Examinando por Autor "Micela, G."
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Ítem ESPRESSO highlights the binary nature of the ultra-metal-poor giant HE 0107-5240(EDP Sciences, 2020) Bonifacio, P.; Molaro, P.; Adibekyan, V.; Aguado, D.; Alibert, Y.; Allende Prieto, C.; Caffau, E.; Cristiani, S.; Cupani, G.; Marcantonio, P.; D'Odorico, D.; Ehrenreich, D.; Figueira, P.; Genova, R.; González Hernández, J.; Lo Curto, G.; Lovis, C.; Martins, C.; Mehner, A.; Micela, G.; Monaco, L.; Nunes, N.; Pepe, F.; Poretti, E.; Rebolo, R.; Santos, N.; Saviane, I.; Sousa, S.; Sozzetti, A.; Suarez-Mascareño, A.; Udry, S.; Zapatero-Osorio, M.Context. The vast majority of the known stars of ultra low metallicity ([Fe=H] >-4:5) are known to be enhanced in carbon, and belong to the 'low-carbon band' (A(C) = log(C=H) + 12 7:6). It is generally, although not universally, accepted that this peculiar chemical composition reflects the chemical composition of the gas cloud out of which these stars were formed. The first ultra-metalpoor star discovered, HE 0107-5240, is also enhanced in carbon and belongs to the 'low-carbon band'. It has recently been claimed to be a long-period binary, based on radial velocity measurements. It has also been claimed that this binarity may explain its peculiar composition as being due to mass transfer from a former AGB companion. Theoretically, low-mass ratios in binary systems are much more favoured amongst Pop III stars than they are amongst solar-metallicity stars. Any constraint on the mass ratio of a system of such low metallicity would shed light on the star formation mechanisms in this metallicity regime. Aims.We acquired one high precision spectrum withESPRESSO in order to check the reality of the radial velocity variations. In addition we analysed all the spectra of this star in the ESO archive obtained with UVES to have a set of homogenously measured radial velocities. Methods. The radial velocities were measured using cross correlation against a synthetic spectrum template. Due to the weakness of metallic lines in this star, the signal comes only from the CH molecular lines of the G-band. Results. The measurement obtained in 2018 from an ESPRESSO spectrum demonstrates unambiguously that the radial velocity of HE 0107-5240 has increased from 2001 to 2018. Closer inspection of the measurements based on UVES spectra in the interval 2001-2006 show that there is a 96% probability that the radial velocity correlates with time, hence the radial velocity variations can already be suspected from the UVES spectra alone. Conclusions.We confirm the earlier claims of radial velocity variations in HE0107-5240. The simplest explanation of such variations is that the star is indeed in a binary system with a long period. The nature of the companion is unconstrained and we consider it is equally probable that it is an unevolved companion or a white dwarf. Continued monitoring of the radial velocities of this star is strongly encouraged.Ítem Gaia-ESO Survey: Gas dynamics in the Carina nebula through optical emission lines(EDP SCIENCES, 2016-06) Damiani, F.; Bonito, R.; Magrini, L.; Prisinzano, L.; Mapelli, M.; Micela, G.; Kalari, V.; Maíz Apellániz, J.; Gilmore, G.; Randich, S.; Alfaro, E.; Flaccomio, E.; Koposov, S.; Klutsch, A.; Lanzafame, A. C.; Pancino, E.; Sacco, G. G.; Bayo, A.; Carraro, G.; Casey, A. R.; Costado, M. T.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Worley, C.; Zaggia, S.; Zwitter, T.; Dorda, R.Aims. We present observations from the Gaia-ESO Survey in the lines of Hα, [N II], [S II], and He I of nebular emission in the central part of the Carina nebula. Methods. We investigate the properties of the two already known kinematic components (approaching and receding), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV >50 km s-1) gas emission. Results. We show that gas giving rise to Hα and He I emission is dynamically well correlated with but not identical to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arise from several distinct shell-like expanding regions, the most evident found around η Car, the Trumpler 14 core, and the star WR25. These “shells” are non-spherical and show distortions probably caused by collisions with other shells or colder, higher-density gas. Some of them are also partially obscured by foreground dust lanes, while very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from η Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of Hα are found to arise from expanding dust reflecting the η Car spectrum.