ESPRESSO
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ESPRESSO (Echelle SPectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations)[1] is a third-generation, fiber fed, cross-dispersed, echelle spectrograph mounted on the European Southern Observatory's Very Large Telescope (VLT). The unit saw its first light on September 25, 2016.[2][3]
ESPRESSO is the successor of a line of echelle spectrometers that include CORAVEL, Elodie, Coralie, and HARPS. It measures changes in the light spectrum with great sensitivity, and will be used to search for Earth-size rocky exoplanets via the radial velocity method. For example, Earth induces a radial-velocity variation of 9 cm/s on the Sun; this gravitational "wobble" causes minute variations in the color of sunlight, invisible to the human eye but detectable by the instrument.[4] The telescope light is fed to the instrument, located in the VLT Combined-Coude Laboratory 70 meters away from the telescope, where the light from up to 4 Unit Telescopes of the VLT can be combined. The Principal Investigator is Francesco Pepe.
Contents
Sensitivity[edit]
ESPRESSO will build on the foundations laid by the High Accuracy Radial Velocity Planet Searcher (HARPS) instrument at the 3.6-metre telescope at ESO’s La Silla Observatory. ESPRESSO will benefit not only from the much larger combined light-collecting capacity of the four 8.2-metre VLT Unit Telescopes, but also from improvements in the stability and calibration accuracy that are now possible by laser frequency comb technology. The requirement is to reach 10 cm/s,[6] but the aimed goal is to obtain a precision level of a few cm/s. This would mean a large step forward over current radial-velocity spectrographs like ESO's HARPS. The HARPS instrument can attain a precision of 97 cm/s (3.5 km/h),[7] with an effective precision of the order of 30 cm/s,[8] making it one of only two spectrographs worldwide with such accuracy.[citation needed] The ESPRESSO would greatly exceed this capability making detection of Earth-size planets from ground-based instruments possible. Commissioning of ESPRESSO at the VLT started late 2017.
The instrument is capable of operating in 1-UT mode (using one of the telescopes) and in 4-UT mode. In 4-UT mode, in which all the four 8-m telescopes are connected incoherently to form a 16-m equivalent telescope, the spectrograph will detect extremely faint objects.[4][9]
For example, for G2V type stars:
- Rocky planets around stars as faint as V ~ 9 in (in 1-UT mode)
- Neptune mass planets around stars as faint as V ~ 12 (in 4-UT mode )
- Earth-size rocky planets around stars as faint as V ~ 9 (CODEX on the E-ELT) (2025)[10]
ESPRESSO will focus the observations on the best-suited candidates: non-active, non-rotating, quiet G dwarfs to red dwarfs. It will operate at the peak of its efficiency for a spectral type up to M4-type stars.
Instrument[edit]
ESPRESSO will use as calibration a laser frequency comb (LFC), with backup of two ThAr lamps. It will have three instrumental modes: singleHR, singleUHR and multiMR. In the singleHR mode ESPRESSO can be fed by any of the four UTs.[12]
Status[edit]
All design work was completed and finalised by April 2013, with the manufacturing phase of the project commencing thereafter.[1] ESPRESSO was tested on June 3, 2016.[14] ESPRESSO first light occurred on September 25, 2016, during which they spotted various objects, among them the star 60 Sgr A.[2][3] After being shipped to Chile, installed at the VLT, ESPRESSO saw its first light there on 27 November 2017, in 1-UT mode, observing the star Tau Ceti;[15][16][17] the first star observed in the 4-UT mode was on February 3, 2018.[18][19][20]
ESPRESSO in the 1-UT mode (one single telescope used) has been opened to the astronomical community and producing scientific data since October 24, 2018. On quiet stars it has already demonstrated radial-velocity precision of 25 cm/s over a full night. However, there have been some teething problems, for example, in light collecting efficiency which was around 30% lower than expected and required. And so, some fine tuning, including replacing the parts causing the efficiency problem and subsequent re-testing, will be made on the instrument before the full 4-UT mode is open to the scientific community in April 2019.[21]
Scientific objectives[edit]
The main scientific objectives for ESPRESSO are:[22][23]
- The measurement of high precision radial velocities of solar type stars for the search for rocky planets in the habitable zone of their star.
- The measurement of the variation of the physical constants
- The analysis of the chemical composition of stars in nearby galaxies.
