57 research outputs found
Characterisation of the hydrodynamic atmospheric escape of HD 209458 b, HD 189733 b, and GJ 3470 b
Interstellar matter and star formatio
Detection of He I \AA{} absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopy
We present three transit observations of HD 189733 b obtained with the
high-resolution spectrograph CARMENES at Calar Alto. A strong absorption signal
is detected in the near-infrared He I triplet at 10830 \AA{} in all three
transits. During mid-transit, the mean absorption level is %
measured in a 10 km s range at a net blueshift of km
s (10829.84--10830.57 \AA{}). The absorption signal exhibits radial
velocities of km s and km s during
ingress and egress, respectively; measured in the planetary rest frame. We show
that stellar activity related pseudo-signals interfere with the planetary
atmospheric absorption signal. They could contribute as much as 80% of the
observed signal and might also affect the radial velocity signature, but
pseudo-signals are very unlikely to explain the entire signal. The observed
line ratio between the two unresolved and the third line of the He I triplet is
, which strongly deviates from the value expected for an optically
thin atmospheres. When interpreted in terms of absorption in the planetary
atmosphere, this favors a compact helium atmosphere with an extent of only 0.2
planetary radii and a substantial column density on the order of cm. The observed radial velocities can be understood either in
terms of atmospheric circulation with equatorial superrotation or as a sign of
an asymmetric atmospheric component of evaporating material. We detect no clear
signature of ongoing evaporation, like pre- or post-transit absorption, which
could indicate material beyond the planetary Roche lobe, or radial velocities
in excess of the escape velocity. These findings do not contradict planetary
evaporation, but only show that the detected helium absorption in HD 189733 b
does not trace the atmospheric layers that show pronounced escape signatures.Comment: 13 pages, 12 figures, accepted for publication in A&
Ground-based detection of an extended helium atmosphere in the Saturn-mass exoplanet WASP-69b
Hot gas giant exoplanets can lose part of their atmosphere due to strong
stellar irradiation, affecting their physical and chemical evolution. Studies
of atmospheric escape from exoplanets have mostly relied on space-based
observations of the hydrogen Lyman-{\alpha} line in the far ultraviolet which
is strongly affected by interstellar absorption. Using ground-based
high-resolution spectroscopy we detect excess absorption in the helium triplet
at 1083 nm during the transit of the Saturn-mass exoplanet WASP-69b, at a
signal-to-noise ratio of 18. We measure line blue shifts of several km/s and
post transit absorption, which we interpret as the escape of part of the
atmosphere trailing behind the planet in comet-like form.
[Additional notes by authors: Furthermore, we provide upper limits for helium
signals in the atmospheres of the exoplanets HD 209458b, KELT-9b, and GJ 436b.
We investigate the host stars of all planets with detected helium signals and
those of the three planets we derive upper limits for. In each case we
calculate the X-ray and extreme ultraviolet flux received by these planets. We
find that helium is detected in the atmospheres of planets (orbiting the more
active stars and) receiving the larger amount of irradiation from their host
stars.]Comment: Submitted to Science on 14 March 2018; Accepted by Science on 16
November 2018; Published by Science on 6 December 2018. This is the author's
version of the work. It is posted here by permission of the AAAS for personal
use. The definitive version was published in Science, on 6 December 2018 -
Report: pages 21 (preprint), 4 figures - Supplementary materials: 22 pages,
10 figures, 3 table
On the study of atmospheric escape of exoplanets using the new window of the He 10830 line
Stars and planetary system
Characterisation of the upper atmospheres of HAT-P-32 b, WASP-69 b, GJ 1214 b, and WASP-76 b through their He I triplet absorption
Characterisation of atmospheres undergoing photo-evaporation is key to
understanding the formation, evolution, and diversity of planets. However, only
a few upper atmospheres that experience this kind of hydrodynamic escape have
been characterised. Our aim is to characterise the upper atmospheres of the hot
Jupiters HAT-P-32 b and WASP-69 b, the warm sub-Neptune GJ 1214 b, and the
ultra-hot Jupiter WASP-76 b through high-resolution observations of their HeI
triplet absorption. In addition, we also reanalyse the warm Neptune GJ 3470 b
and the hot Jupiter HD 189733 b. We used a spherically symmetric 1D
hydrodynamic model coupled with a non-local thermodynamic equilibrium model.
