2025
Authors
Winterhalder, TO; Kammerer, J; Lacour, S; Mérand, A; Nowak, M; Stolker, T; Balmer, WO; Marleau, GD; Abuter, R; Amorim, A; Asensio-Torres, R; Berger, JP; Beust, H; Blunt, S; Bonnefoy, M; Bonnet, H; Bordoni, MS; Bourdarot, G; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Davies, R; Dembet, R; Dexter, J; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Lopez, RG; Gardner, T; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Grant, S; Haubois, X; el, GH; Henning, T; Hinkley, S; Hippler, S; Houlle, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Kurtovic, NT; Lagrange, AM; Lapeyrere, V; Le Bouquin, JB; Lutz, D; Maire, AL; Mang, F; Molliere, P; Mordasi, C; Mouillet, D; Nasedkin, E; Ott, T; Otten, GPPL; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Pourre, N; Pueyo, L; Ribeiro, D; Rickman, E; Rustamkulov, Z; Shangguan, J; Shimizu, T; Sing, D; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; van Dishoeck, EF; Vigan, A; Vincent, F; von Fellenberg, SD; Wang, JJ; Widmann, F; Woillez, J; Yazici, S; GRAVITY Collaboration;
Publication
ASTRONOMY & ASTROPHYSICS
Abstract
Context. Inferring the likely formation channel of giant exoplanets and brown dwarf companions from orbital and atmospheric observables remains a formidable challenge. Further and more precise directly measured dynamical masses of these companions are required to inform and gauge formation, evolutionary, and atmospheric models. We present an updated study of the recently discovered companion to HIP 99770 based on observations conducted with the near-infrared interferometer VLTI/GRAVITY.Aims. Through renewed orbital and spectral analyses based on the GRAVITY data, we characterise HIP 99770 b to better constrain its orbit, dynamical mass, and atmospheric properties, as well as to shed light on its likely formation channel.Methods. Upon inclusion of the new high-precision astrometry epoch, we ran an orbit fit to further constrain the dynamical mass of the companion and the orbit solution. We also analysed the GRAVITY K-band spectrum, placing it into context with literature data, and extracting magnitude, age, spectral type, bulk properties and atmospheric characteristics of HIP 99770 b.Results. We detected the companion at a radial separation of 417 mas from its host. The new orbit fit yields a dynamical mass of 17-5+6 MJup and an eccentricity of 0.31-0.12+0.06. We also find that additional relative astrometry epochs in the future will not enable further constraints on the dynamical mass due to the dominating relative uncertainty on the Hipparcos-Gaia proper motion anomaly that is used in the orbit-fitting routine. The publication of Gaia DR4 will likely ease this predicament. Based on the spectral analysis, we find that the companion is consistent with spectral type L8 and exhibits a potential metal enrichment in its atmosphere. Adopting the AMES-DUSTY model to infer its age, within its dynamical mass constraint the companion conceivably corresponds to either a younger (28-14+15 Myr) object with a mass just below the deuterium-burning limit or an older (119-10+37 Myr) body with a mass just above the deuterium-burning limit.Conclusions. These results do not yet allow for a definite inference of the companion's formation channel. Nevertheless, the new constraints on its bulk properties and the additional GRAVITY spectrum presented here will aid future efforts to determine the formation history of HIP 99770 b.