Ítem The Gaia -ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities(EDP Sciences, 2015-08) Jackson, R.J.; Jeffries, R.D.; Lewis, J.; Koposov, S.E.; Sacco, G.G.; Randich, S.; Asplund, M.; Binney, J.; Bonifacio, P.; Drew, J.E.; Feltzing, S.; Ferguson, A.M.N.; Micela, G.; Neguerela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Alfaro, E.J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.; Irwin, M.; Korn, A.J.; Lanzafame, A.C.; Pancino, E.; Recio-Blanco, A.; Smiljanic, R.; Van Eck, S.; Walton, N.; Bayo, A.; Bergemann, M.; Carraro, G.; Costado, M.T.; Damiani, Edvardsson B.; Franciosini, E.; Frasca, A.; Heiter, U.; Hill, V.; Hourihane, A.; Jofré, P.; Lardo, C.; De Laverny, P.; Lind, K.; Magrini, L.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Prisinzano, L.; Sbordone, L.; Sousa, S.G.; Worley, C.C.; Zaggia, S.Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope. Aims. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (v sin i) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. Methods. We present an analysis to empirically quantify the size and distribution of uncertainties in RV and v sin i using spectra from repeated exposures of the same stars. Results. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and v sin i, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Student's t-distributions than by normal distributions. Conclusions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the v sin i precision for stars in young clusters, as a function of S/N, v sin i and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22-0.26 kms-1, dependent on instrumental configuration. © ESO, 2015.Ítem The Gaia -ESO Survey: Lithium measurements and new curves of growth(EDP Sciences, 2022-12-01) Franciosini, E.; Randich, S.; De Laverny, P.; Biazzo, K.; Feuillet, D.K.; Frasca, A.; Lind, K.; Prisinzano, L.; Tautvaišiene, G.; Lanzafame, A.C.; Smiljanic, R.; Gonneau, A.; Magrini, L.; Pancino, E.; Guiglion, G.; Sacco, G.G.; Sanna, N.; Gilmore, G.; Bonifacio, P.; Jeffries, R.D.; Micela, G.; Prusti, T.; Alfaro, E.J.; Bensby, T.; Bragaglia, A.; François, P.; Korn, A.J.; Van Eck, S.; Bayo, A.; Bergemann, M.; Carraro, G.; Heiter, U.; Hourihane, A.; Jofré, P.; Lewis, J.; Martayan, C.; Monaco, L.; Morbidelli, L.; Worley, C.C.; Zaggia, S.Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey that was carried out using the multi-object FLAMES spectrograph at the Very Large Telescope. The survey provides accurate radial velocities, stellar parameters, and elemental abundances for ~115 000 stars in all Milky Way components. Aims. In this paper, we describe the method adopted in the final data release to derive lithium equivalent widths (EWs) and abundances. Methods. Lithium EWs were measured using two different approaches for FGK and M-type stars, to account for the intrinsic differences in the spectra. For FGK stars, we fitted the lithium line using Gaussian components, while direct integration over a predefined interval was adopted for M-type stars. Care was taken to ensure continuity between the two regimes. Abundances were derived using a new set of homogeneous curves of growth that were derived specifically for GES, and which were measured on a synthetic spectral grid consistently with the way the EWs were measured. The derived abundances were validated by comparison with those measured by other analysis groups using different methods. Results. Lithium EWs were measured for ~40 000 stars, and abundances could be derived for ~38 000 of them. The vast majority of the measures (80%) have been obtained for stars in open cluster fields. The remaining objects are stars in globular clusters, or field stars in the Milky Way disc, bulge, and halo. Conclusions. The GES dataset of homogeneous lithium abundances described here will be valuable for our understanding of several processes, from stellar evolution and internal mixing in stars at different evolutionary stages to Galactic evolution. © 2022 EDP Sciences. All rights reserved.