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1. Estimating stellar ages and metallicities from parallaxes and broadband photometry - successes and shortcomings

Author

Howes, Louise M., Lindegren, Lennart, Feltzing, Sofia, Church, Ross P., and Bensby, Thomas

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract

A deep understanding of the Milky Way galaxy, its formation and evolution requires observations of huge numbers of stars. Stellar photometry, therefore, provides an economical method to obtain intrinsic stellar parameters. With the addition of distance information - deriving reliable ages from photometry is a possibility. We have developed a Bayesian method that generates 2D probability maps of a star's age and metallicity from photometry and parallax using isochrones. Our synthetic tests show that including a near-UV passband enables us to break the degeneracy between a star's age and metallicity for certain evolutionary stages. It is possible to find well-constrained ages and metallicities for turn-off and sub-giant stars with colours including a U band and a parallax with uncertainty less than ~20%. Metallicities alone are possible for the main sequence and giant branch. We find good agreement with the literature when we apply our method to the Gaia benchmark stars, particularly for turn-off and young stars. Further tests on the old open cluster NGC 188, however, reveal significant limitations in the stellar isochrones. The ages derived for the cluster stars vary with evolutionary stage, such that turn-off ages disagree with those on the sub-giant branch, and metallicities vary significantly throughout. Furthermore, the parameters vary appreciably depending on which colour combinations are used in the derivation. We identify the causes of these mismatches and show that improvements are needed in the modelling of giant branch stars and in the creation and calibration of synthetic near-UV photometry. Our results warn against applying isochrone fitting indiscriminately. In particular, the uncertainty on the stellar models should be quantitatively taken into account. Further efforts to improve the models will result in significant advancements in our ability to study the Galaxy., Comment: Accepted for publication in A&A. 22 pages, 19 figures (+ 6 pages of appendix). Abstract abridged for the arXiv

Published
2018
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2. Using the Multi-Object Adaptive Optics demonstrator RAVEN to observe metal-poor stars in and towards the Galactic Centre

Author

Lamb, Masen, Venn, Kim, Andersen, David, Oya, Shin, Shetrone, Matthew, Fattahi, Azadeh, Howes, Louise, Asplund, Martin, Lardiere, Olivier, Akiyama, Masayuki, Ono, Yoshito, Terada, Hiroshi, Hayano, Yutaka, Suzuki, Genki, Blain, Celia, Jackson, Kathryn, Correia, Carlos, Youakim, Kris, and Bradley, Colin

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The chemical abundances for five metal-poor stars in and towards the Galactic bulge have been determined from H-band infrared spectroscopy taken with the RAVEN multi-object adaptive optics science demonstrator and the IRCS spectrograph at the Subaru 8.2-m telescope. Three of these stars are in the Galactic bulge and have metallicities between -2.1 < [Fe/H] < -1.5, and high [alpha/Fe] ~+0.3, typical of Galactic disk and bulge stars in this metallicity range; [Al/Fe] and [N/Fe] are also high, whereas [C/Fe] < +0.3. An examination of their orbits suggests that two of these stars may be confined to the Galactic bulge and one is a halo trespasser, though proper motion values used to calculate orbits are quite uncertain. An additional two stars in the globular cluster M22 show [Fe/H] values consistent to within 1 sigma, although one of these two stars has [Fe/H] = -2.01 +/- 0.09, which is on the low end for this cluster. The [alpha/Fe] and [Ni/Fe] values differ by 2 sigma, with the most metal-poor star showing significantly higher values for these elements. M22 is known to show element abundance variations, consistent with a multi-population scenario (i.e. Marino et al. 2009, 2011; Alves-Brito et al. 2012) though our results cannot discriminate this clearly given our abundance uncertainties. This is the first science demonstration of multi-object adaptive optics with high resolution infrared spectroscopy, and we also discuss the feasibility of this technique for use in the upcoming era of 30-m class telescope facilities., Comment: 23 pages, 11 figures, Accepted to MNRAS

Published
2016
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3. The EMBLA Survey -- Metal-poor stars in the Galactic bulge

Author

Howes, Louise M., Asplund, Martin, Keller, Stefan C., Casey, Andrew R., Yong, David, Lind, Karin, Frebel, Anna, Hays, Austin, Alves-Brito, Alan, Bessell, Michael S., Casagrande, Luca, Marino, Anna F., Nataf, David M., Owen, Christopher I., Da Costa, Gary S., Schmidt, Brian P., and Tisserand, Patrick

