Tuesday, 30 September 2014

A new catalogue of over 200 million stars in the Milky Way galaxy

Recently one of the surveys that I'm a member of made a huge data release including over 200 million stars from our own galaxy, the Milky Way. We've made the data available to the entire world, not just the astronomical community, but everyone in the world! Astronomers love to share data!

The Isaac Newton Telescope on La Palma (Credit: ING)

The survey in question is the INT Photometric H-Alpha Survey (IPHAS), which has, over the last 11 years been using the Isaac Newton Telescope on the island of La Palma to survey our own galaxy to an unprecedented level of detail.

IPHAS is a photometric survey, meaning the goal of the survey is to measure photometry for all the sources it observes (astronomers refer to most objects as 'sources' until they're sure exactly what they are: stars, planets or galaxies). Photometry is the easiest measurement astronomers can make, since all you have to do is measure how bright an object is using a certain filter. IPHAS uses two 'broad' filters and one 'narrow' Hα filter (more on the awesomeness of this filter and what you can do with it in a future post).

The Milky Way (Credit: Wikimedia Commons)
Our own galaxy is visible to us as a glowing band of light stretching across the sky, known as the Milky Way. It appears this way to us because we (the Earth, the Sun and the entire solar system) are within the galaxy, and so we see the galaxy all around us, but concentrated in a band of light that makes up the disk of our galaxy. Astronomers refer to this as the Galactic Plane.

Surveying our galaxy is not easy because the stars can often be very crowded together (hence why they often appear blurred as a bright band of light instead of individual stars), so to do the job properly requires a high-resolution telescope and instrument, but also one that could invest a lot of time and effort into a single project such as this.

In 2003 the Isaac Newton Telescope was just such a telescope and so the IPHAS collaboration was born, led by Janet Drew (currently at the University of Hertfordshire where I am also based). I joined the collaboration in 2004 when I started my PhD at University College London and have been involved in the survey ever since, participating in the telescope observations, analysing data, and writing papers. Its been great to be involved in such a large and exciting project such as this.

After 11 years of taking data, sorting and organising the data, and doing some exciting science as well, the catalog is finally finished. It contains information on 219 million detected objects, the vast majority of which are stars in our own galaxy. It's an example of what astronomers (and data scientists) refer to as 'big data': huge catalogs of data, observations and measurements that can be sorted, filtered and analysed en masse.

One example of this is the image shown below, which was put together by IPHAS astronomer Hywel Farnhill. This map shows part of the Galactic Plane that IPHAS has been surveying, mostly covering the constellation of Cygnus, but stretching to Sagitta on the right.

IPHAS stellar density map (Credit: Hywel Farnhill)

This map is a stellar density map, showing the density of stars across the Galactic Plane, i.e. the number of stars detected by the IPHAS survey in each area of the plane, and its really detailed! Click here to see a high-resolution version of the image, zoom into it, and have a look at the exquisite level of detail that can be seen. The brightest parts are where we detect the most stars and the darkest parts are where we detect the least stars.

Most of this structure is actually due to the obscuring effects of interstellar dust, and not actually the distribution of stars in our galaxy (though this does contribute). Interstellar dust, which is mostly very small silicate rocks (similar to those found on Earth), absorbs starlight, particularly at visible wavelengths, and leads to the fine structure that you can see in this image. Tracing the distribution of this dust is really important to astronomers because of the huge influence it can have when it absorbs the light from the stars and galaxies we are trying to study.

You can read more about the survey on the IPHAS website, learn about the data release itself in this published paper by IPHAS astronomer and catalog maestro Geert Barentsen, or read the press release from the Royal Astronomical Society. If you'd like to access the data (and please do) you can get the entire set of data, for free, from the Vizier web archive.