Consortium[edit]
ESPRESSO is being developed by a consortium consisting on the European Southern Observatory (ESO) and seven scientific institutes:
- Centre for Astrophysics of the University of Porto (Portugal)
- Faculdade de Ciências da Universidade de Lisboa, CAAUL & LOLS (Portugal)
- Trieste Astronomical Observatory (Italy)
- Brera Astronomical Observatory (Italy)
- Instituto de Astrofísica de Canarias (Spain)
- Physics Institute of the University of Bern (Switzerland)
- University of Geneva (Switzerland)
- Institute of Astrophysics and Space Sciences (Portugal)
ESPRESSO specifications[edit]
| ESPRESSO | |||
|---|---|---|---|
| Telescope | VLT (8m) | ||
| Scope | Rocky planets | ||
| Sky aperture | 4 arcsec | ||
| R | ~200.000 | ||
| λ coverage | 380 nm-686 nm[24] | ||
| λ precision | 5 m/s | ||
| RV stability | < 10 cm/s | ||
| 4-VLT mode (D = 16 m) with RV = 1 m/s | |||
| Source:[10][25][23] | |||
Radial velocity comparison tables[edit]
| Planet Mass | Distance AU |
Radial velocity (vradial) |
Note |
|---|---|---|---|
| Jupiter | 1 | 28.4 m/s | |
| Jupiter | 5 | 12.7 m/s | |
| Neptune | 0.1 | 4.8 m/s | |
| Neptune | 1 | 1.5 m/s | |
| Super-Earth (5 M⊕) | 0.1 | 1.4 m/s | |
| Alpha Centauri Bb (1.13 ± 0.09 M⊕) | 0.04 | 0.51 m/s | (1[26]) |
| Super-Earth (5 M⊕) | 1 | 0.45 m/s | |
| Earth | 0.09 | 0.30 m/s | |
| Earth | 1 | 0.09 m/s | |
| Source: Luca Pasquini, power-point presentation, 2009[10] Notes: (1) Most precise vradial measurements ever recorded. ESO's HARPS spectrograph was used.[26][27] | |||
| Planet | Planet Type |
Semimajor Axis (AU) |
Orbital Period |
Radial velocity (m/s) |
Detectable by: |
|---|---|---|---|---|---|
| 51 Pegasi b | Hot Jupiter | 0.05 | 4.23 days | 55.9[28] | First-generation spectrograph |
| 55 Cancri d | Gas giant | 5.77 | 14.29 years | 45.2[29] | First-generation spectrograph |
| Jupiter | Gas giant | 5.20 | 11.86 years | 12.4[30] | First-generation spectrograph |
| Gliese 581c | Super-Earth | 0.07 | 12.92 days | 3.18[31] | Second-generation spectrograph |
| Saturn | Gas giant | 9.58 | 29.46 years | 2.75 | Second-generation spectrograph |
| Proxima Centauri b | Habitable planet (potentially) | 0.05 | 11.19 days | 1.38[32] | Second-generation spectrograph |
| Alpha Centauri Bb | Terrestrial planet | 0.04 | 3.23 days | 0.510[33] | Second-generation spectrograph |
| Neptune | Ice giant | 30.10 | 164.79 years | 0.281 | Third-generation spectrograph |
| Earth | Habitable planet | 1.00 | 365.26 days | 0.089 | Third-generation spectrograph (likely) |
| Pluto | Dwarf planet | 39.26 | 246.04 years | 0.00003 | Not detectable |
MK-type stars with planets in the habitable zone[edit]
| Stellar mass (M☉) |
Planetary mass (M⊕) |
Lum. (L0) |
Type | RHAB (AU) |
RV (cm/s) |
Period (days) |
|---|---|---|---|---|---|---|
| 0.10 | 1.0 | 8×10−4 | M8 | 0.028 | 168 | 6 |
| 0.21 | 1.0 | 7.9×10−3 | M5 | 0.089 | 65 | 21 |
| 0.47 | 1.0 | 6.3×10−2 | M0 | 0.25 | 26 | 67 |
| 0.65 | 1.0 | 1.6×10−1 | K5 | 0.40 | 18 | 115 |
| 0.78 | 2.0 | 4.0×10−1 | K0 | 0.63 | 25 | 209 |
| Source:[34][35] | ||||||
See also[edit]
| Wikimedia Commons has media related to ESPRESSO. |
- CODEX spectrograph
- CORALIE spectrograph
- Doppler spectroscopy
- ELODIE spectrograph
- EXPRES spectograph
- HIRES spectrograph
- List of extrasolar planets
- SOPHIE échelle spectrograph
References[edit]
- ^ a b "ESO - Espresso". Retrieved 2012-10-24.
- ^ a b http://www.eso.org/public/usa/announcements/ann16073/ ESPRESSO Sees Light at the End of the Tunnel
- ^ a b http://www.media.inaf.it/2016/10/17/prima-luce-espresso-coude-lab/ ESPRESSO vede la luce in fondo al “tunnel”
- ^ a b "ESPRESSO - Searching for other Worlds". Centro de Astrofísica da Universidade do Porto. 2010-10-16. Retrieved 2010-10-16.
- ^ "First Light for ESPRESSO — the Next Generation Planet Hunter". www.eso.org. Retrieved 7 December 2017.
- ^ Pepe, F.; Molaro, P.; Cristiani, S.; Rebolo, R.; Santos, N. C.; Dekker, H.; Mégevand, D.; Zerbi, F. M.; Cabral, A.; et al. (January 2014). "ESPRESSO: The next European exoplanet hunter". Astronomische Nachrichten. 335 (1): 8–20. arXiv:1401.5918. Bibcode:2014arXiv1401.5918P. doi:10.1002/asna.201312004.
