ESA - Gaia updates

[AegeanBlue]

Gaia's living and breathing Milky Way



This is very interesting in its own right though it has a technical issue the first two minutes. What I also want to point out is something buried in the end: Gaia is expected to run out of cold gas for its thrusters between January and March 2025

[deadman1204]

Gaia's living and breathing Milky Way



This is very interesting in its own right though it has a technical issue the first two minutes. What I also want to point out is something buried in the end: Gaia is expected to run out of cold gas for its thrusters between January and March 2025

Its easy to forget that they have only analyzed the first 34 months of data! They expect DR5 (final) one in 2030

[bolun]

Gaia discovers a new family of black holes

Using data from ESA’s Gaia mission, astronomers have discovered not only the closest but also the second closest black hole to Earth. The black holes, Gaia BH1 and Gaia BH2, are respectively located just 1560 light-years away from us in the direction of the constellation Ophiuchus and 3800 light-years away in the constellation Centaurus. In galactic terms, these black holes reside in our cosmic backyard.

The two black holes were discovered by studying the movement of their companion stars. A strange ‘wobble’ in the movement of the stars on the sky indicated that they are orbiting a very massive object. In both cases, the objects are approximately ten times more massive than our Sun. Other explanations for these massive companions, like double-star systems, were ruled out since they do not seem to emit any light.

Image credit: ESA/Gaia/DPAC

[AegeanBlue]

We are three weeks away from GaiaFPR, which is a preview of DR4. There was a series of sessions at the European Astronomical Society meeting in Krakow about Gaia and some presentations have been posted here:

https://great.ast.cam.ac.uk/Greatwiki/GreatMeet-PM16

A few standouts:

For Ω Centauri GaiaDr3 has something like 50,000 stars. The FPR will have over half a million new sources with those in DR3 purposely excluded. This is a test of the new full frame method for crowded regions. When the scan line saturated from too many stars, the spacecraft was programmed to simply take a picture of the whole frame. In the earlier data releases they had not process the whole sky images. For Focused Product Release they are showing the results of their new processing chain starting with Ω Cen

FPR actually has fewer solar system objects than DR3. However they have improved their processing chain, used the 66 months and thus have superior quality of observations. DR4 will have 350,000 objects as opposed to the 156,000 objects in FPR and 158,000 objects in DR3

GaiaNIR, the successor, will not be launched until 20 years after the end of Gaia on purpose: they want the astrometric baseline. So even if everything is funded and developed on time, I would guess it would wait on the ground for its time.

DR4 will be the largest astronomic catalog ever and it will surpass the Hubble Fine Guidance Sensor catalog which I think currently has the crown. Nothing is said about DR5, but I would assume that after the spacecraft dies a new full reprocessing of the data will have with all Gaia data. DR4 is for 66 months which is the original mission plan but the spacecraft is still alive and gathering data.

[Star One]

New Gaia release reveals rare lenses, cluster cores and unforeseen science

Today, ESA's Gaia mission releases a goldmine of knowledge about our galaxy and beyond. Among other findings, the star surveyor surpasses its planned potential to reveal half a million new and faint stars in a massive cluster, identify over 380 possible cosmic lenses, and pinpoint the positions of more than 150 000 asteroids within the Solar System.

https://www.esa.int/Science_Exploration/Space_Science/Gaia/New_Gaia_release_reveals_rare_lenses_cluster_cores_and_unforeseen_science

All the papers are linked to in the press release above.

[AegeanBlue]

There was a press conference that came with this release. It was partially recorded and put here:



The first session that apparently was from Timo Prusti that gave a general overview was not recorded, it starts midway in the second about Omega Centauri. In DR3 at the center of Ω Centauri there is a hole. Using the engineering camera they set up a new methodology and now have half a million plus stars there on high resolution. It is not as good as the normal process for reasons they explain but it is better than the current hole. They also mention that they will follow the same technique for another 8 crowded areas of the sky. I do have a question that was not asked or answered (there was no Q&A session): I know that for the next Data Release they use the previous release as the ingestion catalog. Are these new stars going to be in the ingestion catalog for DR4? My guess would be no because while for Ω Centauri the data is out now 2 years before DR4, that may not be true for the other 8 regions. I guess we need to wait for DR5