  1. 3d bioprinting = Immortality = go to stars

  2. ...interstellar travel constant acceleration (Sun-Deneb: 1000g)... Earth...the 2 ships that will go formation flying for mutual assisting if there are problems...indestructible structures made of Hexapentas material, awaiting in airport the arrival of passengers... Day 1: zero-speed... THE SHIPS TAKEOFF►... navigation computer places on screen the spacecraft in the center of sphere...spherical\tridimensional\spatial Heading: Deneb... Antimatter rocket engines...ON... Here we go...goooooo!...1g...10g...100g...constant acceleration cruise: 1000g (9.8 kms/sec²)... Inside the living areas (the same as going submerged in water: constant acceleration downwards...less...constant thrust, constant acceleration, from water upwards)...the gravitational transformers, perfectly synchronized with the acceleration, running: 1000g constant acceleration toward the floor ↓↓(motors)↓↓...less...999g constant acceleration toward the ceiling ↑↑(gravitational transformers)↑ = 1g constant acceleration toward the floor↓... 8.5 hours: light-speed = 1c...the fusion reactor as an artificial sun illuminating the immense Vital Support Gardens to lowering, from their comfortable apartments, cheerful passage to the pool...the electromagnetic shield anti-radiation...antigravity fields generator run forward, working: light objects away from the path of the ship...and trajectory ship away from the heavy objects...superluminal-speed > 1c... 42.5 hours: reaches hyperluminal-speed = 5c... Day 508: Half Journey...1000 light years...high hyperluminal-speed = 1435.39c... OFF engines...a few minutes of weightlessness during maneuver...the ship rotates 180º around its axis...motors ON again and ...◄STARTS TO BRAKE... Day 1017 (2.79 years): End Path party...2000 light years...zero-speed... The forever young passage of the 1st Immortal Generation (3D Bioprinting...Telomerase...modified Biological Timers...) disembarks at destination: an extra-stellar planet which came errant to orbit of Deneb giant.

  3. ...interstellar travel (thousands G of constant acceleration)... gravitation, dimensions and inertia: the Matter... The electromagnetic radiation: quanta (pieces) of energy in discrete amounts (minimum and independents), photons, which move in waves... Why energy quanta (photons) are attracted by gravitational fields of "stellar lenses" curving their trajectories and move on...go ahead because they have inertia...and are attracted because the Energy also has Gravitation, but does not manifest because it no emits Gravitons, or emits in imperceptible degree, because it has to be condensed enough like in matter for that, but it is sensitive to Gravitation from Matter emits... Energy and Gravitation "associated"...and...the Gravitational Force is another manifestation, unknown yet, from Energy...(no "curvature" of that called "space-time" relativistic)... When was finished contraction, F=G(m1*m2)/d², the pre-early Universe; (no relativistic "singularity", but it was a gyratory Sphere with dimensions and outside the Infinite Empty Space); was need have as its starting point towards the expansion, one first action: when all the Universe Matter was almost infinitely compressed and hot with all subatomic particles in direct contact without empty space among them, then →Gravity← becomes ←Antigravity→, those hyper-dense Matter becomes Energy ("infinites": Temperature + Energy + suddenly Antigravity = Big-Bang)...already again how a New Universe in expansion cooling, appears again the Matter from Energy...and again antigravity becomes normal Gravity... Its particle exchange, the theoretical Graviton yet...maybe "quanta of gravitational energy... The Energy (e=mc²) is sensitive to Gravitation but hardly emits Gravitons... The Matter, which is condensed Energy (e=m/c²), emits now Gravitons proportionally to its density... The Matter with normal density, naturally, emits few Gravitons (weak intensity of gravitational force). But...if someday could transform some of matter, not in Energy by annihilation with antimatter but entirely in Gravitational Force with an exponential Gravitons (or antigravitons) emission...would have a way to amplify the Gravitational Force a certain amount of mass... Light (photons) can be directed with a mirror... Gravity (gravitophotons) perhaps also can be directed someday the same such as light in a car´s headlight placed in ceiling looking downwards... This would be necessary for having artificial gravitational attraction only toward the ceiling in all the floors of the ship, each down´s floor must have less own gravity-power because receives gravitational attraction from all up´s floors. This can be difficult to observe in Universe because, although with unequal intensity, there are Gravitational Forces actuating from all directions. But in...gravitational transformers...for spacecrafts to thousands G of constant acceleration...