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics
Abstract

Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The EMBLA Survey successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the AAT. Here we present an abundance analysis of 10 bulge stars with -2.8<[Fe/H]<-1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data is consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that found in halo stars of the same metallicity. Two notable differences are the absence of carbon-enhanced metal-poor bulge stars, and the alpha-element abundances exhibit a large intrinsic scatter and include stars which are underabundant in these typically enhanced elements., Comment: 20 pages, 16 figures. Accepted to Monthly Notices of the Royal Astronomical Society. Online tables can be found at http://www.astro.lu.se/~louise/data

Published
2016
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4. HIP 10725: The First Solar Twin/Analogue Field Blue Straggler

Author

Schirbel, Lucas, Melendez, Jorge, Karakas, Amanda I., Ramirez, Ivan, Castro, Matthieu, Faria, Marcos A., Lugaro, Maria, Asplund, Martin, Maia, Marcelo Tucci, Yong, David, Howes, Louise, and Nascimento Jr, J. D. do

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

[Context]. Blue stragglers are easy to identify in globular clusters, but are much harder to identify in the field. Here we present the serendipitous discovery of one field blue straggler, HIP 10725, that closely matches the Sun in mass and age, but with a metallicity slightly lower than the Sun's. [Methods]. We employ high resolution (R $\sim 10^5$) high S/N (330) VLT/UVES spectra to perform a differential abundance analysis of the solar analogue HIP 10725. Radial velocities obtained by other instruments were also used to check for binarity. We also study its chromospheric activity, age and rotational velocity. [Results]. We find that HIP 10725 is severely depleted in beryllium ([Be/H] <= -1.2 dex) for its stellar parameters and age. The abundances relative to solar of the elements with Z <= 30 show a correlation with condensation temperature and the neutron capture elements produced by the s-process are greatly enhanced, while the r-process elements seem normal. We found its projected rotational velocity (v sin i = 3.3+/-0.1 km/s) to be significantly larger than solar, and incompatible with its isochrone-derived age. Radial velocity monitoring shows that the star has a binary companion. [Conclusions]. Based on the high s-process element enhancements and low beryllium abundance, we suggest that HIP 10725 has been polluted by mass-transfer from an AGB star, probably with initial mass of about 2 M_Sun. The radial velocity variations suggest the presence of an unseen binary companion, probably the remnant of a former AGB star. Isochrones predict a solar-age star, but this is in disagreement with the high projected rotational velocity and high chromospheric activity. We conclude that HIP 10725 is a field blue straggler, rejuvenated by the mass transfer process of its former AGB companion., Comment: A&A in press

Published
2015
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5. 4MOST Survey Strategy Plan

Author

Guiglion, Guillaume, Battistini, Chiara, Bell, Cameron P. M., Bensby, Thomas, Boller, Thomas, Chiappini, Cristina, Comparat, Johan, Christlieb, Norbert, Church, Ross, Cioni, Maria-Rosa L., Davies, Luke, Dwelly, Tom, De Jong, Roelof S., Feltzing, Sofia, Gueguen, Alain, Howes, Louise, Irwin, Mike, Kushniruk, Iryna, Lam, Man I, Liske, Jochen, McMahon, Richard, Merloni, Andrea, Norberg, Peder, Robotham, Aaron S. G., Schnurr, Olivier, Sorce, Jenny G., Starkenburg, Else, Storm, Jesper, Swann, Elizabeth, Tempel, Elmo, Thi, Wing-Fai, Worley, C. Clare, Walcher, C. Jakob, and The 4MOST Collaboration

Abstract

The current status of and motivation for the 4MOST survey strategy, as developed by the Consortium science team, are presented here. Key elements of the strategy are described, such as sky coverage, number of visits and total exposure times in different parts of the sky, and how to deal with different observing conditions. The task of organising the strategy is not simple, with many different surveys that have vastly different target brightnesses and densities, sample completeness levels, and signal-to-noise requirements. We introduce here a number of concepts that we will use to ensure all surveys are optimised. Astronomers who are planning to submit a Participating Survey proposal are strongly encouraged to read this article and any relevant 4MOST Survey articles in this issue of The Messenger such that they can optimally complement and benefit from the planned surveys of the 4MOST Consortium.