- ^ "32 planets discovered outside solar system". CNN. 19 October 2009. Retrieved 4 May 2010.
- ^ "ESPRESSO – Searching for other Worlds". Centro de Astrofísica da Universidade do Porto. 16 December 2009. Retrieved 2010-10-16.
- ^ Pepe, Francesco A; Cristiani, Stefano; Rebolo Lopez, Rafael; Santos, Nuno C; et al. (July 2010). "ESPRESSO: the Echelle spectrograph for rocky exoplanets and stable spectroscopic observations" (PDF). Ground-based and Airborne Instrumentation for Astronomy III. 7735. American Institute of Physics. p. 77350F. Bibcode:2010SPIE.7735E..0FP. doi:10.1117/12.857122. Retrieved 2013-03-12.
- ^ a b c d "ESPRESSO and CODEX the next generation of RV planet hunters at ESO". Chinese Academy of Sciences. 2010-10-16. Archived from the original on July 4, 2011. Retrieved 2010-10-16.
- ^ "ESO's VLT Working as 16-metre Telescope for First Time - ESPRESSO instrument achieves first light with all four Unit Telescopes". www.eso.org. Retrieved 13 February 2018.
- ^ https://arxiv.org/abs/1401.5918 ESPRESSO: The next European exoplanet hunter
- ^ "ESO Awards Contracts for Cameras for New Planet Finder". ESO Announcement. Retrieved 8 August 2013.
- ^ https://obswww.unige.ch/wordpress/espresso/2016/06/04/espresso-first-laboratory-light/
- ^ http://www.eso.org/public/unitedkingdom/announcements/ann17053/ ESPRESSO Planet Hunter Heads for Chile
- ^ https://phys.org/news/2017-12-espressothe-planet-hunter.html
- ^ Vonarburg, Barbara (2017-12-07). "First light of ESPRESSO". NCCR PlanetS. National Centre of Competence in Research PlanetS. Retrieved 2018-11-07.
The first observation was for the star Tau Ceti. It was done using the UT1 of the VLT, the observations made on the four united telescopes will be done later.
- ^ https://www.eso.org/public/unitedkingdom/news/eso1806/ ESO’s VLT Working as 16-metre Telescope for First Time
- ^ Bratschi, Pierre (2018-02-14). "ESPRESSO: first time with the 4 UTs of the VLT". NCCR PlanetS. National Centre of Competence in Research PlanetS. Retrieved 2018-11-07.
... first light of ESPRESSO with the four VLT 8.2-meter Unit Telescopes (4UT mode) took place on Saturday February 3rd, 2018... star observed by ESPRESSO with the 4UT mode was the so-called Pepe star
- ^ Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, ESO
- ^ Barbara, Vonarburg (2018-11-28). "Fine-tuning Espresso". NCCR PlanetS. National Centre of Competence in Research PlanetS. Retrieved 2018-12-28.
ESPRESSO has been opened to the astronomical community and finally started operations on the 24th of October 2018.
- ^ ESPRESSO - A VLT Project. Accessed 12 October 2017.
- ^ a b ESPRESSO Baseline Specification. European Southern Observatory (ESO). Accessed: 12 October 2017
- ^ ESPRESSO. ESO.
- ^ Pepe, F; Molaro, P; Cristiani, S; Rebolo, R; et al. (2014). "ESPRESSO: The next European exoplanet hunter". arXiv:1401.5918v1 [astro-ph.IM].
- ^ a b "Planet Found in Nearest Star System to Earth". European Southern Observatory. 16 October 2012. Retrieved 17 October 2012.
- ^ Demory, Brice-Olivier; Ehrenreich, David; Queloz, Didier; Seager, Sara; et al. (25 March 2015). "Hubble Space Telescope search for the transit of the Earth-mass exoplanet Alpha Centauri Bb". Monthly Notices of the Royal Astronomical Society. 450 (2): 2043–2051. arXiv:1503.07528. Bibcode:2015MNRAS.450.2043D. doi:10.1093/mnras/stv673.
- ^ "51 Peg b". Exoplanets Data Explorer.
- ^ "55 Cnc d". Exoplanets Data Explorer.
- ^ Endl, Michael. "The Doppler Method, or Radial Velocity Detection of Planets". University of Texas at Austin. Retrieved 26 October 2012.[permanent dead link]
- ^ "GJ 581 c". Exoplanets Data Explorer.
- ^ "Proxima Cen b". The Extrasolar Planets Encyclopaedia.
- ^ "alpha Cen B b". Exoplanets Data Explorer.
- ^ "An NIR laser frequency comb for high precision Doppler planet surveys". Chinese Academy of Sciences. 2010-10-16. Retrieved 2010-10-16.[dead link]
- ^ Osterman, S; Diddams, S; Quinlan, F; Bally, J; Ge, J; Ycas, G (2010). "A near infrared laser frequency comb for high precision Doppler planet surveys". EPJ Web of Conferences. 16: 02002. arXiv:1003.0136. Bibcode:2011EPJWC..1602002O. doi:10.1051/epjconf/20111602002.