RAVE (survey)

Last updated

RAdial Velocity Experiment
Alternative namesRAVE
Website www.rave-survey.aip.de/rave/
[ edit on Wikidata]

RAVE (RAdial Velocity Experiment) is a multi-fiber spectroscopic astronomical survey of stars in the Milky Way using the 1.2-metre UK Schmidt Telescope of the Australian Astronomical Observatory (AAO). The RAVE collaboration consists of researchers from over 20 institutions around the world and is coordinated by the Leibniz Institute for Astrophysics Potsdam (AIP).

Contents

As a southern hemisphere survey covering 20,000 square degrees of the sky, RAVE's primary aim is to derive the radial velocity of stars from the observed spectra. Additional information is also derived such as effective temperature, surface gravity, metallicity, photometric parallax and elemental abundance data for the stars.

On April 5, 2013 RAVE concluded its phase of data taking. In an almost ten year observing campaign, a total of 574,630 spectra have been obtained on 483,330 individual stars by a small team of AAO observers, with other observers making occasional visits from RAVE participating institutions.

Description

RAVE is an observational program in the field of Near Field Cosmology which exploits our position inside the Milky Way to study its formation and evolution in greater detail than is possible for other galaxies. RAVE focuses on obtaining stellar radial velocities to study the motions of stars in the Milky Way's thin and thick disk and stellar halo. The vast majority of stars in our Galaxy have no velocity measurements, and particularly no time-consuming radial velocity measurements. RAVE utilizes fiber optics to perform multiple, simultaneous spectroscopy on up to 150 stars in a single observation. In this way it can obtain a representative sample of the nearby stars in our Galaxy which are all around, over a wide area of the sky.

For the majority of RAVE stars proper motion data is also available. Combining the proper motions with distances derived using the photometric parallax method, the transverse velocity of these stars can be calculated. With the observed radial velocities the full 6D phase space information for the stars is then obtainable.

RAVE is complementary to the SDSS project's SEGUE program as it a southern hemisphere, wide-field, intermediate-depth, intermediate spectral resolution survey with limited wavelength coverage. Conversely, SEGUE is a northern hemisphere survey with selected angular coverage, deep exposures, low-resolution but large wavelength coverage.

Most of the stars observed by RAVE are between 1,500 light-years (0.46  kpc ) and 13,000 light-years (4.0 kpc) from the Sun and so RAVE surveys halfway to the Galactic Center and halfway to the edge of the Galaxy's disk.[ citation needed ]

Observations

Since the end of the 6dF Galaxy Survey in 2004, the UK Schmidt telescope at Siding Spring has been dedicated to the RAVE survey. This followed the first year of the pilot phase of the survey (April 2003 - April 2004), where RAVE observed around the full moon period. RAVE exploits the wide field-of-view of the UK Schmidt (6 degrees on the sky) as well as the capabilities of the UK Schmidt's 6dF instrument.

The multi-object spectrograph 6dF (6 degree Field) utilizes interchangeable field plates with robot-positional optical fibers, with 150 fibers each. [1] Each fiber is attached to a `button' which is positioned by the robot (to a precision of 10 micrometres) in order to capture the light from one target star. Once the field plate is configured it matches the pattern of stars on the sky that it is observing. Three field plates are available, which means that one plate can be configured by the robot while another is being used in the telescope. From the telescope the light is sent down the optical fibers to the spectrograph unit to be dispersed through a diffraction grating and then recorded on a 1056 X 1027 CCD chip. [2]

An initial quality check of the data is performed at Macquarie University in Australia and the results are sent to the University of Padova, Italy for data reduction. The reduced data is then sent to the Leibniz Institute for Astrophysics Potsdam in Germany for final extraction of the radial velocities and the other stellar parameters.

Results

Studies from RAVE either concentrate on peculiar stars and objects or overall trends for the different components of our Galaxy, with a main focus of the structure and formation of the Milky Way. For example, RAVE is suited to searching for stellar streams, some of which are remnants of dwarf galaxies that merged with the Milky Way during galaxy formation. A search for a stellar stream from the Sagittarius Dwarf Elliptical Galaxy - which is currently merging with the Milky Way - in the vicinity of the sun yielded a null result, which helps constrain the shape of the Milky Way's dark halo. [3] Another study of the highest velocity stars was used to constrain the local Galactic escape velocity and so the mass of the dark halo. [4]

RAVE is a precursor to ESA's Gaia mission and studies with RAVE show the science potential of this upcoming survey of stars in the Milky Way.

Data access

RAVE data is available from the RAVE web server [5] or from the VizieR catalog. [6] The RAVE 4th Data Release, includes the radial velocities, stellar parameters (temperatures, gravities, metallicities), individual abundances and photometric parallaxes/distances as well as supplementary photometry and astrometry [7] for roughly 500 000 stars.