Ítem The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy(EDP Sciences, 2022-10-01) Randich, S.; Gilmore, G.; Magrini, L.; Sacco, G.G.; Jackson, R.J.; Jeffries, R.D.; Worley, C.C.; Hourihane, A.; Gonneau, A.; Viscasillas Vázquez, C.; Franciosini, E.; Lewis, J.R.; Alfaro, E.J.; Allende Prieto, C.; Bensby, T.; Blomme, R.; Bragaglia, A.; Flaccomio, E.; François, P.; Irwin, M.J.; Koposov, S.E.; Korn, A.J.; Lanzafame, A.C.; Pancino, E.; Recio Blanco, A.; Smiljanic, R.; Van Eck, S.; Zwitter, T.; Asplund, M.; Bonifacio, P.; Feltzing, S.; Binney, J.; Drew, J.; Ferguson, A.M.N.; Micela, G.; Negueruela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Bayo, A.; Bergemann, M.; Biazzo, K.; Carraro, G.; Casey, A.R.; Damiani, F.; Frasca, A.; Heiter, U.; Hill, V.; Jofré, P.; de Laverny, P.; Lind, K.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone, L.; Sousa, S.G.; Zaggia, S.; Adibekyan, V.; Bonito, R.; Caffau, E.; Daflon, S.; Feuillet, D.K.; Gebran, M.; González Hernández, J.I.; Guiglion, G.; Herrero, A.; Lobel, A.; Maíz Apellániz, J.; Merle, T.; Mikolaitis, S.; Montes, D.; Morel, T.; Soubiran, C.; Spina, L.; Tabernero, H.M.; Tautvaišiene, G.; Traven, G.; Valentini, M.; Van der Swaelmen, M.; Villanova, S.; Wright, N.J.; Abbas, U.; Aguirre Børsen-Koch, V.; Alves, J.; Balaguer Núnez, L.; Barklem, P.S.; Barrado, D.; Berlanas, S.R.; Binks, A.S.; Bressan, A.; Capuzzo Dolcetta, R.; Casagrande, L.; Casamiquela, L.; Collins, R.S.; D’Orazi, V.; Dantas, M.L.L.; Debattista, V.P.; Delgado Mena, E.; Di Marcantonio, P.; Drazdauskas, A.; Evans, N.W.; Famaey, B.; Franchini, M.; Frémat, Y.; Friel, E.D.; Fu, X.; Geisler, D.; Gerhard, O.; González Solares, E.A.; Grebel, E.K.; Gutiérrez Albarrán, M.L.; Hatzidimitriou, D.; Held, E.V.; Jiménez Esteban, F.; Jönsson, H.; Jordi, C.; Khachaturyants, T.; Kordopatis, G.; Kos, J.; Lagarde, N.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S.L.; Messina, S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.; Monteiro, M.J.P.F.G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.; Murphy, D.N.A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palous, J.; Paunzen, E.; Pickering, J.C.; Quirrenbach, A.; Re Fiorentin, P.; Read, J.I.; Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G.M.; Spagna, A.; Steinmetz, M.; Stonkuté, E.; Sutorius, E.; Thévenin, F.; Tosi, M.; Tsantaki, M.; Vink, J.S.; Wright, N.; Wyse, R.F.G.; Zoccali, M.; Zorec, J.; Zucker, D.B.; Walton, N.A.Context. In the last 15 years different ground-based spectroscopic surveys have been started (and completed) with the general aim of delivering stellar parameters and elemental abundances for large samples of Galactic stars, complementing Gaia astrometry. Among those surveys, the Gaia-ESO Public Spectroscopic Survey, the only one performed on a 8m class telescope, was designed to target 100 000 stars using FLAMES on the ESO VLT (both Giraffe and UVES spectrographs), covering all the Milky Way populations, with a special focus on open star clusters. Aims. This article provides an overview of the survey implementation (observations, data quality, analysis and its success, data products, and releases), of the open cluster survey, of the science results and potential, and of the survey legacy. A companion article reviews the overall survey motivation, strategy, Giraffe pipeline data reduction, organisation, and workflow. Methods. We made use of the information recorded and archived in the observing blocks; during the observing runs; in a number of relevant documents; in the spectra and master catalogue of spectra; in the parameters delivered by the analysis nodes and the working groups; in the final catalogue; and in the science papers. Based on these sources, we critically analyse and discuss the output and products of the Survey, including science highlights. We also determined the average metallicities of the open clusters observed as science targets and of a sample of clusters whose spectra were retrieved from the ESO archive. Results. The Gaia-ESO Survey has determined homogeneous good-quality radial velocities and stellar parameters for a large fraction of its more than 110 000 unique target stars. Elemental abundances were derived for up to 31 elements for targets observed with UVES. Lithium abundances are delivered for about 1/3 of the sample. The analysis and homogenisation strategies have proven to be successful; several science topics have been addressed by the Gaia-ESO consortium and the community, with many highlight results achieved. Conclusions. The final catalogue will be released through the ESO archive in the first half of 2022, including the complete set of advanced data products. In addition to these results, the Gaia-ESO Survey will leave a very important legacy, for several aspects and for many years to come. © ESO 2022.