Interstellar Dust (I could be getting the order of the presentations wrong). They used the spectra of the stars that are far from the dusty galactic plain as pure endmembers and using the same stellar classes they mapped something like 2,000,000 voxels of the Milky Way for dust. They also put extracted some new information about the diffuse interstellar bands but no actual solution as to what molecules cause them. They did show some 2D visualizations, the 3D one at the end did not work. You could see though the spiral arms of the galaxy, or at least I thought I did

Pulsating Stars: They started from the over a billion stars of the Gaia catalog and after several quality selections they ended up with some 10,000 pure samples that are binaries. The pulsation is due to the rotation and how it effects both the other star and the gas and dust between them. New stellar astrophysics information came out of this analysis

Gravitational Lenses: Gaia was never planned for this task, it emerged from the science community using its data. They begin with the quasar catalog of DR3 which is the largest quasar catalog and search for nearby objects. 87% of quasars are lonely, but the rest have nearby companions, including 100,000 objects that are not in DR3 (quality flags?). They they used classification with known doublets and quadruplets to find something similar in the 500,000 nearby objects, which is too many to do by hand. The 381 objects may not seem much, but for quadruplet it is something like 60% more that are known and for doublets 130% more (I write from memory, I can be wrong). Now they have applied at giant earth based telescopes for spectroscopic measurements of these 381 because they are mostly too faint for Gaia spectroscopy. We will see how many get confirmed

The last presentation was about the asteroids. As a mentioned in an earlier post they are fewer objects than in DR3. However because they have now 66 months of observation they are 2 orders of magnitude or in layman's terms 100 times better in terms of accuracy than DR3 for the main asteroid belt. You see 66 months is good enough to have seen whole orbits for the main belt leading that better accuracy. For Jupiter Trojans though they do not have a full orbit so it si only 2 to 5 times more accurate than DR3. They also wet our appetites for DR4. They will have far more objects including for the first time comets near their perihelion. They compared their orbital parameters with the JPL catalog as validation, the JPL catalog has far more years of observation than Gaia. For the first 50,000 numbered objects orbit difference is on the average 1 km (yes, that good) and the spread looked quite random and tight on the chart. They mentioned how they had 42 million observation which they same submitted to the Minor Planet Center which has under 200 million observations of minor planets overall since Ceres discovery on January 1 1801.

If you have the time, it is worth watching

[FutureSpaceTourist]

https://twitter.com/esascience/status/1737033914537885892

🥳🎂 @ESAGaia celebrates its tenth anniversary since launch🚀
👇Let’s look at the #GaiaMission in numbers

2/ What have we learned about our galaxy in this decade of research?

⚖️ how to weigh our galaxy
🌀 what our galaxy looks like
💥 which collisions took place with other dwarf galaxies

Find out more 👉 https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_s_decade_of_discoveries_unravelling_the_intricacies_of_our_galaxy

https://twitter.com/esascience/status/1737033923404689596

3. Have a look around our Milky Way in this high-resolution interactive image by @ESAGaia
👉 https://www.esa.int/ESA_Multimedia/Images/2020/12/Interactive_map_of_the_sky_from_Gaia_s_Early_Data_Release_3

[AegeanBlue]

ESA had three press releases today about the 10 year launch anniversary of Gaia

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_s_decade_of_discoveries_unravelling_the_intricacies_of_our_galaxy

Mostly a write up of what is on the previous post

https://www.esa.int/ESA_Multimedia/Images/2023/12/Gaia_s_10th_anniversary

The post above in summary

https://www.esa.int/ESA_Multimedia/Videos/2023/12/Galactic_Chloe_-_the_Gaia_mission

Galactic Chloe is apparently a Swiss I would guess social media influencer - science popularizer. 12 minute video in English

[AegeanBlue]

New quasar catalog from Gaia. This is the ESA press release

https://www.esa.int/ESA_Multimedia/Images/2024/03/Gaia_maps_largest_ever_collection_of_quasars_in_space_and_time

Also there is article on Universetoday. I think the name of the catalog is Quaia

[AegeanBlue]

Lecture: Shiva & Shakti star sub-structures identified in Gaia DR3 [IIT Hyderabad]



I was wondering why those stellar streams did not get names from Greek mythology, now I know. Also there have been several articles incorporating Gaia results, such as this one from Universetoday

https://www.universetoday.com/167516/do-we-now-have-an-accurate-map-of-nearby-stars/

Spoilers: no, we are missing something like 15-20% of nearby stars despite the new ones identified by Gaia. I have been posting sporadically here but generally something like two general audience articles per week incorporate a study with findings from Gaia even if the mission's name is not on the article title

[Targeteer]

https://www.esa.int/Enabling_Support/Operations/Double_trouble_Gaia_hit_by_micrometeoroid_and_solar_storm

Double trouble: Gaia hit by micrometeoroid and solar storm
17/07/2024 344 views 7 likes
ESA / Enabling & Support / Operations

Launched in December 2013, ESA’s Gaia spacecraft is on a mission to map the locations and motions of more than a billion stars in the Milky Way with extreme precision.