Published
2019
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6. The EMBLA survey – metal-poor stars in the Galactic bulge

Author

MIT Kavli Institute for Astrophysics and Space Research, Howes, Louise M., Asplund, Martin, Keller, Stefan C., Casey, Andrew R., Yong, David, Lind, Karin, Frebel, Anna L., Hays, Austin, Alves-Brito, Alan, Bessell, Michael S., Casagrande, Luca, Marino, Anna F., Nataf, David M., Owen, Christopher I., Da Costa, Gary S., Schmidt, Brian P., Tisserand, Patrick, MIT Kavli Institute for Astrophysics and Space Research, Howes, Louise M., Asplund, Martin, Keller, Stefan C., Casey, Andrew R., Yong, David, Lind, Karin, Frebel, Anna L., Hays, Austin, Alves-Brito, Alan, Bessell, Michael S., Casagrande, Luca, Marino, Anna F., Nataf, David M., Owen, Christopher I., Da Costa, Gary S., Schmidt, Brian P., and Tisserand, Patrick

Abstract

Cosmological models predict the oldest stars in the Galaxy should be found closest to the centre of the potential well, in the bulge. The Extremely Metal-poor BuLge stars with AAOmega survey (EMBLA) successfully searched for these old, metal-poor stars by making use of the distinctive SkyMapper photometric filters to discover candidate metal-poor stars in the bulge. Their metal-poor nature was then confirmed using the AAOmega spectrograph on the Anglo-Australian Telescope. Here we present an abundance analysis of 10 bulge stars with -2.8 < [Fe/H] < -1.7 from MIKE/Magellan observations, in total determining the abundances of 22 elements. Combining these results with our previous high-resolution data taken as part of the Gaia-ESO Survey, we have started to put together a picture of the chemical and kinematic nature of the most metal-poor stars in the bulge. The currently available kinematic data are consistent with the stars belonging to the bulge, although more accurate measurements are needed to constrain the stars' orbits. The chemistry of these bulge stars deviates from that found in halo stars of the same metallicity. Two notable differences are the absence of carbon-enhanced metal-poor bulge stars, and the alpha element abundances exhibit a large intrinsic scatter and include stars which are underabundant in these typically enhanced elements.

Published
2019

9. The detailed chemical composition of the terrestrial planet host Kepler-10

Author

Liu, Fan, Yong, David, Asplund, Martin, Ramirez, I, Melendez, Jorge, Gustafsson, B, Howes, Louise, Roederer, Ian U., Lambert, D.L., Bensby, T, Liu, Fan, Yong, David, Asplund, Martin, Ramirez, I, Melendez, Jorge, Gustafsson, B, Howes, Louise, Roederer, Ian U., Lambert, D.L., and Bensby, T

Abstract

Chemical abundance studies of the Sun and solar twins have demonstrated that the solar composition of refractory elements is depleted when compared to volatile elements, which could be due to the formation of terrestrial planets. In order to further examine this scenario, we conducted a line-by-line differential chemical abundance analysis of the terrestrial planet host Kepler-10 and 14 of its stellar twins. Stellar parameters and elemental abundances of Kepler-10 and its stellar twins were obtained with very high precision using a strictly differential analysis of high quality Canada–France–Hawaii Telescope, Hobby–Eberly Telescope and Magellan spectra. When compared to the majority of thick disc twins, Kepler-10 shows a depletion in the refractory elements relative to the volatile elements, which could be due to the formation of terrestrial planets in the Kepler-10 system. The average abundance pattern corresponds to ∼13 Earth masses, while the two known planets in Kepler-10 system have a combined ∼20 Earth masses. For two of the eight thick disc twins, however, no depletion patterns are found. Although our results demonstrate that several factors [e.g. planet signature, stellar age, stellar birth location and Galactic chemical evolution (GCE)] could lead to or affect abundance trends with condensation temperature, we find that the trends give further support for the planetary signature hypothesis.