2025
Authors
Stolker, T; Samland, M; Waters, LBFM; van den Ancker, ME; Balmer, WO; Lacour, S; Sitko, ML; Wang, JJ; Nowak, M; Maire, AL; Kammerer, J; Otten, GPPL; Abuter, R; Amorim, A; Benisty, M; Berger, JP; Beust, H; Blunt, S; Boccaletti, A; Bonnefoy, M; Bonnet, H; Bordoni, MS; Bourdarot, G; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Chomez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Davies, R; Dembet, R; Dexter, J; Dominik, C; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Lopez, RG; Gardner, T; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Grant, S; Haubois, X; Heissel, G; Henning, T; Hinkley, S; Hippler, S; Houllé, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Kurtovic, NT; Lagrange, AM; Lapeyrère, V; Le Bouquin, JB; Lutz, D; Mang, F; Marleau, GD; Merand, A; Min, M; Mollière, P; Monnier, JD; Mordasini, C; Mouillet, D; Nasedkin, E; Ott, T; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Pfuhl, O; Pourré, N; Pueyo, L; Quanz, SP; Ribeiro, DC; Rickman, E; Rustamkulov, Z; Shangguan, J; Shimizu, T; Sing, D; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; van Dishoeck, EF; Vigan, A; Vincent, F; von Fellenberg, SD; Widmann, F; Winterhalder, TO; Woillez, J; Yazici, S;
Publication
ASTRONOMY & ASTROPHYSICS
Abstract
Context. HD135344AB is a young visual binary system that is best known for the protoplanetary disk around the secondary star. The circumstellar environment of the A0-type primary star, on the other hand, is already depleted. HD135344A is therefore an ideal target for the exploration of recently formed giant planets because it is not obscured by dust. Aims. We searched for and characterized substellar companions to HD135344A down to separations of about 10 au. Methods. We observed HD135344A with VLT/SPHERE in the H23 and K12 bands and obtained YJ and YJH spectroscopy. In addition, we carried out VLTI/GRAVITY observations for the further astrometric and spectroscopic confirmation of a detected companion. Results. We discovered a close-in young giant planet, HD135344Ab, with a mass of about 10 M-J. The multi-epoch astrometry confirms the bound nature based on common parallax and common proper motion. This firmly rules out the scenario of a non-stationary background star. The semi-major axis of the planetary orbit is approximately 15-20 au, and the photometry is consistent with that of a mid L-type object. The inferred atmospheric and bulk parameters further confirm the young and planetary nature of the companion. Conclusions. HD135344Ab is one of the youngest directly imaged planets that has fully formed and orbits on Solar System scales. It is a valuable target for studying the early evolution and atmosphere of a giant planet that could have formed in the vicinity of the snowline.
2025
Authors
Venkatesan, V; Blunt, S; Wang, JJ; Lacour, S; Marleau, GD; Coleman, GAL; Guerrero, L; Balmer, WO; Pueyo, L; Stolker, T; Kammerer, J; Pourré, N; Nowak, M; Rickman, E; Sivaramakrishnan, A; Sing, D; Wagner, K; Lagrange, AM; Abuter, R; Amorim, A; Asensio-Torres, R; Berger, JP; Beust, H; Boccaletti, A; Bonnefoy, M; Bonnet, H; Bordoni, MS; Bourdarot, G; Brandner, W; Cantalloube, F; Caselli, P; Charnay, B; Chauvin, G; Chavez, A; Chomez, A; Choquet, E; Christiaens, V; Clénet, Y; du Foresto, VC; Cridland, A; Davies, R; Dembet, R; Dexter, J; Drescher, A; Duvert, G; Eckart, A; Eisenhauer, F; Schreiber, NMF; Garcia, P; Lopez, RG; Gendron, E; Genzel, R; Gillessen, S; Girard, JH; Grant, S; Haubois, X; Heissel, G; Henning, T; Hinkley, S; Hippler, S; Houllé, M; Hubert, Z; Jocou, L; Keppler, M; Kervella, P; Kreidberg, L; Kurtovic, NT; Lapeyrère, V; Le Bouquin, JB; Lutz, D; Maire, AL; Mang, F; Mérand, A; Mordasini, C; Mouillet, D; Nasedkin, E; Ott, T; Otten, GPPL; Paladini, C; Paumard, T; Perraut, K; Perrin, G; Petrus, S; Pfuhl, O; Ribeiro, DC; Rustamkulov, Z; Shangguan, J; Shimizu, T; Shields, A; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; Tacconi, LJ; Vigan, A; Vincent, F; von Fellenberg, SD; Widmann, F; Winterhalder, TO; Woillez, J; Yazici, S;
Publication
ASTROPHYSICAL JOURNAL
Abstract