But it’s not easy being a satellite: space is a dangerous place. In recent months, hyper-velocity space dust and the strongest solar storm in 20 years have threatened Gaia’s ability to carry out the precise measurements for which it is famous.

In April, a tiny particle smaller than a grain of sand struck Gaia at high speed. Known as a micrometeoroid, millions of these particles burn up in Earth’s atmosphere every day.

But Gaia is located 1.5 million km from Earth at the second Sun-Earth Lagrange point (L2). Out here, far from our planet’s protective atmosphere, Gaia is often struck by particles like this. Impacts are expected, and the spacecraft was designed to withstand them.

This object, however, struck Gaia at a very high speed and at just the wrong angle, damaging the spacecraft’s protective cover.

The impact created a little gap that allowed stray sunlight – around one billionth of the intensity of direct sunlight felt on Earth – to occasionally disrupt Gaia’s very sensitive sensors.

Gaia’s engineers were in the middle of dealing with this issue when they were faced with another problem.

The spacecraft’s ‘billion-pixel camera’ relies on a series of 106 charge coupled devices (CCDs) – sensors that convert light into electrical signals.

In May, the electronics controlling one of these CCDs failed – Gaia’s first CCD issue in more than 10 years in space. Each sensor has a different role, and the affected sensor was vital for Gaia’s ability to confirm the detection of stars. Without this sensor to validate its observations, Gaia began to register thousands of false detections.

The root cause for the electronics failure is not entirely clear. Gaia was designed to spend up to six years in space but has now survived almost twice as long under harsh conditions.

Around the time of failure, Gaia was hit by the same violent burst of energetic particles from the Sun that triggered spectacular auroral lightshows around the world.

The spacecraft was built to withstand radiation, but during the current period of high solar activity, it is being pushed to its limits.

It is possible that the storm was the final straw for this piece of the spacecraft’s aging hardware.

The Gaia teams at ESA’s ESOC operations centre, ESTEC technology centre and ESAC astronomy centre, together with experts from the spacecraft’s manufacturer, Airbus Defence and Space, and the payload experts of the Data Processing and Analysis Consortium, have worked together closely over the past few months to investigate, analyse and, ultimately, solve these problems.

“Gaia typically sends over 25 gigabytes of data to Earth every day, but this amount would be much, much higher if the spacecraft’s onboard software didn’t eliminate false star detections first."

"Both recent incidents disrupted this process. As a result, the spacecraft began generating a huge number of false detections that overwhelmed our systems,” explains Edmund Serpell, Gaia spacecraft operations engineer at ESOC.

“We cannot physically repair the spacecraft from 1.5 million km away. However, by carefully modifying the threshold at which Gaia’s software identifies a faint point of light as a star, we have been able to dramatically reduce the number of false detections generated by both the straylight and CCD issues.”

Thanks to the hard work and efficient collaboration of all the teams involved, Gaia was recently returned to routine operations.

In fact, the engineers took the opportunity of this unscheduled disturbance to refocus the optics of Gaia’s twin telescopes for the final time. As a result, Gaia is now producing some of the best quality data that it ever has.

[jacqmans]

Gaia spots possible moons around hundreds of asteroids
08/08/2024

ESA’s star-surveying Gaia mission has again proven to be a formidable asteroid explorer, spotting potential moons around more than 350 asteroids not known to have a companion.

Previously, Gaia had explored asteroids known to have moons — so-called ‘binary asteroids’ — and confirmed that the telltale signs of these tiny moons show up in the telescope’s ultra-accurate astrometric data. But this new finding proves that Gaia can conduct ‘blind’ searches to discover completely new candidates, too.

