Starship Asterisk*

Data from ESPRESSO First Light - Credit: ESO/ESPRESSO Team

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The Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) has successfully made its first observations. Installed on ESO’s Very Large Telescope (VLT) in Chile, ESPRESSO will search for exoplanets with unprecedented precision by looking at the minuscule changes in the light of their host stars. For the first time ever, an instrument will be able to sum up the light from all four VLT telescopes and achieve the light collecting power of a 16-metre telescope.

ESPRESSO has achieved first light on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile [1]. This new, third-generation echelle spectrograph is the successor to ESO’s hugely successful HARPS instrument at the La Silla Observatory. HARPS can attain a precision of around one metre per second in velocity measurements, whereas ESPRESSO aims to achieve a precision of just a few centimetres per second, due to advances in technology and its placement on a much bigger telescope. ...

ESPRESSO can detect tiny changes in the spectra of stars as a planet orbits. This radial velocity method works because a planet’s gravitational pull influences its host star, causing it to “wobble” slightly. The less massive the planet, the smaller the wobble, and so for rocky and possibly life-bearing exoplanets to be detected, an instrument with very high precision is required. With this method, ESPRESSO will be able to detect some of the lightest planets ever found [2].

The test observations included observations of stars and known planetary systems. Comparisons with existing HARPS data showed that ESPRESSO can obtain similar quality data with dramatically less exposure time. ...

bystander wrote:First Light for ESPRESSO — the Next Generation Planet Hunter
ESO Organisation Release | ESPRESSO | 2017 Dec 06

ESPRESSO has achieved first light on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile [1]. This new, third-generation echelle spectrograph is the successor to ESO’s hugely successful HARPS instrument at the La Silla Observatory. HARPS can attain a precision of around one metre per second in velocity measurements, whereas ESPRESSO aims to achieve a precision of just a few centimetres per second, due to advances in technology and its placement on a much bigger telescope. ...

• For reference: The Earth orbits at 2,978,000 cm/s so the
  (333,000 Earth mass) Sun must travel ~9 cm/s in the opposite direction

neufer wrote:

• For reference: The Earth orbits at 2,978,000 cm/s so the
  (333,000 Earth mass) Sun must travel ~9 cm/s in the opposite direction

MargaritaMc wrote:

neufer wrote:

• For reference: The Earth orbits at 2,978,000 cm/s so the
  (333,000 Earth mass) Sun must travel ~9 cm/s in the opposite direction

Thanks Art, that is most helpful.

BDanielMayfield wrote:
Ditto. saved me from doing the math myself.

MargaritaMc wrote:
I'm embarrassed to admit that I can't remember how to do this particular calculation (I think that I once knew, but the elderly brain is getting slow and rusty), so I'd be very grateful if someone would give the equation needed. And possibly explain the physics?

neufer wrote:

MargaritaMc wrote:
I'm embarrassed to admit that I can't remember how to do this particular calculation (I think that I once knew, but the elderly brain is getting slow and rusty), so I'd be very grateful if someone would give the equation needed. And possibly explain the physics?

Momentum of the Earth = M_E x V_E = M_E x ~3,000,000 cm/s = 3,000,000 M_E cm/s
Momentum of the Sun = M_S x V_S = 333,000 M_E x ~(-9 cm/s) = -3,000,000 M_E cm/s

“ Law III: To every action there is always opposed an equal reaction:
or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.

ESPRESSO instrument achieves first light with all four Unit Telescopes

Credit: ESO/L. Calçada

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The ESPRESSO instrument on ESO’s Very Large Telescope in Chile has used the combined light of all four of the 8.2-metre Unit Telescopes for the first time. Combining light from the Unit Telescopes in this way makes the VLT the largest optical telescope in existence in terms of collecting area.

One of the original design goals of ESO’s Very Large Telescope (VLT) was for its four Unit Telescopes (UTs) to work together to create a single giant telescope. With the first light of the ESPRESSO spectrograph using the four-Unit-Telescope mode of the VLT, this milestone has now been reached [1]. ...

A system of mirrors, prisms and lenses transmits the light from each VLT Unit Telescope to the ESPRESSO spectrograph up to 69 metres away. Thanks to these complex optics, ESPRESSO can either collect the light from up to all four Unit Telescopes together, increasing its light-gathering power, or alternatively receive light from any one of the Unit Telescopes independently, allowing for more flexible usage of observing time. ESPRESSO was specially developed to exploit this infrastructure.

Light from the four Unit Telescopes is routinely brought together in the VLT Interferometer (VLTI) for the study of extremely fine detail in comparatively bright objects. But interferometry, which combines the beams “coherently”, cannot exploit the huge light-gathering potential of the combined telescopes to study faint objects [3]. ...