Published
2016

10. The EMBLA survey – metal-poor stars in the Galactic bulge

Author

Howes, Louise M., primary, Asplund, Martin, additional, Keller, Stefan C., additional, Casey, Andrew R., additional, Yong, David, additional, Lind, Karin, additional, Frebel, Anna, additional, Hays, Austin, additional, Alves-Brito, Alan, additional, Bessell, Michael S., additional, Casagrande, Luca, additional, Marino, Anna F., additional, Nataf, David M., additional, Owen, Christopher I., additional, Da Costa, Gary S., additional, Schmidt, Brian P., additional, and Tisserand, Patrick, additional

Published
2016
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11. HIP 10725: The first solar twin/analogue field blue straggler

Author

Schirbel, L, Meléndez, J, Karakas, Amanda, Ramírez, I, Castro, Matthieu, Faria, Marcos A, Lugaro, Maria, Asplund, Martin, Tucci Maia, M, Yong, David, Howes, Louise, Do Nascimento, J. D., Schirbel, L, Meléndez, J, Karakas, Amanda, Ramírez, I, Castro, Matthieu, Faria, Marcos A, Lugaro, Maria, Asplund, Martin, Tucci Maia, M, Yong, David, Howes, Louise, and Do Nascimento, J. D.

Abstract

Context. Blue stragglers are easy to identify in globular clusters, but are much harder to identify in the field. Here we present the serendipitous discovery of one field blue straggler, HIP 10725, that closely matches the Sun in mass and age, but with a metallicity slightly lower than solar. Aims. We characterise the solar twin/analogue HIP 10725 to assess whether this star is a blue straggler. Methods. We employed spectra with high resolution (R ~ 105) and high signal-to-noise ratio (330) obtained with UVES at the VLT to perform a differential abundance analysis of the solar analogue HIP 10725. Radial velocities obtained by other instruments were also used to check for binarity. We also studied its chromospheric activity, age, and rotational velocity. Results. HIP 10725 is severely depleted in beryllium ([ Be/H ] ≤ −1.2 dex) for its stellar parameters and age. The abundances relative to solar of the elements with Z ≤ 30 show a correlation with condensation temperature, and the neutron capture elements produced by the s-process are greatly enhanced, while the r-process elements seem normal. We found its projected rotational velocity (vsini = 3.3 ± 0.1 km s-1) to be significantly higher than solar and incompatible with its isochrone-derived age. Radial velocity monitoring shows that the star has a binary companion. Conclusions. Based on the high s-process element enhancements and low beryllium abundance, we suggest that HIP 10725 has been polluted by mass transfer from an AGB star that probably had an initial mass of about 2 M⊙. The radial velocity variations suggest the presence of an unseen binary companion, probably the remnant of a former AGB star. Isochrones predict a solar-age star, but this disagrees with the high projected rotational velocity and high chromospheric activity. We conclude that HIP 10725 is a field blue straggler, rejuvenated by the mass-transfer process of its former AGB companion.

Published
2015

12. HIP 10725: The first solar twin/analogue field blue straggler

Author

Schirbel, Lucas, primary, Meléndez, Jorge, additional, Karakas, Amanda I., additional, Ramírez, Iván, additional, Castro, Matthieu, additional, Faria, Marcos A., additional, Lugaro, Maria, additional, Asplund, Martin, additional, Maia, Marcelo Tucci, additional, Yong, David, additional, Howes, Louise, additional, and do Nascimento, José D., additional

Published
2015
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13. On the metallicity dependence of the [Y/Mg]–age relation for solar-type stars.

Author

Feltzing, Sofia, Howes, Louise M., McMillan, Paul J., and Stonkutė, Edita

Subjects
*AGE of stars, *DWARF stars, *GALAXIES, *STELLAR parallax, *STELLAR activity, MEASUREMENT of age of stars
Abstract

Several recent studies of solar twins in the solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as elsewhere in the Galaxy, it would provide a very powerful tool to derive ages of stars without the need to resort to determining their masses (evolutionary stage) very precisely. The methodwould also likelywork if the stellar parameters have relatively large errors. The studies presented in the recent literature span a narrow range of [Fe/H]. By studying a larger sample of solar neighbourhood dwarfs with a much larger range of [Fe/H], we find that the relation between [Y/Mg] and age depends on the [Fe/H] of the stars. Hence, it appears that the [Y/Mg]–age relation is unique to solar analogues. [ABSTRACT FROM AUTHOR]

Published
2017
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14. 4MOST Survey Strategy Plan