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_spots_possible_moons_around_hundreds_of_asteroids#msdynmkt_trackingcontext=84d4fe00-6511-4df6-bb5e-f37880728860

[bolun]

Gaia spots possible moons around hundreds of asteroids

Image credit: ESA

[AegeanBlue]

In early July Gaia had a science meeting. The presentations are here:

https://great.ast.cam.ac.uk/Greatwiki/GreatMeet-PM17

Per the presentations Gaia was supposed to end the mission in January 2025 due to lack of consumables, even before the hit by the meteoroid and solar flare

[LouScheffer]

In early July Gaia had a science meeting. The presentations are here:

https://great.ast.cam.ac.uk/Greatwiki/GreatMeet-PM17

Per the presentations Gaia was supposed to end the mission in January 2025 due to lack of consumables, even before the hit by the meteoroid and solar flare

This archive is great!  Too often after conferences, all that is left is a collection of abstracts.  Saving the slides is a huge improvement. 

[hoku]

More details on the planned end of science ops on Jan 15, 2025, technology tests, and Gaia's final disposal into a heliocentric orbit:

"The Gaia spacecraft relies on a cold gas propellant to keep it spinning and scanning the sky. The amount of remaining cold gas decreases by about a dozen grams per day and is reaching its end in early 2025. The Gaia science observations will therefore end on 15 January 2025, meaning that no more nominal science data will be acquired by Gaia after that date."

https://www.cosmos.esa.int/web/gaia/end-of-observations

edit: PDFs of web pages attached

[deadman1204]

More details on the planned end of science ops on Jan 15, 2025, technology tests, and Gaia's final disposal into a heliocentric orbit:

"The Gaia spacecraft relies on a cold gas propellant to keep it spinning and scanning the sky. The amount of remaining cold gas decreases by about a dozen grams per day and is reaching its end in early 2025. The Gaia science observations will therefore end on 15 January 2025, meaning that no more nominal science data will be acquired by Gaia after that date."

https://www.cosmos.esa.int/web/gaia/end-of-observations

Bleh, the site is down for the next 24 hours

[hoku]

Farewell to Gaia - a final calibration image has been obtained on the binary star 61 Cygni.

"Gaia's observation programme came to an end today, on 15 January 2025, after ten and a half years of regular sky scanning, netting all the way more than 2600 billion astrometric observations. The measurement of the parallaxes of at least one billion stars was one of the major objectives of the mission at selection time. The results so far published in Gaia's second and third data release amply confirm the success in fulfilling this ambitious promise.

Among the iconic stars in the Gaia harvest, the most symbolic regarding the core of the mission is 61 Cygni whose distance was the first ever measured in 1838 thanks to the perseverance and skills of F. W. Bessel. It happens that this was also the last iconic star observed in the Gaia programme, just a couple of days before the science observations were terminated. This is a good opportunity to recall the great achievement of Bessel and to show the unprecedented leap brought in this field by ESA's space astrometry missions: Hipparcos and Gaia.

The special Gaia function was activated during the recent passages of 61 Cygni to acquire the image in Figure 1 and to pay tribute to all who spent time at the eyepiece of a telescope or a measuring machine to probe the depth of the starry world. They paved the way to Hipparcos and Gaia. (...)"

https://www.cosmos.esa.int/web/gaia/iow_20250115

[deadman1204]

A singularly amazing mission. Its interesting how ESA doesn't do the "biggest peice of glass" shiny missions, but do amazing things like this which while not as sexy as jwst are just as important as it is

[bolun]

Sky-scanning complete for Gaia

ESA’s Milky Way-mapper Gaia has completed the sky-scanning phase of its mission, racking up more than three trillion observations of about two billion stars and other objects over the last decade to revolutionise our view of our home galaxy and cosmic neighbourhood.

Launched on 19 December 2013, Gaia’s fuel tank is now approaching empty – it uses about a dozen grams of cold gas per day to keep it spinning with pinpoint precision: this amounts to 55 kg of cold gas for 15 300 spacecraft ‘pirouettes’.

Gaia’s catalogue is ever-growing, containing data on stars and other cosmic objects such as asteroids in our Solar System, exoplanets, binary stars and other galaxies.

After the raw data are downlinked to Earth, ESA and the Gaia Data Processing and Analysis consortium prepare the data for scientific use, adding crucial information for their usage.

Since the publication of the first Gaia data in 2016 and counting up to early 2025, Gaia’s catalogue has been accessed more than 580 million times, resulting in the publication of over 13 000 scientific papers.

This is far from the end of the mission, two massive data releases are still to come.

Related article: Last starlight for ground-breaking Gaia

https://www.esa.int/ESA_Multimedia/Images/2025/01/Sky-scanning_complete_for_Gaia

Image credit: ESA/Gaia/DPAC, Milky Way impression by Stefan Payne-Wardenaar