Comparing synthetic absorption spectra with observations, we constrained the
main parameters of the upper atmosphere of these planets and classify them
according to their hydrodynamic regime. Our results show that HAT-P-32 b
photo-evaporates at (13070)10 gs with a hot (12
4002900 K) upper atmosphere; WASP-69 b loses its atmosphere at
(0.90.5)10 gs and 5250750 K; and GJ 1214 b,
with a relatively cold outflow of 3750750 K, photo-evaporates at
(1.31.1)10 gs. For WASP-76 b, its weak absorption
prevents us from constraining its temperature and mass-loss rate significantly;
we obtained ranges of 6000-17 000\,K and 23.521.510
gs. Our reanalysis of GJ 3470 b yields colder temperatures, 3400350
K, but practically the same mass-loss rate as in our previous results. Our
reanalysis of HD 189733 b yields a slightly higher mass-loss rate,
(1.40.5)10 gs, and temperature, 12 700900 K
compared to previous estimates. Our results support that photo-evaporated
outflows tend to be very light
A Educación Global na Educación Secundaria Obligatoria: unha investigación diagnóstica nos centros educativos de Galicia
The collaborative research project "Exploring the possibilities of extending the global dimension of Education for Development in the ESO. Diagnostic investigation in the schools" is conducted between the GI "Education Policy, History and Society" of the UDC and Solidariedade International of Galician, funded by the Xunta de Galicia. The aim is to identify the needs of teachers and the school for mainstreaming Global Education in the curriculum. We started from the experience of UK, experts and Galician teachers to provide descriptions and resources for teachers to integrate this dimension in the classroom.O Proxecto de Investigación “Explorando as posibilidades de estender a dimensión global da educación para o desenvolvemento na ESO. Unha investigación diagnóstica en centros educativos” é unha proposta de investigación colaborativa entre o Grupo de Investigación Política Educativa, Historia e Sociedade da Universidade da Coruña e Solidariedade Internacional de Galicia, financiado pola Xunta de Galicia (PR804A 2014/07). O obxectivo é identificar as necesidades do profesorado e do centro educativo que colabora nos proxectos de Educación para o Desenvolvemento (EpD) de ONGDs para que estas accións sexan máis significativas para o alumnado. Tomamos como referencia a experiencia do Reino Unido. Trátase dunha investigación cualitativa para o quese aplicaron distintas estratexias de recollida de datos arredor de tres obxectivos: (i) saber como integraron no Reino Unido a dimensión global no curriculum e cales son as súas porpostas didácticas, (ii) coñecer outras experiencias , e (iii) desvelar cales son os intereses e necesidades do profesorado galego para integrar a dimensión global. Para abordar estos obxectivos utilizáronse técnicas que permitisen comprender as experiencias sociais nos escenarios naturais desde a perspectiva dos protagonistas, en concreto: 1. Análise de documentos para caracterizar a dimensión global no curriculo e nas propostas didácticas do Reino Unido, estructurando en unidades de significado as distintas fontes documentais a través de categorías. 2. Microestudos de caso en 6 centros educativos para coñecer os intereses e necesidades do profesorado individualmente e do centro no seu conxunto, mediante entrevistas –de corte narrativo e semiestructuradas– a tres tipos de informantes (membros do equipo directivo, responsables das bibliotecas e profesorado que xa desenvolve actividades de EpD nas aulas). 3. Os grupos focais para contrastar as distintas realidades dos centros educativos e contrastar posicionamentos de forma simultánea. 4. Entrevistas semiestructuradas a persoas expertas en Educación Global e 5. Elaboración de forma colaborativa dunha plataforma. Como estratexia xeral de análise aplicouse a codificación temática. A meta do estudo é proporcionar descripcións e interpretacións, e non xeralizacións, que permitan a outros docentes aplicar algunhas das conclusións e recomendacións a súa experiencia nas aulas. Con esta finalidade creouse unha plataforma dixital para facilitar o acceso a bibliografía, compartir experieincias e fomentar o intercambio
Water vapor detection in the transmission spectra of HD 209458 b with the CARMENES NIR channel
Aims: We aim at detecting HO in the atmosphere of the hot Jupiter HD
209458 b and perform a multi-band study in the near infrared with CARMENES.
Methods: The HO absorption lines from the planet's atmosphere are
Doppler-shifted due to the large change in its radial velocity during transit.
This shift is of the order of tens of km s, whilst the Earth's telluric
and the stellar lines can be considered quasi-static. We took advantage of this
to remove the telluric and stellar lines using SYSREM, a principal component
analysis algorithm. The residual spectra contain the signal from thousands of
planetary molecular lines well below the noise level. We retrieve this
information by cross-correlating the spectra with models of the atmospheric
absorption.
Results: We find evidence of HO in HD 209458 b with a signal-to-noise
ratio (S/N) of 6.4. The signal is blueshifted by --5.2 km
s, which, despite the error bars, is a firm indication of day-to-night
winds at the terminator of this hot Jupiter. Additionally, we performed a
multi-band study for the detection of HO individually from the three NIR
bands covered by CARMENES. We detect HO from its 1.0 m band with a S/N
of 5.8, and also find hints from the 1.15 m band, with a low S/N of 2.8.
No clear planetary signal is found from the 1.4 m band.
