Author Topic: ESA - Gaia updates  (Read 51867 times)

Offline Star One

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Re: ESA - Gaia updates
« Reply #100 on: 02/15/2017 07:05 PM »
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[Toronto] Using a novel method and data from the Gaia space telescope, astronomers from the University of Toronto have estimated that the speed of the Sun as it orbits the centre of the Milky Way Galaxy is approximately 240 kilometres per second.
In turn, they have used that result to calculate that the Sun is approximately 7.9 kiloparsecs from the Galaxy’s centre—or almost twenty-six thousand light-years.

Using data from the Gaia space telescope and the RAdial Velocity Experiment (RAVE) survey, Jason Hunt and his colleagues determined the velocities of over 200,000 stars relative to the Sun. Hunt is a Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics, University of Toronto.

http://www.dunlap.utoronto.ca/missing-stars-in-the-solar-neighbourhood-reveal-the-suns-speed-and-distance-to-the-centre-of-the-milky-way-galaxy/

Offline Star One

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Re: ESA - Gaia updates
« Reply #101 on: 03/06/2017 07:53 PM »
Gaia Data Release 1. Open cluster astrometry: performance, limitations, and future prospects

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Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs.

https://arxiv.org/abs/1703.01131

Offline bolun

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Re: ESA - Gaia updates
« Reply #102 on: 04/13/2017 12:23 PM »
Two million stars on the move

12 April 2017

The changing face of our Galaxy is revealed in a new video from ESA’s Gaia mission. The motion of two million stars is traced 5 million years into the future using data from the Tycho-Gaia Astrometric Solution, one of the products of the first Gaia data release. This provides a preview of the stellar motions that will be revealed in Gaia's future data releases, which will enable scientists to investigate the formation history of our Galaxy.

http://sci.esa.int/gaia/59004-two-million-stars-on-the-move/


Offline bolun

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Re: ESA - Gaia updates
« Reply #103 on: 06/10/2017 12:51 PM »
The future of the Orion constellation

9 June 2017

A new video, based on measurements by ESA’s Gaia and Hipparcos satellites, shows how our view of the Orion constellation will evolve over the next 450 000 years.

Stars are not motionless in the sky: their positions change continuously as they move through our Galaxy, the Milky Way. These motions, too slow to be appreciated with the naked eye over a human lifetime, can be captured by high-precision observations like those performed by ESA’s billion-star surveyor, Gaia.

By measuring their current movements, we can reconstruct the past trajectories of stars through the Milky Way to study the origins of our Galaxy, and even estimate stellar paths millions of years into the future.

This video provides us with a glimpse over the coming 450 000 years, showing the expected evolution of a familiar patch of the sky, featuring the constellation of Orion, the Hunter.

http://www.esa.int/Our_Activities/Space_Science/Gaia/The_future_of_the_Orion_constellation


Offline Ben the Space Brit

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Re: ESA - Gaia updates
« Reply #104 on: 06/11/2017 04:31 PM »
That Orion one has one major bit of speculation in it: No-one knows how long Betelgeuse has left!
"Oops! I left the silly thing in reverse!" - Duck Dodgers

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Offline Star One

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ESA - Gaia updates
« Reply #105 on: 07/08/2017 08:54 PM »
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With the help of software that mimics a human brain, ESA's Gaia satellite spotted six stars zipping at high speed from the centre of our Galaxy to its outskirts. This could provide key information about some of the most obscure regions of the Milky Way.

http://sci.esa.int/gaia/59263-artificial-brain-helps-gaia-catch-speeding-stars/

« Last Edit: 07/08/2017 09:04 PM by Star One »

Offline bolun

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Re: ESA - Gaia updates
« Reply #106 on: 08/21/2017 11:03 AM »
Preview of Gaia’s sky in colour

This map is a preview of Gaia’s measurements of the sky in colour.

The image includes preliminary data from 18.6 million bright stars observed by Gaia between July 2014 and May 2016, and it shows the middle value of the colours of all stars that are observed in each pixel. The colour of each star is estimated by comparing the total amount of blue and red light recorded by Gaia.

The Galactic Plane, corresponding to the most densely populated region of our Milky Way galaxy, stands out as the roughly horizontal feature across the image. The reddest regions in the map, mainly found near the Galactic Centre, correspond to dark areas in the density of stars: these are clouds of dust that obscure part of the starlight, especially at blue wavelengths, making it appear redder. It is also possible to see the two Magellanic Clouds – small satellite galaxies of our Milky Way – in the lower part of the map.

Gaia’s first full-colour all-sky map, based on data for more than 1 billion stars, will be unleashed in its highest resolution in April 2018.

Full story: Sneak peek of Gaia's sky in colour

http://www.esa.int/spaceinimages/Images/2017/08/Preview_of_Gaia_s_sky_in_colour

Image credit: ESA/Gaia/DPAC/CU5/CU8/DPCI/F. De Angeli, D.W. Evans, M. Riello, M. Fouesneau, R. Andrae, C.A.L. Bailer-Jones

Offline jebbo

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Offline bolun

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Re: ESA - Gaia updates
« Reply #108 on: 12/27/2017 10:35 AM »

Offline Star One

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Offline jebbo

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Re: ESA - Gaia updates
« Reply #110 on: 01/25/2018 11:34 AM »
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@ESAGaia and #DPAC are happy to announce the release date and expected contents of #GaiaDR2: https://www.cosmos.esa.int/web/gaia/dr2

https://twitter.com/ESAGaia/status/956504296715145216

DR2 will be 25th April 2018! 

