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  • 1
    Online Resource
    Online Resource
    Cosmic dynamics in the era of Extremely Large Telescopes
    Oxford University Press (OUP) ; 2008
    In:  Monthly Notices of the Royal Astronomical Society Vol. 386, No. 3 ( 2008-05), p. 1192-1218
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 386, No. 3 ( 2008-05), p. 1192-1218
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1111/j.1365-2966.2008.13090.x
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2008
    detail.hit.zdb_id: 2016084-7
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  • 2
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    CODEX: measuring the acceleration of the universe and beyond
    Cambridge University Press (CUP) ; 2005
    In:  Proceedings of the International Astronomical Union Vol. 1, No. S232 ( 2005-11), p. 193-197
    Details
    In: Proceedings of the International Astronomical Union, Cambridge University Press (CUP), Vol. 1, No. S232 ( 2005-11), p. 193-197
    Type of Medium: Online Resource
    ISSN: 1743-9213 , 1743-9221
    URL: Article
    DOI: 10.1017/S1743921306000482
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2005
    detail.hit.zdb_id: 2170724-8
    SSG: 16,12
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  • 3
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    The clustering properties of the Lyman   clouds
    Oxford University Press (OUP) ; 1997
    In:  Monthly Notices of the Royal Astronomical Society Vol. 285, No. 1 ( 1997-02-11), p. 209-217
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 285, No. 1 ( 1997-02-11), p. 209-217
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/285.1.209
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 1997
    detail.hit.zdb_id: 2016084-7
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  • 4
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    The absorption spectrum of the QSO PKS $\bf 2126-158$ (${z}_{\bf em}\bf =3.27$) at high resolution
    EDP Sciences ; 1998
    In:  Astronomy and Astrophysics Supplement Series Vol. 127, No. 2 ( 1998-01), p. 217-232
    Details
    In: Astronomy and Astrophysics Supplement Series, EDP Sciences, Vol. 127, No. 2 ( 1998-01), p. 217-232
    Type of Medium: Online Resource
    ISSN: 0365-0138 , 1286-4846
    URL: Article
    DOI: 10.1051/aas:1998104
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 1495579-9
    SSG: 12
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  • 5
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    XQR-30: The ultimate XSHOOTER quasar sample at the reionization epoch
    Oxford University Press (OUP) ; 2023
    In:  Monthly Notices of the Royal Astronomical Society Vol. 523, No. 1 ( 2023-05-23), p. 1399-1420
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 523, No. 1 ( 2023-05-23), p. 1399-1420
    Abstract: The final phase of the reionization process can be probed by rest-frame UV absorption spectra of quasars at z ≳ 6, shedding light on the properties of the diffuse intergalactic medium within the first Gyr of the Universe. The ESO Large Programme ‘XQR-30: the ultimate XSHOOTER legacy survey of quasars at z ≃ 5.8–6.6’ dedicated ∼250 h of observations at the VLT to create a homogeneous and high-quality sample of spectra of 30 luminous quasars at z ∼ 6, covering the rest wavelength range from the Lyman limit to beyond the Mg ii emission. Twelve quasar spectra of similar quality from the XSHOOTER archive were added to form the enlarged XQR-30 sample, corresponding to a total of ∼350 h of on-source exposure time. The median effective resolving power of the 42 spectra is R ≃ 11 400 and 9800 in the VIS and NIR arm, respectively. The signal-to-noise ratio per 10 km s−1 pixel ranges from ∼11 to 114 at λ ≃ 1285 Å rest frame, with a median value of ∼29. We describe the observations, data reduction, and analysis of the spectra, together with some first results based on the E-XQR-30 sample. New photometry in the H and K bands are provided for the XQR-30 quasars, together with composite spectra whose characteristics reflect the large absolute magnitudes of the sample. The composite and the reduced spectra are released to the community through a public repository, and will enable a range of studies addressing outstanding questions regarding the first Gyr of the Universe.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/stad1468
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2016084-7
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  • 6
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    ESPRESSO at VLT : On-sky performance and first results
    EDP Sciences ; 2021
    In:  Astronomy & Astrophysics Vol. 645 ( 2021-01), p. A96-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 645 ( 2021-01), p. A96-
    Abstract: Context. ESPRESSO is the new high-resolution spectrograph of ESO’s Very Large Telescope (VLT). It was designed for ultra-high radial-velocity (RV) precision and extreme spectral fidelity with the aim of performing exoplanet research and fundamental astrophysical experiments with unprecedented precision and accuracy. It is able to observe with any of the four Unit Telescopes (UTs) of the VLT at a spectral resolving power of 140 000 or 190 000 over the 378.2 to 788.7 nm wavelength range; it can also observe with all four UTs together, turning the VLT into a 16 m diameter equivalent telescope in terms of collecting area while still providing a resolving power of 70 000. Aims. We provide a general description of the ESPRESSO instrument, report on its on-sky performance, and present our Guaranteed Time Observation (GTO) program along with its first results. Methods. ESPRESSO was installed on the Paranal Observatory in fall 2017. Commissioning (on-sky testing) was conducted between December 2017 and September 2018. The instrument saw its official start of operations on October 1, 2018, but improvements to the instrument and recommissioning runs were conducted until July 2019. Results. The measured overall optical throughput of ESPRESSO at 550 nm and a seeing of 0.65″ exceeds the 10% mark under nominal astroclimatic conditions. We demonstrate an RV precision of better than 25 cm s −1 during a single night and 50 cm s −1 over several months. These values being limited by photon noise and stellar jitter shows that the performance is compatible with an instrumental precision of 10 cm s −1 . No difference has been measured across the UTs, neither in throughput nor RV precision. Conclusions. The combination of the large collecting telescope area with the efficiency and the exquisite spectral fidelity of ESPRESSO opens a new parameter space in RV measurements, the study of planetary atmospheres, fundamental constants, stellar characterization, and many other fields.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202038306
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 7
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    Revisiting Proxima with ESPRESSO
    EDP Sciences ; 2020
    In:  Astronomy & Astrophysics Vol. 639 ( 2020-7), p. A77-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 639 ( 2020-7), p. A77-