Conclusions: Our significant signal from the 1.0 m band in HD 209458 b
represents the first detection of HO from this band, the bluest one to
date. The unfavorable observational conditions might be the reason for the
inconclusive detection from the stronger 1.15 and 1.4 m bands. HO is
detected from the 1.0 m band in HD 209458 b, but hardly in HD 189733 b,
which supports a stronger aerosol extinction in the latter.Comment: 11 pages, 10 figures; accepted for publication in A&
Confirmation of an He I evaporating atmosphere around the 650-Myr-old sub-Neptune HD235088 b (TOI-1430 b) with CARMENES
HD235088 (TOI-1430) is a young star known to host a sub-Neptune-sized planet
candidate. We validated the planetary nature of HD235088 b with multiband
photometry, refined its planetary parameters, and obtained a new age estimate
of the host star, placing it at 600-800 Myr. Previous spectroscopic
observations of a single transit detected an excess absorption of He I
coincident in time with the planet candidate transit. Here, we confirm the
presence of He I in the atmosphere of HD235088 b with one transit observed with
CARMENES. We also detected hints of variability in the strength of the helium
signal, with an absorption of 0.910.11%, which is slightly deeper
(2) than the previous measurement. Furthermore, we simulated the He I
signal with a spherically symmetric 1D hydrodynamic model, finding that the
upper atmosphere of HD235088 b escapes hydrodynamically with a significant mass
loss rate of (1.5-5) 10g s, in a relatively cold outflow,
with =3125375 K, in the photon-limited escape regime. HD235088 b
( = 2.0450.075 R) is the smallest planet found to date
with a solid atmospheric detection - not just of He I but any other atom or
molecule. This positions it a benchmark planet for further analyses of evolving
young sub-Neptune atmospheres.Comment: Accepted for publication in A&A. 17 pages, 18 figure
Hα and He I absorption in HAT-P-32 b observed with CARMENES. Detection of Roche lobe overflow and mass loss
We analyze two high-resolution spectral transit time series of the hot Jupiter HAT-P-32 b obtained with the CARMENES spectrograph. Our new XMM-Newton X-ray observations of the system show that the fast-rotating F-type host star exhibits a high X-ray luminosity of 2.3 × 10 29 erg s -1 (5-100 Å), corresponding to a flux of 6.9 × 10 4 erg cm -2 s -1 at the planetary orbit, which results in an energy-limited escape estimate of about 10 13 g s -1 for the planetary mass-loss rate. The spectral time series show significant, time-dependent absorption in the Hα and Hea Iλ10833 triplet lines with maximum depths of about 3.3% and 5.3%. The mid-transit absorption signals in the Hα and Hea Iλ10833 lines are consistent with results from one-dimensional hydrodynamic modeling, which also yields mass-loss rates on the order of 10 13 g s -1. We observe an early ingress of a redshifted component of the transmission signal, which extends into a redshifted absorption component, persisting until about the middle of the optical transit. While a super-rotating wind can explain redshifted ingress absorption, we find that an up-orbit stream, transporting planetary mass in the direction of the star, also provides a plausible explanation for the pre-transit signal. This makes HAT-P-32 a benchmark system for exploring atmospheric dynamics via transmission spectroscopy. © ESO 2021.CARMENES is an instrument for the Centro Astronomico Hispano-Aleman (CAHA) at Calar Alto (Almeria, Spain), operated jointly by the Junta de Andalucia and the Instituto de Astrofisica de Andalucia (CSIC). CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Cientificas (CSIC), the Ministerio de Economia y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut fur Astronomie, Instituto de Astrofisica de Andalucia, Landessternwarte Konigstuhl, Institut de Ciencies de l'Espai, Institut fur Astrophysik Gottingen, Universidad Complutense de Madrid, Thuringer Landessternwarte Tautenburg, Instituto de Astrofisica de Canarias, Hamburger Sternwarte, Centro de Astrobiologia and Centro Astronomico Hispano-Aleman), with additional contributions by the MINECO, the Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme and Research Unit FOR2544 "Blue Planets around Red Stars", the Klaus Tschira Stiftung, the states of BadenWurttemberg and Niedersachsen, and by the Junta de Andalucia. Based on data from the CARMENES data archive at CAB (CSIC-INTA). We acknowledge financial support from the Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades and the ERDF through projects PID2019-109522GB-C5[1:4]/AEI/10.13039/501100011033 PGC2018-098153-B-C33 and the Centre of Excellence "Severo Ochoa" and "Maria de Maeztu" awards to the Instituto de Astrofisica de Canarias (SEV-2015-0548), Instituto de Astrofisica de Andalucia (SEV-2017-0709), and Centro de Astrobiologia (MDM-2017-0737), the Generalitat de Catalunya/CERCA programme. D. Yan acknowledges support by the Strategic Priority Research Program of Chinese Academy of Sciences, Grant No. XDB 41000000 and National Natural Science Foundation of China (Nos. 11973082). SC and EN acknowledge DFG support under grants CZ 222/3-1 and CZ 222/5-1. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.Peer reviewe
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