See also

Related Research Articles

<span class="mw-page-title-main">Andromeda Galaxy</span> Barred spiral galaxy in the Local Group

The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about 46.56 kiloparsecs approximately 2.5 million light-years from Earth and the nearest large galaxy to the Milky Way. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.

<span class="mw-page-title-main">Galactic Center</span> Rotational center of the Milky Way galaxy

The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact radio source which is almost exactly at the galactic rotational center. The Galactic Center is approximately 8 kiloparsecs (26,000 ly) away from Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius, where the Milky Way appears brightest, visually close to the Butterfly Cluster (M6) or the star Shaula, south to the Pipe Nebula.

BPS CS31082-0001, named Cayrel's Star, is an old Population II star located in a distance of 2.1 kpc in the galactic halo. It belongs to the class of ultra-metal-poor stars, specifically the very rare subclass of neutron-capture enhanced stars. It was discovered by Tim C. Beers and collaborators with the Curtis Schmidt telescope at the Cerro Tololo Inter-American Observatory in Chile and analyzed by Roger Cayrel and collaborators. They used the Very Large Telescope (VLT) at the European Southern Observatory in Paranal, Chile for high-resolution optical spectroscopy to determine elemental abundances. The thorium-232 to uranium-238 ratio was used to determine the age. It is estimated to be about 12.5 billion years old, making it one of the oldest known.

The Sloan Digital Sky Survey or SDSS is a major multi-spectral imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project began in 2000 and was named after the Alfred P. Sloan Foundation, which contributed significant funding.

<span class="mw-page-title-main">S Doradus</span> Star in the Large Magellanic Cloud

S Doradus is one of the brightest stars in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way, located roughly 160,000 light-years away. The star is a luminous blue variable, and one of the most luminous stars known, having a luminosity varying widely above and below 1,000,000 times the luminosity of the Sun, although it is too far away to be seen with the naked eye.

<span class="mw-page-title-main">Monoceros Ring</span> Complex, ringlike filament of stars that wraps around the Milky Way three times

The Monoceros Ring(monoceros: Greek for 'unicorn') is a long, complex, ring of stars that wraps around the Milky Way three times. This is proposed to consist of a stellar stream torn from the Canis Major Dwarf Galaxy by tidal forces as part of the process of merging with the Milky Way over a period of billions of years, although this view has long been disputed. The ring contains 100 million solar masses and is 200,000 light years long.

<span class="mw-page-title-main">Milky Way</span> Galaxy containing our Solar System

The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλακτικός κύκλος, meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Doust Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

<span class="mw-page-title-main">NGC 3201</span> Low galactic latitude globular cluster in the constellation Vela

NGC 3201 is a low galactic latitude globular cluster in the southern constellation of Vela. It has a very low central concentration of stars. This cluster was discovered by James Dunlop on May 28, 1826 and listed in his 1827 catalogue. He described it as "a pretty large pretty bright round nebula, 4′ or 5′ diameter, very gradually condensed towards the centre, easily resolved into stars; the figure is rather irregular, and the stars are considerably scattered on the south".

In astronomy, the Arcturus moving group or Arcturus stream is a moving group or stellar stream, discovered by Olin J. Eggen (1971), comprising 53 stars moving at 275,000 miles per hour, which includes the nearby bright star Arcturus. It comprises many stars which share similar proper motion and so appear to be physically associated.

In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space.

Lambda Mensae, Latinized from λ Mensae, is an orange-hued star in the southern constellation of Mensa. It has an apparent visual magnitude of 6.53, which places it at or near the limit on stars visible to the naked eye. According to the Bortle scale, it requires a dark night from rural skies for this star to be viewed. Though it has the designation Lambda, it is actually the twenty-fourth-brightest star in the constellation and not the eleventh-brightest.

Rosemary F. G. Wyse is a Scottish astrophysicist and professor in the physics and astronomy department at Johns Hopkins University.

<span class="mw-page-title-main">Thick disk</span> Structural component of some galaxies

The thick disk is one of the structural components of about 2/3 of all disk galaxies, including the Milky Way. It was discovered first in external edge-on galaxies. Soon after, it was proposed as a unique galactic structure in the Milky Way, different from the thin disk and the halo in the 1983 article by Gilmore & Reid. It is supposed to dominate the stellar number density between 1 and 5 kiloparsecs above the galactic plane and, in the solar neighborhood, is composed almost exclusively of older stars. Its stellar chemistry and stellar kinematics are also said to set it apart from the thin disk. Compared to the thin disk, thick disk stars typically have significantly lower levels of metals—that is, the abundance of elements other than hydrogen and helium.

<span class="mw-page-title-main">HD 33579</span> Star in the constellation Dorado

HD 33579 is a white/yellow hypergiant and one of the brightest stars in the Large Magellanic Cloud (LMC). It is a suspected variable star.

HD 91496 is a giant star in the constellation Carina, with an apparent magnitude is 4.92 and an MK spectral class of K4/5 III. It has been suspected of varying in brightness, but this has not been confirmed.