Ítem The Gaia-ESO Public Spectroscopic Survey: Motivation, implementation, GIRAFFE data processing, analysis, and final data products?(EDP Sciences, 2022-10-01) Gilmore, G.; Randich, S.; Worley, C.C.; Hourihane, A.; Gonneau, A.; Sacco, G.G.; Lewis, J.R.; Magrini, L.; François, P.; Jeffries, R.D.; Koposov, S.E.; Bragaglia, A.; Alfaro, E.J.; Allende Prieto, C.; Blomme, R.; Korn, A.J.; Lanzafame, A.C.; Pancino, E.; Recio Blanco, A.; Smiljanic, R.; Van Eck, S.; Zwitter, T.; Bensby, T.; Flaccomio, E.; Irwin, M.J.; Franciosini, E.; Morbidelli, L.; Damiani, F.; Bonito, R.; Friel, E.D.; Vink, J.S.; Prisinzano, L.; Abbas, U.; Hatzidimitriou, D.; Held, E.V.; Jordi, C.; Paunzen, E.; Spagna, A.; Jackson, R.J.; Maíz Apellániz, J.; Asplund, M.; Bonifacio, P.; Feltzing, S.; Binney, J.; Drew, J.; Ferguson, A.M.N.; Micela, G.; Negueruela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Bergemann, M.; Casey, A.R.; Laverny, P.; Frasca, A.; Hill, V.; Lind, K.; Sbordone, L.; Sousa, S.G.; Adibekyan, V.; Caffau, E.; Daflon, S.; Feuillet, D.K.; Gebran, M.; González Hernández, J.I.; Guiglion, G.; Herrero, A.; Lobel, A.; Merle, T.; Mikolaitis, S.; Montes, D.; Morel, T.; Ruchti, G.; Soubiran, C.; Tabernero, H.M.; Tautvaišiene, G.; Traven, G.; Valentini, M.; Van der Swaelmen, M.; Villanova, S.; Viscasillas Vázquez, C.; Bayo, A.; Biazzo, K.; Carraro, G.; Edvardsson, B.; Heiter, U.; Jofré, P.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Walton, N.A.; Zaggia, S.; Aguirre Børsen-Koch, V.; Alves, J.; Balaguer Núnez, L.; Barklem, P.S.; Barrado, D.; Bellazzini, M.; Berlanas, S.R.; Binks, A.S.; Bressan, A.; Capuzzo Dolcetta, R.; Casagrande, L.; Casamiquela, L.; Collins, R.S.; D’Orazi, V.; Dantas, M.L.L.; Debattista, V.P.; Delgado Mena, E.; Marcantonio, P. Di; Drazdauskas, A.; Evans, N.W.; Famaey, B.; Franchini, M.; Frémat, Y.; Fu, X.; Geisler, D.; Gerhard, O.; González Solares, E.A.; Grebel, E.K.; Albarrán Gutiérrez, M.L.; Jiménez Esteban, F.; Jönsson, H.; Khachaturyants, T.; Kordopatis, G.; Kos, J.; Lagarde, N.; Ludwig, H.-G.; Mahy, L.; Mapelli, M.; Marfil, E.; Martell, S.L.; Messina, S.; Miglio, A.; Minchev, I.; Moitinho, A.; Montalban, J.; Monteiro, M.J.P.F.G.; Morossi, C.; Mowlavi, N.; Mucciarelli, A.; Murphy, D.N.A.; Nardetto, N.; Ortolani, S.; Paletou, F.; Palous, J.; Pickering, J.C.; Quirrenbach, A.; Re Fiorentin, P.; Read, J.I.; Romano, D.; Ryde, N.; Sanna, N.; Santos, W.; Seabroke, G.M.; Spina, L.; Steinmetz, M.; Stonkuté, E.; Sutorius, E.; Thévenin, F.; Tosi, M.; Tsantaki, M.; Wright, N.; Wyse, R.F.G.; Zoccali, M.; Zorec, J.; Zucker, D.B.Context. The Gaia-ESO Public Spectroscopic Survey is an ambitious project designed to obtain astrophysical parameters and elemental abundances for 100 000 stars, including large representative samples of the stellar populations in the Galaxy, and a well-defined sample of 60 (plus 20 archive) open clusters. We provide internally consistent results calibrated on benchmark stars and star clusters, extending across a very wide range of abundances and ages. This provides a legacy data set of intrinsic value, and equally a large wide-ranging dataset that is of value for the homogenisation of other and future stellar surveys and Gaia’s astrophysical parameters. Aims. This article provides an overview of the survey methodology, the scientific aims, and the implementation, including a description of the data processing for the GIRAFFE spectra. A companion paper introduces the survey results. Methods. Gaia-ESO aspires to quantify both random and systematic contributions to measurement uncertainties. Thus, all available spectroscopic analysis techniques are utilised, each spectrum being analysed by up to several different analysis pipelines, with considerable effort being made to homogenise and calibrate the resulting parameters. We describe here the sequence of activities up to delivery of processed data products to the ESO Science Archive Facility for open use. Results. The Gaia-ESO Survey obtained 202 000 spectra of 115 000 stars using 340 allocated VLT nights between December 2011 and January 2018 from GIRAFFE and UVES. Conclusions. The full consistently reduced final data set of spectra was released through the ESO Science Archive Facility in late 2020, with the full astrophysical parameters sets following in 2022. A companion article reviews the survey implementation, scientific highlights, the open cluster survey, and data products. © G. Gilmore et al. 2022.