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  • 1
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 670 ( 2023-2), p. A139-
    Abstract: Context. The CARMENES instrument, installed at the 3.5 m telescope of the Calar Alto Observatory in Almería, Spain, was conceived to deliver high-accuracy radial velocity (RV) measurements with long-term stability to search for temperate rocky planets around a sample of nearby cool stars. Moreover, the broad wavelength coverage was designed to provide a range of stellar activity indicators to assess the nature of potential RV signals and to provide valuable spectral information to help characterise the stellar targets. Aims. We describe the CARMENES guaranteed time observations (GTO), spanning from 2016 to 2020, during which 19 633 spectra for a sample of 362 targets were collected. We present the CARMENES Data Release 1 (DR1), which makes public all observations obtained during the GTO of the CARMENES survey. Methods. The CARMENES survey target selection was aimed at minimising biases, and about 70% of all known M dwarfs within 10 pc and accessible from Calar Alto were included. The data were pipeline-processed, and high-level data products, including 18 642 precise RVs for 345 targets, were derived. Time series data of spectroscopic activity indicators were also obtained. Results. We discuss the characteristics of the CARMENES data, the statistical properties of the stellar sample, and the spectroscopic measurements. We show examples of the use of CARMENES data and provide a contextual view of the exoplanet population revealed by the survey, including 33 new planets, 17 re-analysed planets, and 26 confirmed planets from transiting candidate follow-up. A subsample of 238 targets was used to derive updated planet occurrence rates, yielding an overall average of 1.44 ± 0.20 planets with 1 M ⊕ 〈 M pl sin i 〈 1000 M ⊕ and 1 day 〈 P orb 〈 1000 days per star, and indicating that nearly every M dwarf hosts at least one planet. All the DR1 raw data, pipeline-processed data, and high-level data products are publicly available online. Conclusions. CARMENES data have proven very useful for identifying and measuring planetary companions. They are also suitable for a variety of additional applications, such as the determination of stellar fundamental and atmospheric properties, the characterisation of stellar activity, and the study of exoplanet atmospheres.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2023
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 2
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 612 ( 2018-4), p. A49-
    Abstract: The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R 〉 80 000, and we measure its RV, H α emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q , and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s −1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s −1 .
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 3
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 609 ( 2018-1), p. L5-
    Abstract: We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 ( V  = 8.9 mag, M  = 0.58 ± 0.08  M ⊙ ), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of K  = 5.1 ± 0.4 m s −1 and a period of P  = 86.54 ± 0.06 d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass m P  sin  i  = 25 ± 2  M ⊕ , 1.5 times the mass of Neptune, with an orbital semi-major axis a  = 0.32 au and low eccentricity ( e 〈 0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1 d (and its first harmonic), which we attribute to the rotation period of the star.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 4
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 664 ( 2022-8), p. A199-
    Abstract: We report the discovery of a multiplanetary system transiting the M0 V dwarf HD 260655 (GJ 239, TOI-4599). The system consists of at least two transiting planets, namely HD 260655 b, with a period of 2.77 d, a radius of R b = 1.240 ± 0.023 R ⊕ , a mass of M b = 2.14 ± 0.34 M ⊕ , and a bulk density of ρ b = 6.2 ± 1.0 g cm −3 , and HD 260655 c, with a period of 5.71 d, a radius of ${R_c} = 1.533_{ - 0.046}^{ + 0.051}{R_ \oplus }$, a mass of M c = 3.09 ± 0.48 M ⊕ , and a bulk density of ${\rho _c} = 4.7_{ - 0.8}^{ + 0.9}{\rm{g}}$ g cm −3 . The planets have been detected in transit by the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed independently with archival and new precise radial velocities obtained with the HIRES and CARMENES instruments since 1998 and 2016, respectively. At a distance of 10 pc, HD 260655 has become the fourth closest known multitransiting planet system after HD 219134, LTT 1445 A, and AU Mic. Due to the apparent brightness of the host star ( J = 6.7 mag), both planets are among the most suitable rocky worlds known today for atmospheric studies with the James Webb Space Telescope, both in transmission and emission.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2022