Tau6 Eridani, Latinized from τ6 Eridani, is a single star in the equatorial constellation of Eridanus, located near the constellation border with Fornax. It has a yellow-white hue with an apparent visual magnitude of 4.22, which is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to this star is around 57.5 light years. It is drifting further away with a radial velocity of +8 km/s.

<span class="mw-page-title-main">Gerard F. Gilmore</span>

Gerard Francis Gilmore FRS FRAS FInstP is Professor of Experimental Philosophy, in the Institute of Astronomy, at the University of Cambridge. His research has centred on studying stars in the Galaxy to understand its structure and evolutionary history.

<span class="mw-page-title-main">HV 11423</span> Star in the Small Magellanic Cloud in the constellation Tucana

HV 11423 is a red supergiant star in the Small Magellanic Cloud. It is about 200,000 light-years away towards the constellation of Tucana.

<span class="mw-page-title-main">EBLM J0555-57</span> Triple star system in the constellation Pictor

EBLM J0555-57 is a triple star system approximately 670 light-years from Earth. EBLM J0555-57Ab, the smallest star in the system, orbits its primary star with a period of 7.8 days, and at the time of discovery, was the smallest known star with a mass sufficient to enable the fusion of hydrogen in its core.

WOH G17 is a possible red supergiant (RSG) located in the Large Magellanic Cloud (LMC) or a Mira variable asymptotic giant branch (AGB) star in the constellation of Mensa. The star is often considered to be a foreground object; much closer than the LMC, probably in the Milky Way, and therefore is potentially much smaller and less luminous.

References

  1. ↑ Jones, D. Heath; Saunders, Will; Colless, Matthew; Read, Mike A.; Parker, Quentin A.; Watson, Fred G.; Campbell, Lachlan A.; Burkey, Daniel; Mauch, Thomas; et al. (2004). "The 6dF Galaxy Survey: Samples, observational techniques and the first data release". Monthly Notices of the Royal Astronomical Society . 355 (3): 747–763. arXiv: astro-ph/0403501 . Bibcode:2004MNRAS.355..747J. doi:10.1111/j.1365-2966.2004.08353.x. S2CID   119351906.
  2. ↑ Steinmetz, M.; Zwitter, T.; Siebert, A.; Watson, F. G.; Freeman, K. C.; Munari, U.; Campbell, R.; Williams, M.; Seabroke, G. M.; et al. (2006). "The Radial Velocity Experiment (RAVE): First Data Release". The Astronomical Journal. 132 (4): 1645–1668. arXiv: astro-ph/0606211 . Bibcode:2006AJ....132.1645S. doi:10.1086/506564.
  3. ↑ Seabroke, G. M.; Gilmore, G.; Siebert, A.; Bienaymé, O.; Binney, J.; Bland-Hawthorn, J.; Campbell, R.; Freeman, K. C.; Gibson, B.; Grebel, E. K.; Helmi, A.; Munari, U.; Navarro, J. F.; Parker, Q. A.; Siviero, A.; Steinmetz, M.; Watson, F. G.; Wyse, R. F. G.; Zwitter, T.; Peñarrubia, J.; Smith, M. C.; Williams, M. (2008). "Is the sky falling? Searching for stellar streams in the local Milky Way disc in the CORAVEL and RAVE surveys". Monthly Notices of the Royal Astronomical Society. 384 (1): 11–32. arXiv: 0709.4219 . Bibcode:2008MNRAS.384...11S. doi:10.1111/j.1365-2966.2007.12513.x. S2CID   119102965.
  4. ↑ Smith, Martin C.; Ruchti, Gregory R.; Helmi, Amina; Wyse, Rosemary F. G.; Fulbright, J. P.; Freeman, K. C.; Navarro, J. F.; Seabroke, G. M.; Steinmetz, M.; et al. (2007). "The RAVE survey: Constraining the local Galactic escape speed". Monthly Notices of the Royal Astronomical Society. 379 (2): 755–772. arXiv: astro-ph/0611671 . Bibcode:2007MNRAS.379..755S. doi:10.1111/j.1365-2966.2007.11964.x. S2CID   14055245.
  5. ↑ "RAVE data access" . Retrieved 18 September 2010.
  6. ↑ "RAVE data on VizieR" . Retrieved 18 September 2010.
  7. ↑ Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Boeche, C.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; De Laverny, P.; Recio-Blanco, A.; Williams, M. E. K.; Piffl, T.; Enke, H.; Roeser, S.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Carrillo, I.; Anguiano, B.; Burton, D.; Campbell, R.; Cass, C. J. P.; Fiegert, K.; Hartley, M.; Parker, Q. A.; Reid, W.; Ritter, A.; Russell, K. S.; et al. (2013). "The Radial Velocity Experiment (RAVE): Fourth Data Release". The Astronomical Journal. 146 (5): 134. arXiv: 1309.4284 . Bibcode:2013AJ....146..134K. doi:10.1088/0004-6256/146/5/134. S2CID   2532948.

Further reading

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.