Questions tagged [gaia]

Questions about the space observatory GAIA.

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41
votes
5answers
9k views

Why is Gaia operating around Earth orbit? Why not send it to Neptune's orbit?

Gaia is an astrometry spacecraft that's currently operating around the Sun-Earth L2 Lagrangian point. Question: why here? Why not the Sun-Neptune L2 Lagrangian point? By orbiting the Sun at a larger ...
14
votes
2answers
3k views

Why not send a Gaia-like mission to Mars?

This answer to the question why we didn't send Gaia to Neptune's orbit raises the question of why we don't send a Gaia-like mission to the orbit of Mars. It seems like it doesn't have the problems ...
9
votes
3answers
744 views

Why does Gaia use only calcium NIR lines for stellar radial velocity measurements?

I was reading this overview article about the Gaia spacecraft and I saw the following statement: These spectra provide radial velocity information that are used to study the kinematic and dynamic ...
9
votes
2answers
211 views

Is there an optimum orbit for a Hipparcos/Gaia-like parallax observatory

The Gaia spacecraft is currently mapping the stars in the Milky Way by parallax. It orbits in the Earth-Sun L2 Lagrange point. The parallax observed from the spacecraft orbiting around the sun allows ...
7
votes
4answers
2k views

What is the proper interpretation of a negative parallax?

The Gaia data release 2 dataset has some parallaxes listed as negative. What is the proper interpretation of this? Should they be discarded as bad data? Use their absolute value to calculate the ...
5
votes
1answer
133 views

What is the overlap between the Gaia and the Hipparcos catalog?

Is there any kind of concordance available between the sources in the Hipparcos catalog and the Gaia DR2 catalog? I.e., mapping the Gaia DR2 source_id to the Hipparcos HIP number?
5
votes
2answers
659 views

Did Gaia actually generate complete light curves for 212 Cepheids in other galaxies?

The recent BBC news item Gaia clocks speedy cosmic expansion says that a recent Gaia measurement of 212 Cepheid variables in other galaxies within the local group yields a Hubble constant of ~73 km/s/...
5
votes
1answer
568 views

Obtaining TESS input catalog (TIC) IDs for Gaia `source_ids`?

The TESS input catalog (TIC) "uses the GAIA DR2 catalog as a base" according to the catalog's website. The Gaia DR2 database provides source_ids for each ...
4
votes
1answer
285 views

Gaia Parallax data

When the Gaia parallax data (especially for Cepheid stars) become accessible to public? If it is already released for some parts, where can I find it?
4
votes
1answer
255 views

Why no Polaris distance in GAIA DR2?

Querying GAIA DR2 for Polaris (for example using https://gea.esac.esa.int/archive/) yields empty parallax columns. Anyone knows why it was not measured/published?
4
votes
1answer
344 views

Fits file re-alignment

I would like to re-align an image using a reference image (taken from GAIA). I am aware of the software Koords developed by the Karma team: https://www.atnf.csiro.au/computing/software/karma/ ...
4
votes
1answer
392 views

Very near GAIA DR2 sources - has Proxima Centauri been dethroned?

I made an extract of GAIA DR2 data for parallaxes greater than 500mas. Surprisingly I see a very significant number of sources with parallax greater that 1000, making them much closer than Proxima. ...
4
votes
1answer
253 views

Will Gaia detect inactive neutron stars?

Will the astrometric precision of the Gaia space telescope be able to detect the gravitational influence of cold old solitary neutron stars on the movements of stars? At least in a statistical sense ...
4
votes
1answer
105 views

Has GAIA learned anything about General Relativity looking near Jupiter? (Gerry Gilmore: "oblate rotating mass moving in a deeper (Solar) potential")

From Gerry Gilmore (2018) Gaia: 3-dimensional census of the Milky Way Galaxy 4.4 Fundamental physics Relativistic effects are highly significant for Gaia measurement accuracy, with tests of General ...
4
votes
1answer
459 views

Distance to Proxima Centauri (Gaia VS New Horizons parallax program)

The current best parallax measurement for the nearest star to the Solar System, Proxima Centauri, has been given by the European Space Agency's Gaia mission. This is $768.5004\; \pm \; 0.2030 \; mas$ (...
4
votes
1answer
234 views

How would a small TCO (temporarily captured orbiter) or other natural Earth satellite most likely be detected?

