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View Full Version : Second Gaia data release is tomorrow, 25 Apr 2018



selden
2018-Apr-24, 01:07 PM
The second Gaia data release is scheduled to happen at Noon CEST tomorrow, 25 Apr 2018.

It'll include positions for 1,692,919,135 stars.

Information about Gaia is available at http://sci.esa.int/gaia/
and about DR2 at https://www.cosmos.esa.int/web/gaia/dr2

According to the DR2 Media Kit, which is available at http://sci.esa.int/gaia/60174-media-kit-for-gaia-data-release-2/


The press event about the Gaia Data Release 2 is being organised by ESA at
the ILA Berlin Air and Space Show in Germany on Wednesday 25 April 2018,
11:00–12:15 CEST.

The event will be streamed live at: http://www.esa.int/live

peteshimmon
2018-Apr-24, 02:42 PM
I expect there will be many previously uncharted white dwarf stars within a hundred lightyears of us. And many may be coincident with long GRBs where the optical picture had no "credible" optical transient. Just a few field stars!

StupendousMan
2018-Apr-25, 11:40 PM
I recommend the article "Gaia Data Release 2. Observational Hertzsprung-Russell diagrams" available at

https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/201832843

More HR diagrams that you've seen in one paper in your entire life -- and they are all so very, very accurate and precise! Our journal club had a ton of fun with them today.

If you can't access the paper directly (it should appear on arXiv within a week, I would guess), you can see at least one of those beautiful HR diagrams at

https://www.esa.int/spaceinimages/Images/2018/04/Gaia_s_Hertzsprung-Russell_diagram

ngc3314
2018-Apr-26, 02:11 AM
Meanwhile, someone from the RECONS team just posted that they will have a talk tomorrow at the STScI symposium (streamed and recorded) showing that the false-positive rate for a simple GAIA DR2 query on objects closer than 10 pc is very high. I'm thinking the culprits unresolved binaries with periods in the right range to spoof parallax/orbit separation over the current time span, since the position-shift values themselves are so high above the measurement uncertainties..

StupendousMan
2018-Apr-26, 11:54 AM
Hmmm. Same sort of effect that is blamed for the most promising Dyson Sphere candidate in this paper ...

https://arxiv.org/abs/1804.08351

Jean Tate
2018-Apr-27, 08:13 PM
Such a treasure trove!

I didnít see anything on supernoavae; surely some were observed?

Why those limits on Teff?

More MW satellites and streams in DR3? Maybe even M31 and M33?

Jean Tate
2018-Apr-30, 09:31 PM
Such a treasure trove!

<snip>

More MW satellites and streams in DR3? Maybe even M31 and M33?
Nope: "Gaia Proper Motions and Orbits of the Ultra-Faint Milky Way Satellites" (arXiv:1804.10230 (https://arxiv.org/abs/1804.10230)), dated 26 April 2018! :)

Maybe it'll be DR3 for M31 and M33 ;)

ngc3314
2018-May-03, 01:39 PM
Maybe it'll be DR3 for M31 and M33 ;)

At that point we'll feel the clammy, procedural correct hand of the ghost of Adriaan van Maanen.

Jean Tate
2018-May-04, 12:48 PM
At that point we'll feel the clammy, procedural correct hand of the ghost of Adriaan van Maanen.
OMG! :eek:

I had to look him up; here's WP: Adriaan van Maanen (https://en.wikipedia.org/wiki/Adriaan_van_Maanen)

In other news, Gaia DR2 keeps on giving, for MW satellites etc:

"The Missing Satellites of the Magellanic Clouds? Gaia Proper Motions of the Recently Discovered Ultra-Faint Galaxies", Kallivayalil+ (2018) (astro-ph link (https://arxiv.org/abs/1805.01448))

"Gaia DR2 Proper Motions of Dwarf Galaxies within 420 kpc: Orbits, Milky Way Mass, Tidal Influences, Planar Alignments, and Group Infall", Fritz+ (2018) (astro-ph link (https://arxiv.org/abs/1805.00908))

Jerry
2018-May-08, 02:00 AM
OMG! :eek:

I had to look him up; here's WP: Adriaan van Maanen (https://en.wikipedia.org/wiki/Adriaan_van_Maanen)
"This does not, however, explain supposedly corroborating findings from Mount Wilson, Lowell Observatory, Russia, and the Netherlands."
:)

kzb
2018-May-14, 04:31 PM
First Gaia Dynamics of the Andromeda System: DR2 Proper Motions, Orbits, and Rotation of M31 and M33

https://arxiv.org/abs/1805.04079

This paper finds that the motion of Andromeda relative to the Milky Way is "more radial" than thought.

it says the merger will still happen, but the encounter pericentre radius is increased from 31kpc to 75kpc and it is put off from 3.9 to 5.5 billion years in the future.

It seems to me the larger encounter distance (75 kpc) means the main stellar disks will miss each other. Perhaps only the outer regions will be affected?

kzb
2018-May-18, 11:26 AM
Watched the BBC Sky at Night special on GAIA last night. There are some fantastic visuals produced from GAIA data.

Apparently there are stars orbiting in the wrong direction in the galaxy, that is they are orbiting in the other direction than the bulk of the other stars. Didn't know that one !

StupendousMan
2018-May-18, 01:17 PM
Would those stars happen to be the remnants of smaller galaxies which were long ago swallowed by the Milky Way?

kzb
2018-May-21, 02:02 PM
Would those stars happen to be the remnants of smaller galaxies which were long ago swallowed by the Milky Way?

Yes that was what they were saying. The stars were described as moving "head on" to us, but I am not sure if that is over dramatic.

I would guess the reason these stars have not been spotted up to now is because they are a fair distance from us?

glappkaeft
2018-May-21, 02:59 PM
Yes that was what they were saying. The stars were described as moving "head on" to us, but I am not sure if that is over dramatic.

I would guess the reason these stars have not been spotted up to now is because they are a fair distance from us?

Stars with retrograde motion and stellar streams from remnants of swallowed galaxies have been knows for quite some time. For these stars in particular it could be any combination of apparent brightness (distance is not a hard limit in astronomy) or simply the much greater coverage of Gaia compared with earlier studies.

ETA: Distance could however have an effect if these stars are within the distance Gaia can do parallax measurements but older studies couldn't.