Ítem The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?(EDP Sciences, 2016-05) Bouvier, J.; Lanzafame, A.C.; Venuti, L.; Klutsch, A.; Jeffries, R.; Frasca, A.; Moraux, E.; Biazzo, K.; Messina, S.; Micela, G.; Randich, S.; Stauffer, J.; Cody, A.M.; Flaccomio, E.; Gilmore, G.; Bayo, A.; Bensby, T.; Bragaglia, A.; Carraro, G.; Casey, A.; Costado, M.T.; Damiani, F.; Delgado Mena, E.; Donati, P.; Franciosini, E.; Hourihane, A.; Koposov, S.; Lardo, C.; Lewis, J.; Magrini, L.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Sbordone, L.; Sousa, S.G.; Vallenari, A.; Worley, C.C.; Zaggia, S.; Zwitter, T.Context. The evolution of lithium abundance in cool dwarfs provides a unique probe of nonstandard processes in stellar evolution. Aims. We investigate the lithium content of young low-mass stars in the 5 Myr old, star forming region NGC 2264 and its relationship with rotation. Methods. We combine lithium equivalent width measurements (EW(Li)) from the Gaia-ESO Survey with the determination of rotational periods from the CSI 2264 survey. We only consider bona fide nonaccreting cluster members to minimize the uncertainties on EW(Li). Results. We report the existence of a relationship between lithium content and rotation in NGC 2264 at an age of 5 Myr. The Li-rotation connec tion is seen over a restricted temperature range (Teff = 3800–4400 K), where fast rotators are Li-rich compared to slow rotators. This correlation is similar to, albeit of lower amplitude than, the Li-rotation connection previously reported for K dwarfs in the 125 Myr old Pleiades cluster. We investigate whether the nonstandard pre-main-sequence models developed so far to explain the Pleiades results, which are based on episodic accre tion, pre-main-sequence, core-envelope decoupling, and/or radius inflation due to enhanced magnetic activity, can account for early development of the Li-rotation connection. While radius inflation appears to be the most promising possibility, each of these models has issues. We therefore also discuss external causes that might operate during the first few Myr of pre-main-sequence evolution, such as planet engulfment and/or steady disk accretion, as possible candidates for the common origin for Li excess and fast rotation in young low-mass pre-main-sequence stars. Conclusions. The emergence of a connection between lithium content and rotation rate at such an early age as 5 Myr suggests a complex link between accretion processes, early angular momentum evolution, and possibly planet formation, which likely impacts early stellar evolution and has yet to be fully deciphered.Ítem The Gaia-ESO Survey: pre-main-sequence stars in the young open cluster NGC 3293(OXFORD UNIV PRESS, 2016-05) Delgado, A. J.; Sampedro, L.; Alfaro, E. J.; Costado, M. T.; Yun, J. L.; Frasca, A.; Lanzafame, A. C.; Drew, J. E.; Eislöffel, J.; Blomme, R.; Morel, T.; Lobel, A.; Semaan, T.; Randich, S.; Jeffries, R. D.; Micela, G.; Vallenari, A.; Kalari, V.; Gilmore, G.; Flaccomio, E.; Carraro, G.; Lardo, C.; Monaco, L.; Prisinzano, L.; Sousa, S. G.; Morbidelli, L.; Lewis, J.; Koposov, S.; Hourihane, A.; Worley, C.; Casey, A.; Franciosini, E.; Sacco, G.; Magrini, L.The young open cluster NGC3293 is included in the observing program of the Gaia-ESO survey (GES). The radial velocity values provided have been used to assign cluster membership probabilities by means of a single-variable parametric analysis. These membership probabilities are compared to the results of the photometric membership assignment of NGC3293, based on UBVRI photometry. The agreement of the photometric and kinematic member samples amounts to 65 per cent, and could increase to 70 per cent as suggested by the analysis of the differences between both samples. A number of photometric PMS candidate members of spectral type F are found, which are confirmed by the results from VPHAS photometry and SED fitting for the stars in common with VPHAS and GES data sets. Excesses at mid- and near-infrared wavelengths, and signs of Hα emission, are investigated for them. Marginal presence of Hα emission or infilling is detected for the candidate members. Several of them exhibit moderate signs of U excess and weak excesses at mid-IR wavelengths. We suggest that these features originate from accretion discs in their last stages of evolution.