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 5
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 628 ( 2019-8), p. A39-
    Abstract: We report the detection of a transiting Earth-size planet around GJ 357, a nearby M2.5 V star, using data from the Transiting Exoplanet Survey Satellite (TESS). GJ 357 b (TOI-562.01) is a transiting, hot, Earth-sized planet ( T eq = 525 ± 11 K) with a radius of R b = 1.217 ± 0.084 R ⊕ and an orbital period of P b = 3.93 d. Precise stellar radial velocities from CARMENES and PFS, as well as archival data from HIRES, UVES, and HARPS also display a 3.93-day periodicity, confirming the planetary nature and leading to a planetary mass of M b = 1.84 ± 0.31 M ⊕ . In addition to the radial velocity signal for GJ 357 b, more periodicities are present in the data indicating the presence of two further planets in the system: GJ 357 c, with a minimum mass of M c = 3.40 ± 0.46 M ⊕ in a 9.12 d orbit, and GJ 357 d, with a minimum mass of M d = 6.1 ± 1.0 M ⊕ in a 55.7 d orbit inside the habitable zone. The host is relatively inactive and exhibits a photometric rotation period of P rot = 78 ± 2 d. GJ 357 b isto date the second closest transiting planet to the Sun, making it a prime target for further investigations such as transmission spectroscopy. Therefore, GJ 357 b represents one of the best terrestrial planets suitable for atmospheric characterization with the upcoming JWST and ground-based ELTs.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 6
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 639 ( 2020-7), p. A132-
    Abstract: We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384–1735–1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than that of Earth. In particular, we measure a mass of M p = 5.9 ± 0.6 M ⊕ and a radius of R p = 1.69 ± 0.08 R ⊕ , which together result in a density of ρ p = 6.7 − 1.1 + 1.3 g cm −3 . When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass places our discovery in the radius gap, which is a transition region between rocky planets and planets with significant atmospheric envelopes. A few examples of planets occupying the radius gap are known to date. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R ⊕ or larger at the insolation levels received by TOI-1235 b (~60 S ⊕ ). This makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 7
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 627 ( 2019-7), p. A49-
    Abstract: Context. Teegarden’s Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden’s Star and analysed them for planetary signals. Methods. We find periodic variability in the radial velocities of Teegarden’s Star. We also studied photometric measurements to rule out stellar brightness variations mimicking planetary signals. Results. We find evidence for two planet candidates, each with 1.1 M ⊕ minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age. Conclusions. The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 8
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 609 ( 2018-1), p. A117-
    Abstract: Context. The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary companion (GJ 15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary systems (GJ 581 and GJ 876). Aims. We aim to report new precise optical radial velocity measurements for these planet hosts and test the overall capabilities of CARMENES. Methods. We combined our CARMENES precise Doppler measurements with those available from HIRES and HARPS and derived new orbital parameters for the systems. Bona-fide single planet systems were fitted with a Keplerian model. The multiple planet systems were analyzed using a self-consistent dynamical model and their best fit orbits were tested for long-term stability. Results. We confirm or provide supportive arguments for planets around all the investigated stars except for GJ 15 A, for which we find that the post-discovery HIRES data and our CARMENES data do not show a signal at 11.4 days. Although we cannot confirm the super-Earth planet GJ 15 Ab, we show evidence for a possible long-period ( P c = 7030 -630 +970 d) Saturn-mass ( m c sin i = 51.8 -5.8 +5.5 M ⊕ ) planet around GJ 15 A. In addition, based on our CARMENES and HIRES data we discover a second planet around GJ 1148, for which we estimate a period P c = 532.6 -2.5 +4.1 days, eccentricity e c = 0.342 -0.062 +0.050 and minimum mass m c sin i = 68.1 -2.2 +4.9 M ⊕ . Conclusions. The CARMENES optical radial velocities have similar precision and overall scatter when compared to the Doppler measurements conducted with HARPS and HIRES. We conclude that CARMENES is an instrument that is up to the challenge of discovering rocky planets around low-mass stars.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 9