Understanding the orbits of giant planets is critical for testing planet formation models, particularly at wide separations (>10 au) where traditional core accretion becomes inefficient. However, constraining orbits at these separations has historically been challenging due to sparse orbital coverage and related degeneracies in the orbital parameters. In this work, we use existing high-resolution (R similar to 100,000) spectroscopic measurements from CRIRES+, astrometric data from SPHERE, NACO, and Atacama Large Millimeter/submillimeter Array, and combine it with new high-precision GRAVITY astrometry data to refine the orbit of GQ Lup B, a similar to 30 M-J companion at similar to 100 au, in a system that also hosts a circumstellar disk and a wide companion, GQ Lup C. Including radial velocity (RV) data significantly improves orbital constraints by breaking the degeneracy between inclination and eccentricity that plagues astrometry-only fits for long-period companions. Our work is one of the first to combine high-precision astrometry with the companion's relative radial velocity measurements to achieve significantly improved orbital constraints. The eccentricity is refined from e=0.47(-0.16)(+0.14 )(GRAVITY only) to e=0.35(-0.09)(+0.10) when RVs and GRAVITY data are combined. We also compute the mutual inclinations between the orbit of GQ Lup B, the circumstellar disk, the stellar spin axis, and the disk of GQ Lup C. The orbit is misaligned by 63(-14)(+6) degrees relative to the circumstellar disk, 52(-24)(+19 )degrees with the host star's spin axis, but appears more consistent ( 34-13+6 degrees) with the inclination of the wide tertiary companion GQ Lup C's disk. These results support a formation scenario for GQ Lup B consistent with cloud fragmentation. They highlight the power of combining companion RV constraints with interferometric astrometry to probe the dynamics and formation of wide-orbit substellar companions.
2024
Authors
Coelho, A; Ruela, J; Queirós, G; Trancoso, R; Correia, PF; Ribeiro, F; Fontes, H; Campos, R; Ricardo, M;
Publication
CoRR
Abstract
2024
Authors
Silva, SM; Almeida, NT;
Publication
2024 IEEE 22ND MEDITERRANEAN ELECTROTECHNICAL CONFERENCE, MELECON 2024
Abstract
The rapid proliferation of Internet of Things (IoT) systems, encompassing a wide range of devices and sensors with limited battery life, has highlighted the critical need for energy-efficient solutions to extend the operational lifespan of these battery-powered devices. One effective strategy for reducing energy consumption is minimizing the number and size of retransmitted packets in case of communication errors. Among the potential solutions, Incremental Redundancy Hybrid Automatic Repeat reQuest (IR-HARQ) communication schemes have emerged as particularly compelling options by adopting the best aspects of error control, namely, automatic repetition and variable redundancy. This work addresses the challenge by developing a simulator capable of executing and analysing several (H)ARQ schemes using different channel models, such as the Additive White Gaussian Noise (AWGN) and Gilbert-Elliott (GE) models. The primary objective is to compare their performance across multiple metrics, enabling a thorough evaluation of their capabilities. The results indicate that IR-HARQ outperforms alternative methods, especially in the presence of burst errors. Furthermore, its potential for further adaptation and enhancement opens up new ways for optimizing energy consumption and extending the lifespan of battery-powered IoT devices.
2024
Authors
Elsaid, M; Inacio, SI; Salgado, HM; Pessoa, LM;
Publication
2024 INTERNATIONAL CONFERENCE ON ELECTROMAGNETICS IN ADVANCED APPLICATIONS, ICEAA 2024
Abstract
The Sub-THz and millimeter-wave bands have gained popularity, with the expectation that they will host the next generation of wireless communication systems. Furthermore, research on beam-steering characteristics provided by Programmable Electromagnetic Surfaces, such as Reflective Intelligent Surfaces (RISs), has garnered considerable attention as an enabling technology for 6G communications. Due to size limitations, RISs face challenges related to power consumption in the reconfigurable elements and their integration with unit cells operating at high frequencies. This paper discusses the design of a 1-bit reconfigurable unit cell at the D-band using non-volatile technology to minimize static power consumption. Simulation results show that the proposed unit cell performs well with a reflection loss of less than 1.3 dB in both reconfigurable states across a frequency band from 120 to 170 GHz. Moreover, the phase difference between the two states is maintained at 180 degrees +/- 20 degrees, with an operational bandwidth of approximately 16 GHz. The beamforming capabilities, with steering angles from -60 degrees to 60 degrees, of the 12x12 RIS, utilizing the proposed unit cell, have been demonstrated in terms of controlling the main beam radiation precisely to various angles with consistent performance at frequencies of 147GHz,152GHz, and 152.5 GHz.
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