative habitable zone around its cool, red host star, meaning it could potentially host liquid water! That's not to say TOI-715 b is a hospitable world; it is on a tidally locked orbit, so the same hemisphere always faces its host star, giving it a hot front-side and a cold back-side. TOI-715 b is 0.08 AU from its host star (closer than Mercury is to the Sun!), and its orbital period is only 19 days!

This may just be the beginning of the exciting news from the TOI-715 system, as it is suspected that another, smaller planet may also be present. If this second planet is confirmed, be sure to be on the lookout for its future appearance in SpaceEngine!

Also newly discovered in the neighborhood is a black hole called Gaia BH3! Gaia BH3 weighs about 33 times the mass of the sun, and is only 2000 light years from Earth. Since 2022, the space observatory Gaia has discovered three stellar-mass black holes called Gaia BH1, Gaia BH2, and Gaia BH3. The Gaia observatory found these black holes using a technique called astrometry, which precisely measures the positions of stars. Three stars Gaia looked at were found to wobble in their positions, and by studying the wobble, scientists concluded the gravitational pulls of unseen black holes were responsible. Using the properties of the wobbles, scientists are able to determine how much these black holes weigh. There are likely many more of these sneaky black holes lurking in our galaxy and throughout the universe, and we are excited to see what scientists find next! You may have even come across procedurally generated star-black hole systems in SpaceEngine that resemble Gaia BH1, 2 and 3!

In this image, gravitational lensing (the bending of spacetime around a massive object) bends the light of Gaia BH3's companion star, as well as the Milky Way galaxy behind it.

Gaia plays another big role in this month’s update, as precise measurements of position through astrometry allow scientists to determine distances by using a property called parallax. Parallax is the relative displacement between an object's position at different times, and using some simple trigonometry, distance can be calculated from parallax. Missions like ESA's Hipparcos space mission determined parallaxes and distances of stars in the past and now the more recent Gaia mission has refined those measurements and improved the accuracy significantly. We have updated more than 100,000 stars in SpaceEngine to use Gaia parallaxes and distances!

This plot shows the distances to stars in SpaceEngine before and after this update. We can see that smaller distances are fairly consistent both before and after this update, while larger distances are updated by Gaia data. We can even see evidence of rounding to a certain number of decimal points in the "old" data, in the horizontal line pattern in the data in the upper regions of the plot. The lack of vertical pattern tells us the newer data isn’t subject to this type of error to such a large extent. The data shown on the left and right panels is identical, but without and with logarithmic scaling of the axes. The plots contain over 100,000 data points.

That's not to say the older determinations of distances were wrong; Gaia's goal was to improve precision and make measurements for more objects. Of the more than 100,000 distances we updated in SpaceEngine, only 28,720 distances changed by more than 100 parsecs, and just 3,096 distances changed by more than 1,000 parsecs. Scientists are getting pretty good at measuring distances, and we’re finding new close-by things like TOI-715 b and Gaia BH3 nearby more and more frequently!

Further Reading:

TOI-715 b: NASA Press Release
Gaia BH3: ESA Press Release

BUILD 0.990.47.2015, CHANGES AND UPDATES FROM THE PREVIOUS VERSION:

• Added AgX tonemapping mode
• Added Gaia BH2 and BH3 black hole systems
• Updated rotation models for moons in our solar system to be more precise (DE436 model for Earth's moon, and IAU rotation for other moons in the Solar system) - Known issue: rotation begins to drift at the distant past or future (around the 20,000 year mark from the present)
• Date/time field on the Navigation toolbar now accepts input in Julian date format
• Added a new stellar limb darkening function (WIP)
• Updated spectral types for 60,000+ catalog stars
• Updated distances for 100,000+ catalog stars, as well as some black holes and their hosts (mostly minor, only a few thousand are more significant)
• Added 810 new brown dwarfs
• Added a few dozen new exoplanets/host stars
• Added some missing 'B' components of exoplanet-hosting binaries
• Updated naming conventions for some stars and nebulae
• Added an accretion disk to T CrB B (aka, The Blaze Star)
• Updated Uranus and Neptune's new moons, and tweaked their atmosphere colors to be more accurate
• Improved the appearance of Eris, Dysnomia, and Sedna
• Updated greenhouse gas concentrations in Earth's atmosphere
• Adjusted shadow and totality mask of the recent eclipse
• Tweaked atmosphere visuals for Galilean satellites
• Fixed Europa's classification/composition (it's a terra, not an aquaria)
• Updated albedo of Dione
• More climate model bug fixes, largely related to wind speeds
• Fixed eclipse shadow sizes being larger than they should
• Fixed carbon star spectral types for catalog planets always presenting as C-R
• Updated the asteroid (16) Psyche
• Fixed visibility distance of star cluster particles
• Removed flags from the language selection list
• Pruned duplicate catalog entries