Author

Guiglion, Guillaume, Battistini, Chiara, Bell, Cameron P. M., Bensby, Thomas, Boller, Thomas, Chiappini, Cristina, Comparat, Johan, Christlieb, Norbert, Church, Ross, Cioni, Maria-Rosa L., Davies, Luke, Dwelly, Tom, De Jong, Roelof S., Feltzing, Sofia, Gueguen, Alain, Howes, Louise, Irwin, Mike, Kushniruk, Iryna, Lam, Man I, Liske, Jochen, McMahon, Richard, Merloni, Andrea, Norberg, Peder, Robotham, Aaron S. G., Schnurr, Olivier, Sorce, Jenny G., Starkenburg, Else, Storm, Jesper, Swann, Elizabeth, Tempel, Elmo, Thi, Wing-Fai, Worley, C. Clare, Walcher, C. Jakob, and The 4MOST Collaboration

Subjects
010308 nuclear & particles physics, 0103 physical sciences, 010303 astronomy & astrophysics, 01 natural sciences
Abstract

The current status of and motivation for the 4MOST survey strategy, as developed by the Consortium science team, are presented here. Key elements of the strategy are described, such as sky coverage, number of visits and total exposure times in different parts of the sky, and how to deal with different observing conditions. The task of organising the strategy is not simple, with many different surveys that have vastly different target brightnesses and densities, sample completeness levels, and signal-to-noise requirements. We introduce here a number of concepts that we will use to ensure all surveys are optimised. Astronomers who are planning to submit a Participating Survey proposal are strongly encouraged to read this article and any relevant 4MOST Survey articles in this issue of The Messenger such that they can optimally complement and benefit from the planned surveys of the 4MOST Consortium., Published in The Messenger vol. 175, pp. 17-21, March 2019.

15. 4MOST Scientific Operations

Author

Walcher, C. Jakob, Banerji, Manda, Battistini, Chiara, Bell, Cameron P. M., Bellido-Tirado, Olga, Bensby, Thomas, Bestenlehner, Joachim M., Boller, Thomas, Brynnel, Joar, Casey, Andrew, Chiappini, Cristina, Christlieb, Norbert, Church, Ross, Cioni, Maria-Rosa L., Croom, Scott, Comparat, Johan, Davies, Luke J. M., De Jong, Roelof S., Dwelly, Tom, Enke, Harry, Feltzing, Sofia, Feuillet, Diane, Fouesneau, Morgan, Ford, Dominic, Frey, Steffen, Gonzalez-Solares, Eduardo, Gueguen, Alain, Howes, Louise, Irwin, Mike, Klar, Jochen, Kordopatis, Georges, Korn, Andreas, Krumpe, Mirko, Kushniruk, Iryna, Lam, Man I, Lewis, James, Lind, Karin, Liske, Jochen, Loveday, Jon, Mainieri, Vincenzo, Martell, Sarah, Matijevic, Gal, McMahon, Richard, Merloni, Andrea, Murphy, David, Niederhofer, Florian, Norberg, Peder, Pramskiy, Alexander, Romaniello, Martino, Robotham, Aaron S. G., Rothmaier, Florian, Ruchti, Gregory, Schnurr, Olivier, Schwope, Axel, Smedley, Scott, Sorce, Jenny, Starkenburg, Else, Stilz, Ingo, Storm, Jesper, Tempel, Elmo, Thi, Wing-Fai, Traven, Gregor, Valentini, Marica, Van Den Ancker, Mario, Walton, Nicholas, Winkler, Roland, and Worley, C. Clare

Subjects
010308 nuclear & particles physics, 0103 physical sciences, 010303 astronomy & astrophysics, 01 natural sciences
Abstract

The 4MOST instrument is a multi-object spectrograph that will address Galactic and extragalactic science cases simultaneously by observing targets from a large number of different surveys within each science exposure. This parallel mode of operation and the survey nature of 4MOST require some distinct 4MOST- specific operational features within the overall operations model of ESO. The main feature is that the 4MOST Consortium will deliver, not only the instrument, but also contractual services to the user community, which is why 4MOST is also described as a facility. This white paper concentrates on information particularly useful to answering the forthcoming Call for Letters of Intent., Published in The Messenger vol. 175, pp. 12-16, March 2019.