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 642 ( 2020-10), p. A236-
    Abstract: We present the confirmation and characterisation of GJ 3473 b (G 50–16, TOI-488.01), a hot Earth-sized planet orbiting an M4 dwarf star, whose transiting signal ( P = 1.1980035 ± 0.0000018 d) was first detected by the Transiting Exoplanet Survey Satellite (TESS). Through a joint modelling of follow-up radial velocity observations with CARMENES, IRD, and HARPS together with extensive ground-based photometric follow-up observations with LCOGT, MuSCAT, and MuSCAT2, we determined a precise planetary mass, M b = 1.86 ± 0.30 M ⊕ , and radius, R b = 1.264 ± 0.050 R ⊕ . Additionally, we report the discovery of a second, temperate, non-transiting planet in the system, GJ 3473 c, which has a minimum mass, M c sin i = 7.41 ± 0.91 M ⊕ , and orbital period, P c = 15.509 ± 0.033 d. The inner planet of the system, GJ 3473 b, is one of the hottest transiting Earth-sized planets known thus far, accompanied by a dynamical mass measurement, which makes it a particularly attractive target for thermal emission spectroscopy.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
    Location Call Number Limitation Availability
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  • 10
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 658 ( 2022-2), p. A138-
    Abstract: Context. The number of super-Earth and Earth-mass planet discoveries has increased significantly in the last two decades thanks to the Doppler radial velocity and planetary transit observing techniques. Either technique can detect planet candidates on its own, but the power of a combined photometric and spectroscopic analysis is unique for an insightful characterization of the planets, which in turn has repercussions for our understanding of the architecture of planetary systems and, therefore, their formation and evolution. Aims. Two transiting planet candidates with super-Earth radii around the nearby ( d = 70.64 ± 0.06 pc) K7–M0 dwarf star TOI-1238 were announced by NASA’s Transiting Exoplanet Survey Satellite (TESS), which observed the field of TOI-1238 in four different sectors. We aim to validate their planetary nature using precise radial velocities taken with the CARMENES spectrograph. Methods. We obtained 55 CARMENES radial velocity measurements that span the 11 months between 9 May 2020 and 5 April 2021. For a better characterization of the parent star’s activity, we also collected contemporaneous optical photometric observations at the Joan Oró and Sierra Nevada observatories and retrieved archival photometry from the literature. We performed a combined TESS+CARMENES photometric and spectroscopic analysis by including Gaussian processes and Keplerian orbits to account for the stellar activity and planetary signals simultaneously. Results. We estimate that TOI-1238 has a rotation period of 40 ± 5 d based on photometric and spectroscopic data. The combined analysis confirms the discovery of two transiting planets, TOI-1238 b and c, with orbital periods of 0.764597 −0.000011 +0.000013 d and 3.294736 −0.000036 +0.000034 d, masses of 3.76 −1.07 +1.15 M ⊕ and 8.32 −1.88 +1.90 M ⊕ , and radii of 1.21 −0.10 +0.11 R ⊕ and 2.11 −0.14 +0.14 R ⊕ . They orbit their parent star at semimajor axes of 0.0137 ± 0.0004 au and 0.036 ± 0.001 au, respectively.The two planets are placed on opposite sides of the radius valley for M dwarfs and lie between the star and the inner border of TOI-1238’s habitable zone. The inner super-Earth TOI-1238 b is one of the densest ultra-short-period planets ever discovered ( ρ = 11.7 −3.4 +4.2 g cm −3 ). The CARMENES data also reveal the presence of an outer, non-transiting, more massive companion with an orbital period and radial velocity amplitude of ≥600 d and ≥70 m s −1 , which implies a likely mass of M ≥ 2 √(1− e 2 ) M Jup and a separation ≥1.1 au from its parent star.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    RVK:
    RVK:
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2022
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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