  4. (2)...interstellar travel (thousands G of constant acceleration)... The Electromagnetic and Gravitational Forces have some obvious similarities (fulfill the Law of Inverse of the Square) as both are "inversely proportional to the square of the distance that separate"...distance between the poles of two magnets the Electromagnetic...and distances between the centers of two masses the Gravitational... Just as now can using the Electromagnetic Force for obtain different voltages, currents and electrical powers...electrical transformers...perhaps someday when that mysterious Gravitational Force reveal its secrets, can using it and amplify its emission (converting the mass exponentially in Gravitons) somehow for obtain different intensities and gravitational powers...gravitational transformers... Spacecrafts with indestructible structures and the distribution of a building of housing flats (where are the foundations would the nozzles)... Antigravitational fields directed forward would go shoving and accelerating the space´s dust until reaching (the dust) almost ship-speed the dust´s clous matter-feeder ("fuel") always placed at ship´s front (cloud 1st half travel accelerating)...and placed ship´s astern when ship rotates 180º (new cloud 2nd half travel decelerating), leading dust with Gravitational peripheral fields; already the dust with slow differential-speed between dust and ship (each dust´s particle already does not is a bullet)...((at Halfway and also before Finish travel, the ship overtakes and consumes totally the dust´s cloud: halfway, max speed ship and max speed cloud, when ship ◄STARTS TO BRAKE, the 1st cloud would continue with its max speed free forward already alone without the ship... For there are not dangerous speedy free lethal dust´s particles at Space...)); towards the ship converters matter/antimatter, where at half of matter would transform in antimatter to feed the insatiable demand for the voracious annihilation rocket engines ejecting the appreciable mass of the Pions, produced in large quantities, through the nozzles to the speed of light...a rocket´s thrust = ejection by nozzle (mass*speed) in each second...and maintaining indefinitely to the ship at thousands G of constant acceleration. Powerful gravitational fields inside the living areas would counteract the HUGE CONSTANT ACCEELERATION of the ship, keeping them to 1 G...

  5. ...3D Bioprinting-Immortality (biological timers)... Forever young with modified Biological Timers...which are the biological timers?, where are them? (genes, hypothalamus...), how functioning them?, how can modify them (telomerase...) for maintenance the hormones production, enzymes, cellular regeneration...all Eternity at same level of the 18 years old?... Have to accelerate Research about Memory and the Space´s Colonization... Immortality comes...

  6. ...interstellar travel constant acceleration (times to reach light-speed)... 1g (9.8 mts/sec²)=354 days ...↓... 0.5g (4.9 mts/sec²)=1.94 years ...↓... 0.25g (2.45 mts/sec²)=3.88 years ...↓... 0.1g (98 cms/sec²)=9.7 years ...↓... 0.01g (9.8 cms/sec²)=97 years ...↓... 0.001g (9.8 mms/sec²)=970 years ______ Huge constant acceleration the ship, living areas to 1g: inside the living areas..."the same as going submerged in water"...↓↓↓↓g (motors)...less... ↑↑↑g (gravitational transformers)=↓g... ...↨... 2g (19.6 mts/sec²)=177 days ...↨... 10g (98 mts/sec²)=35.4 days ...↨... 100g (980 mts/sec²)=3.54 days ...↨... 1000g (9.8 kms/sec²)=8.5 hours ...↨... 10000g (98 kms/sec²)=51 minutes ...↨... 50000g (490 kms/sec²)=10.2 minutes ...↨... 100000g (980 kms/sec²)=5.1 minutes ...↨... 1 million G (9800 kms/sec²)=30.6 seconds... ((typewrite: interstellar travel constant acceleration))