16. 4MOST: Project overview and information for the First Call for Proposals

Author

De Jong, Roelof S., Agertz, Oscar, Berbel, Alex Agudo, Aird, James, Alexander, David A., Amarsi, Anish, Anders, Friedrich, Andrae, Rene, Ansarinejad, Behzad, Ansorge, Wolfgang, Antilogus, Pierre, Anwand-Heerwart, Heiko, Arentsen, Anke, Arnadottir, Anna, Asplund, Martin, Auger, Matt, Azais, Nicolas, Baade, Dietrich, Baker, Gabriella, Baker, Sufyan, Balbinot, Eduardo, Baldry, Ivan K., Banerji, Manda, Barden, Samuel, Barklem, Paul, Barthélémy-Mazot, Eléonore, Battistini, Chiara, Bauer, Svend, Bell, Cameron P. M., Bellido-Tirado, Olga, Bellstedt, Sabine, Belokurov, Vasily, Bensby, Thomas, Bergemann, Maria, Bestenlehner, Joachim M., Bielby, Richard, Bilicki, Maciej, Blake, Chris, Bland-Hawthorn, Joss, Boeche, Corrado, Boland, Wilfried, Boller, Thomas, Bongard, Sebastien, Bongiorno, Angela, Bonifacio, Piercarlo, Boudon, Didier, Brooks, David, Brown, Michael J. I., Brown, Rebecca, Brüggen, Marcus, Brynnel, Joar, Brzeski, Jurek, Buchert, Thomas, Buschkamp, Peter, Caffau, Elisabetta, Caillier, Patrick, Carrick, Jonathan, Casagrande, Luca, Case, Scott, Casey, Andrew, Cesarini, Isabella, Cescutti, Gabriele, Chapuis, Diane, Chiappini, Cristina, Childress, Michael, Christlieb, Norbert, Church, Ross, Cioni, Maria-Rosa L., Cluver, Michelle, Colless, Matthew, Collett, Thomas, Comparat, Johan, Cooper, Andrew, Couch, Warrick, Courbin, Frederic, Croom, Scott, Croton, Darren, Daguisé, Eric, Dalton, Gavin, Davies, Luke J. M., Davis, Tamara, De Laverny, Patrick, Deason, Alis, Dionies, Frank, Disseau, Karen, Doel, Peter, Döscher, Daniel, Driver, Simon P., Dwelly, Tom, Eckert, Dominique, Edge, Alastair, Edvardsson, Bengt, Youssoufi, Dalal El, Elhaddad, Ahmed, Enke, Harry, Erfanianfar, Ghazaleh, Farrell, Tony, Fechner, Thomas, Feiz, Carmen, Feltzing, Sofia, Ferreras, Ignacio, Feuerstein, Dietrich, Feuillet, Diane, Finoguenov, Alexis, Ford, Dominic, Fotopoulou, Sotiria, Fouesneau, Morgan, Frenk, Carlos, Frey, Steffen, Gaessler, Wolfgang, Geier, Stephan, Fusillo, Nicola Gentile, Gerhard, Ortwin, Giannantonio, Tommaso, Giannone, Domenico, Gibson, Brad, Gillingham, Peter, González-Fernández, Carlos, Gonzalez-Solares, Eduardo, Gottloeber, Stefan, Gould, Andrew, Grebel, Eva K., Gueguen, Alain, Guiglion, Guillaume, Haehnelt, Martin, Hahn, Thomas, Hansen, Camilla J., Hartman, Henrik, Hauptner, Katja, Hawkins, Keith, Haynes, Dionne, Haynes, Roger, Heiter, Ulrike, Helmi, Amina, Aguayo, Cesar Hernandez, Hewett, Paul, Hinton, Samuel, Hobbs, David, Hoenig, Sebastian, Hofman, David, Hook, Isobel, Hopgood, Joshua, Hopkins, Andrew, Hourihane, Anna, Howes, Louise, Howlett, Cullan, Huet, Tristan, Irwin, Mike, Iwert, Olaf, Jablonka, Pascale, Jahn, Thomas, Jahnke, Knud, Jarno, Aurélien, Jin, Shoko, Jofre, Paula, Johl, Diana, Jones, Damien, Jönsson, Henrik, Jordan, Carola, Karovicova, Iva, Khalatyan, Arman, Kelz, Andreas, Kennicutt, Robert, King, David, Kitaura, Francisco, Klar, Jochen, Klauser, Urs, Kneib, Jean-Paul, Koch, Andreas, Koposov, Sergey, Kordopatis, Georges, Korn, Andreas, Kosmalski, Johan, Kotak, Rubina, Kovalev, Mikhail, Kreckel, Kathryn, Kripak, Yevgen, Krumpe, Mirko, Kuijken, Koen, Kunder, Andrea, Kushniruk, Iryna, Lam, Man