A sentence from the abstract of The population of natural Earth satellites states: At any given time there should be at least one NES of 1-meter diameter orbiting the Earth. The average temporarily-...
4
votes
2answers
259 views

Why (the heck) is the basic angle of GAIA 106.5°?

This answer to Why does the Gaia space telescope have two main mirrors says: According to the GAIA FAQs which does an excellent job: http://www.cosmos.esa.int/web/gaia/faqs: Why is there an angle of ...
3
votes
2answers
289 views

How can I calculate the uncertainties in magnitude like the CDS does?

When you check an entry of the Gaia DR2 stellar catalogue in Vizier, for example this one, you can see that there is a value for the G magnitude (in our case 18.0733 mag) and a value for the ...
3
votes
1answer
85 views

Approximate spectral type and luminosity given apparent magnitude and distance

I am looking at the data acquired from the Gaia DR2 survey. I found that most of the stars had their distance and apparent magnitude catalogued, but not their spectral type and luminosity class. Is ...
3
votes
1answer
985 views

Gaia Gbp - Grp: why does it get larger as star gets redder?

As an enthusiastic amateur scientist, I'm plowing my way through a cool Gaia DR2-based paper, "An Empirical Measurement of the Initial-Final Mass Relation with Gaia White Dwarfs". I'm doing all right, ...
3
votes
1answer
83 views

Is GAIA the only game in town for looking at quadrupole gravitational deflection of light?

From Gerry Gilmore (2018) Gaia: 3-dimensional census of the Milky Way Galaxy 4.4 Fundamental physics Relativistic effects are highly significant for Gaia measurement accuracy, with tests of General ...
3
votes
1answer
96 views

How do OGLE-III and GAIA measure the mass of free microlensing black holes?

What is the "hypothesized lower mass gap" between 2.5 and 5 solar masses? eventually links to Constraining the masses of microlensing black holes and the mass gap with Gaia DR2. The angle of ...
3
votes
0answers
57 views

Why is it hard to reconcile Gaia DR2 with the HIP data set

I'm trying to get a database of about 20 million of the brightest stars in the sky for a project I'm working on, and I want to reconcile it with the Hipparcos data set. Currently, I'm only using the ...
2
votes
3answers
1k views

Calculating the distance of objects using the Gaia DR1

The Gaia DR1 was released middle of September with ~1.1 billion objects. The schema contains right ascension, declination and parallax, which could be used to calculate Cartesian co-ordinates (xyz). ...
2
votes
2answers
168 views

How many GAIA Data Release 2 files are there?

I am using this index page to download GDR2 data files. http://cdn.gea.esac.esa.int/Gaia/gdr2/gaia_source/csv/ But it keeps giving a different number of links. Sometimes it shows 16,000 files, ...
2
votes
1answer
45 views

What was the first use of time-delay integration in Astronomy? Are there instances before GAIA?

In the context of GAIA, time-delay integration is the clocking of a CCD's charge shift register at a frequency such that it matches the linear speed across the focal plane of the actual image. So even ...
2
votes
1answer
69 views

How is interstellar gas density mapped from GAIA data?

I found the image below in Space.com's article This 3D Color Map of 1.7 Billion Stars in the Milky Way Is the Best Ever Made. The caption for this image reads: The Gaia spacecraft gathered ...
2
votes
1answer
67 views

What would "the next GAIA"-like instrument be like? Could it simply be a 3 to 5x scaled-up version of the same beautiful system?

This excellent, thorough and well-sourced answer to Has a gravitational microlensing event ever been predicted? If so, has it been observed? mentions several works where hundreds to thousands of ...
2
votes
1answer
63 views

How precisely we know the Gaia spacecraft baseline? [Question related to Planet 9 and the cosmic distance ladder]

The European Space Agency mission Gaia is performing an outstanding job by measuring the parallaxes of almost 2 billion stars, many of which are thousands of light years away from the Sun. For this ...
2
votes
1answer
56 views

What has GAIA found out about the dwarf galaxy heritage of stars in the Milky Way, if anything?