--- Tony

Offline Star One

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Re: ESA - Gaia updates
« Reply #111 on: 02/28/2018 03:53 PM »
Chasing a stellar flash


Offline bolun

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Re: ESA - Gaia updates
« Reply #112 on: 03/21/2018 08:56 PM »
Gaia status update: safe mode and recovery

21 March 2018

Last month, ESA's Gaia satellite experienced a technical anomaly followed by a 'safe mode' event. After thorough examination, the spacecraft was successfully recovered and resumed normal scientific operations, while the mission team keeps investigating the exact cause of the anomaly.

http://sci.esa.int/gaia/60098-gaia-status-update-safe-mode-and-recovery/

Offline bolun

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Re: ESA - Gaia updates
« Reply #113 on: 04/04/2018 03:32 PM »
GAIA'S VIEW OF DARK INTERSTELLAR CLOUDS

03 April 2018

While charting the positions of more than a billion stars, ESA's Gaia mission provides all-important information even about the dark patches of the sky where fewer stars are observed. These images, based on Gaia's first data release, are an appetizer to the astronomical riches that will be unleashed with the mission's second release on 25 April.

http://sci.esa.int/gaia/60131-gaia-s-view-of-dark-interstellar-clouds/

Offline Star One

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Re: ESA - Gaia updates
« Reply #114 on: 04/05/2018 08:23 PM »
HOW MANY STARS TO EXPECT IN GAIA'S SECOND DATA RELEASE

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05 April 2018

As astronomers worldwide are preparing to explore the second data release of ESA's Gaia satellite, the Data Processing and Analysing Consortium announced just how many sources will be included in the new catalogue, which will be made public on 25 April.[/quote{

http://sci.esa.int/gaia/60146-how-many-stars-to-expect-in-gaia-s-second-data-release/

Offline TakeOff

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Re: ESA - Gaia updates
« Reply #115 on: 04/06/2018 05:20 AM »
14,000 Solar system objects are expected in DR2. Could Gaia detect Oort cloud objects microlensing a background star? What kinds of Ss objects is it detecting, Main belt asteroids, or NEAs?

Online jgoldader

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Re: ESA - Gaia updates
« Reply #116 on: 04/06/2018 10:23 AM »
14,000 Solar system objects are expected in DR2. Could Gaia detect Oort cloud objects microlensing a background star? What kinds of Ss objects is it detecting, Main belt asteroids, or NEAs?

It should be mostly main-belt asteroids, possibly NEOs, depending on how good the algorithms are that they're using to match observations of fast moving things (connecting the dots, if you will).

But a quick check shows Gaia should go down to 20th magnitude (probably in uncluttered areas only), whereas Pluto's more than 100x brighter.  So, direct detection of some big KBOs/TNOs should be possible. But Oort Cloud... I'd say unlikely, because the reflected brightness scales like 1/r^4 (inverse square both ways) so Pluto would be visible out to about 3x, maybe a little more, than its current distance.  You'd need something a lot bigger to be seen in the Oort cloud.  Microlensing would simply look to be a transient, I'd suppose.

The observing arcs should be long enough to give half decent prelim orbits for bright TNOs, could be very interesting to see what this does to statistics for the TNO orbits from which Planet 9 has been hypothesized.
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Offline Star One

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Re: ESA - Gaia updates
« Reply #117 on: 04/06/2018 11:14 AM »
14,000 Solar system objects are expected in DR2. Could Gaia detect Oort cloud objects microlensing a background star? What kinds of Ss objects is it detecting, Main belt asteroids, or NEAs?

It should be mostly main-belt asteroids, possibly NEOs, depending on how good the algorithms are that they're using to match observations of fast moving things (connecting the dots, if you will).

But a quick check shows Gaia should go down to 20th magnitude (probably in uncluttered areas only), whereas Pluto's more than 100x brighter.  So, direct detection of some big KBOs/TNOs should be possible. But Oort Cloud... I'd say unlikely, because the reflected brightness scales like 1/r^4 (inverse square both ways) so Pluto would be visible out to about 3x, maybe a little more, than its current distance.  You'd need something a lot bigger to be seen in the Oort cloud.  Microlensing would simply look to be a transient, I'd suppose.

The observing arcs should be long enough to give half decent prelim orbits for bright TNOs, could be very interesting to see what this does to statistics for the TNO orbits from which Planet 9 has been hypothesized.

What about detecting Planet 9 itself?

Online jgoldader

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Re: ESA - Gaia updates
« Reply #118 on: 04/06/2018 01:10 PM »
What about detecting Planet 9 itself?

That's the million dollar question!  :) 

But I believe, from Brown's website, it could be 22nd mag or fainter (and 22nd magnitude is about 6 times fainter than Gaia's limit of 20th mag).  And Gaia's completeness at 20th magnitude won't be as high *in* the Galactic plane as *out* of the plane. 

My gut says Gaia probably won't see Putative Planet 9 (<50% chance), though I'd be happy to be wrong.  However, I think it's more likely Gaia will discover a good number of TNOs, and if gets a bunch of the really high semi major axis ones, those might be sufficient to make (or break) the statistical case for Planet 9.  We'll know soon!
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Offline Star One

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Re: ESA - Gaia updates
« Reply #119 on: 04/06/2018 01:40 PM »
What about detecting Planet 9 itself?

That's the million dollar question!  :) 

But I believe, from Brown's website, it could be 22nd mag or fainter (and 22nd magnitude is about 6 times fainter than Gaia's limit of 20th mag).  And Gaia's completeness at 20th magnitude won't be as high *in* the Galactic plane as *out* of the plane. 

My gut says Gaia probably won't see Putative Planet 9 (<50% chance), though I'd be happy to be wrong.  However, I think it's more likely Gaia will discover a good number of TNOs, and if gets a bunch of the really high semi major axis ones, those might be sufficient to make (or break) the statistical case for Planet 9.  We'll know soon!

So we can see a lot more of the flock but probably not the shepherd.

Tags: gaia