I, Lamer, Georg, Laurent, Florence, Lawrence, Jon, Lehmitz, Michael, Lemasle, Bertrand, Lewis, James, Li, Baojiu, Lidman, Chris, Lind, Karin, Liske, Jochen, Lizon, Jean-Louis, Loveday, Jon, Ludwig, Hans-Günter, McDermid, Richard M., Maguire, Kate, Mainieri, Vincenzo, Mali, Slavko, Mandel, Holger, Mandel, Kaisey, Mannering, Liz, Martell, Sarah, Delgado, David Martinez, Matijevic, Gal, McGregor, Helen, McMahon, Richard, McMillan, Paul, Mena, Olga, Merloni, Andrea, Meyer, Martin J., Michel, Christophe, Micheva, Genoveva, Migniau, Jean-Emmanuel, Minchev, Ivan, Monari, Giacomo, Muller, Rolf, Murphy, David, Muthukrishna, Daniel, Nandra, Kirpal, Navarro, Ramon, Ness, Melissa, Nichani, Vijay, Nichol, Robert, Nicklas, Harald, Niederhofer, Florian, Norberg, Peder, Obreschkow, Danail, Oliver, Seb, Owers, Matt, Pai, Naveen, Pankratow, Sergei, Parkinson, David, Paschke, Jens, Paterson, Robert, Pecontal, Arlette, Parry, Ian, Phillips, Dan, Pillepich, Annalisa, Pinard, Laurent, Pirard, Jeff, Piskunov, Nikolai, Plank, Volker, Plüschke, Dennis, Pons, Estelle, Popesso, Paola, Power, Chris, Pragt, Johan, Pramskiy, Alexander, Pryer, Dan, Quattri, Marco, Queiroz, Anna Barbara De Andrade, Quirrenbach, Andreas, Rahurkar, Swara, Raichoor, Anand, Ramstedt, Sofia, Rau, Arne, Recio-Blanco, Alejandra, Reiss, Roland, Renaud, Florent, Revaz, Yves, Rhode, Petra, Richard, Johan, Richter, Amon David, Rix, Hans-Walter, Robotham, Aaron S. G., Roelfsema, Ronald, Romaniello, Martino, Rosario, David, Rothmaier, Florian, Roukema, Boudewijn, Ruchti, Gregory, Rupprecht, Gero, Rybizki, Jan, Ryde, Nils, Saar, Andre, Sadler, Elaine, Sahlén, Martin, Salvato, Mara, Sassolas, Benoit, Saunders, Will, Saviauk, Allar, Sbordone, Luca, Schmidt, Thomas, Schnurr, Olivier, Scholz, Ralf-Dieter, Schwope, Axel, Seifert, Walter, Shanks, Tom, Sheinis, Andrew, Sivov, Tihomir, Skúladóttir, Ása, Smartt, Stephen, Smedley, Scott, Smith, Greg, Smith, Robert, Sorce, Jenny, Spitler, Lee, Starkenburg, Else, Steinmetz, Matthias, Stilz, Ingo, Storm, Jesper, Sullivan, Mark, Sutherland, William, Swann, Elizabeth, Tamone, Amélie, Taylor, Edward N., Teillon, Julien, Tempel, Elmo, Ter Horst, Rik, Thi, Wing-Fai, Tolstoy, Eline, Trager, Scott, Traven, Gregor, Tremblay, Pier-Emmanuel, Tresse, Laurence, Valentini, Marica, Van De Weygaert, Rien, Van Den Ancker, Mario, Veljanoski, Jovan, Venkatesan, Sudharshan, Wagner, Lukas, Wagner, Karl, Walcher, C. Jakob, Waller, Lew, Walton, Nicholas, Wang, Lingyu, Winkler, Roland, Wisotzki, Lutz, Worley, C. Clare, Worseck, Gabor, Xiang, Maosheng, Xu, Wenli, Yong, David, Zhao, Cheng, Zheng, Jessica, Zscheyge, Florian, and Zucker, Daniel

Subjects
010308 nuclear & particles physics, 0103 physical sciences, 010303 astronomy & astrophysics, 01 natural sciences
Abstract

We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations., Published in The Messenger vol. 175, pp. 3-11, March 2019.

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