I ran across the image below in the August 2000 ESA Bulletin # 103 GAIA – Unravelling the Origin and Evolution of Our Galaxy Figure 3. This simulation shows how a galaxy halo, like our own, may ...
2
votes
0answers
127 views

How to calculate the various properties of a star?

I am wanting to plot a velocity profile (a plot of velocity against the star's distance from the galactic core) from the Gaia DR2, but so far my efforts have been disappointing. The information I ...
2
votes
0answers
190 views

Open cluster membership determination via parallaxes

I'm working in my final course project and I'm using the recently released GAIA DR2 data. I want to determine open clusters membership and I know this has mainly been done using proper motions and ...
2
votes
0answers
193 views

A question about using both the Simbad and the Gaia archive

It seems a bunch of people, including myself, have got it into our heads to create a 3D visualisation of the stars around us - one where you get to fly around them rather than view them from the ...
1
vote
1answer
198 views

How can GAIA's accuracy for position, parallax, and annual proper motion for a given star be the same number?

Per Wikipedia's Gaia (spacecraft); Objectives: Determine the position, parallax, and annual proper motion of 1 billion stars with an accuracy of about 20 microarcseconds (µas) at 15 mag, and 200 ...
1
vote
1answer
38 views

Extracting specific star data from Gaia DR2?

I would like to extract all Gaia DR2 sources which have six-parameter solutions as well as their radial velocities and effective temperatures. Is this possible as DR2 only specifies that there are 1,...
1
vote
1answer
120 views

What does correcting for LSR mean in galactic velocities?

This is a two-part question, but both parts are related: I'm aware that modern astronomical software can correct velocities for the local standard of rest (LSR), but what does that really mean? As in,...
1
vote
0answers
12 views

Did Gaia DR3 help figure out whether Albireo is an optical double?

Based on the Wikipedia page of Albireo, Gaia DR2 had too much noise to determine whether the stars are physically associated or if they are just an optical double. Gaia DR3 was released last year. ...
1
vote
0answers
27 views

Relationships between G magnitude, Johnson V magnitude, and spectral type of stars?

I'm simulating a population of binary stars for a summer research project. I'm adding uncertainties to my simulated observables such as angular position and radial (line of sight) velocity. I'm using ...
1
vote
0answers
27 views

How to explain tidal tails and dark matter sub-halos in simple terms?

There is the exciting news by ESA entitled Is the nearest star cluster to the Sun being destroyed? Data from ESA’s Gaia star mapping satellite have revealed tantalising evidence that the nearest ...
1
vote
0answers
111 views

Plotting GAIA barycentric radial velocity data with python

Does anybody know of a good tutorial on how to use python and astropy to generate plots of GAIA, RAVE or any other database of barycentric (heliocentric) radial velocity data of stars in our galaxy? ...
1
vote
0answers
54 views

What a grating on GAIA RVS spectroscope?

What size of the grating on GAIA RVS spectroscope ? How many lines on mm, or what defraction angle for 850 nm wavelenth light ? I find some more details here: http://sci.esa.int/gaia/44092-gaia-rvs-...
1
vote
0answers
171 views

Photometry data from Gaia

I am trying to get data from Gaia. Especially for Cepheids or RR Lyrae. On Gaia websites it say they have released some of the data however I cannot find it. I am looking for two columns with time and ...
0
votes
1answer
57 views

Query with Gaia: I have a list of 1000+ source_id's. How do I find the associated stars and their data?

I have a table of around 1700 source id's from gaiadr2 (in csv format). I would like to see the data that Gaia has for each star in a new table. I'm really struggling to figure out how to do this ...
0
votes
1answer
139 views

How to convert Proper Motion in RA & Dec to Galactic Coordinates

I'm trying to parse stellar data in the GAIA 2 release to galactic coordinates and am struggling with the velocity component. I've tried following online documentation and papers, but end up with ...
0
votes
0answers
52 views

Why can't ESA/NASA build a handful of Gaia telescopes and launch them into different positions in space for better accuracy?

I've noticed that many stars in GAIA DR2 have highly uncertain distances. Why can't a space agency send multiple Gaia spacecraft into orbit around different places (One in L2 Earth, one in ...