    Abstract: Context. The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet. Aims. We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision. Methods. We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s −1 . We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals. Results. We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13 M ⊕ . In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086 M ⊕ . We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s −1 . If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08 M ⊕ . We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6 M ⊕ at periods shorter than 50 days.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202037745
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 8
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    ESPRESSO high-resolution transmission spectroscopy of WASP-76 b
    EDP Sciences ; 2021
    In:  Astronomy & Astrophysics Vol. 646 ( 2021-2), p. A158-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 646 ( 2021-2), p. A158-
    Abstract: Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly irradiated, ultra-hot Jupiter-sized planet, WASP-76b. We investigated the presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R ≈ 140 000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800–7880 Å) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows ‘wiggles’, which are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li  I , Na  I , Mg  I , Ca  II , Mn  I , K  I , and Fe  I . All are detected with a confidence level between 9.2 σ (Na  I ) and 2.8 σ (Mg  I ). We did not detect the following species: Ti  I , Cr  I , Ni  I , TiO, VO, and ZrO. We impose the following 1 σ upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li  I on WASP-76b for the first time. In addition, we confirm the presence of Na  I and Fe  I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~0.1% in the transmission spectrum and ~10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202039511
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 9
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    A precise architecture characterization of the π Mensae planetary system
    EDP Sciences ; 2020
    In:  Astronomy & Astrophysics Vol. 642 ( 2020-10), p. A31-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 642 ( 2020-10), p. A31-
    Abstract: Context. The bright star π Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory’s Very Large Telescope. The star hosts a multi-planet system (a transiting 4 M ⊕ planet at ~0.07 au and a sub-stellar companion on a ~2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization. Aims. With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. We also take advantage of the new photometric transits of π Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign. Methods. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with H IPPARCOS and Gaia . We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters. Results. We present a precise characterization of the planetary system around π Men. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s −1 ) allow for a precise retrieval of the Doppler signal induced by π Men c. The residuals show a root mean square of 1.2 m s −1 , which is half that of the HARPS data; based on the residuals, we put limits on the presence of additional low-mass planets (e.g. we can exclude companions with a minimum mass less than ~2 M ⊕ within the orbit of π Men c). We improve the ephemeris of π Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of π Men b with high precision ( i b =45.8 −1.1 +1.4 deg). This leads to the precise measurement of its absolute mass m b =14.1 −0.4 +0.5 M Jup , indicating that π Men b can be classified as a brown dwarf. Conclusions. The π Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. Our determination of the 3D architecture of the π Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The accurate measurement of the mass of π Men b contributes to make the brown dwarf desert a bit greener.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202038416
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 10
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    Characterization of the K2-38 planetary system : Unraveling one of the densest planets known to date
    EDP Sciences ; 2020
    In:  Astronomy & Astrophysics Vol. 641 ( 2020-9), p. A92-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 641 ( 2020-9), p. A92-
    Abstract: Context. An accurate characterization of the known exoplanet population is key to understanding the origin and evolution of planetary systems. Determining true planetary masses through the radial velocity (RV) method is expected to experience a great improvement thanks to the availability of ultra-stable echelle spectrographs. Aims. We took advantage of the extreme precision of the new-generation echelle spectrograph ESPRESSO to characterize the transiting planetary system orbiting the G2V star K2-38 located at 194 pc from the Sun with V ~ 11.4. This system is particularly interesting because it could contain the densest planet detected to date. Methods. We carried out a photometric analysis of the available K2 photometric light curve of this star to measure the radius of its two known planets, K2-38b and K2-38c, with P b = 4.01593 ± 0.00050 d and P c = 10.56103 ± 0.00090 d, respectively. Using 43 ESPRESSO high-precision RV measurements taken over the course of 8 months along with the 14 previously published HIRES RV measurements, we modeled the orbits of the two planets through a Markov chain Monte Carlo analysis, significantly improving their mass measurements. Results. Using ESPRESSO spectra, we derived the stellar parameters, T eff = 5731 ± 66, log g = 4.38 ± 0.11 dex, and [Fe/H] = 0.26 ± 0.05 dex, and thus the mass and radius of K2-38, M ⋆ = 1.03 −0.02 +0.04 M ⊕ and R ⋆ = 1.06 −0.06 +0.09 R ⊕ . We determine new values for the planetary properties of both planets. We characterize K2-38b as a super-Earth with R P = 1.54 ± 0.14 R ⊕ and M p = 7.3 −1.0 +1.1 M ⊕ , and K2-38c as a sub-Neptune with R P = 2.29 ± 0.26 R ⊕ and M p = 8.3 −1.3 +1.3 M ⊕ . Combining the radius and mass measurements, we derived a mean density of ρ p = 11.0 −2.8 +4.1 g cm −3 for K2-38b and ρ p = 3.8 −1.1 +1.8 g cm −3 for K2-38c, confirming K2-38b as one of the densest planets known to date. Conclusions. The best description for the composition of K2-38b comes from an iron-rich Mercury-like model, while K2-38c is better described by a rocky-model with H2 envelope. The maximum collision stripping boundary shows how giant impacts could be the cause for the high density of K2-38b. The irradiation received by each planet places them on opposite sides of the radius valley. We find evidence of a long-period signal in the RV time-series whose origin could be linked to a 0.25–3 M J planet or stellar activity.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202038187
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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