27 research outputs found
Light pollution at the Roque de los Muchachos Observatory
Sky spectra were obtained from archival science frames taken with DoLoRes at
the 3.58m Telescopio Nazionale Galileo with a wavelength range ~3800 - 8000Ang
and resolution of 2.8Ang/pix and 3.6Ang/pix. Our spectra include all the
important Sodium and Mercury light pollution lines and span a wide interval of
azimuth and observing conditions, essential to disentangle environmental and
seasonal effects. New sodium and mercury lines were also detected for the first
time at the observatory. Light pollution from NaD_{5892-8} emitted by the LPS
lamps increased by a factor of 1.5 - 2 with respect to the average values of
1998. At the same time, light pollution from Hg lines decreased by ~40% and
reaches the 1998 levels only when observing toward the towns. The contribution
of NaD_{5892-8} from LPS lamps to sky background is 0.05-0.10mag at V-band and
0.07-0.12mag at R-band. Synthetic sky brightness measures calculated from our
spectra at V, B and R bands are in good agreement with those of Benn &
Ellison(1998) if we take into account that our observations were done during
2003, seven years after the last sunspot minimum. The effects of the
application of the Canary Sky Law are directly visible in the spectra as a 50%
dimming of the Hg light-polluting lines in the spectra taken after local
midnight.Comment: 13 pages, 2 figures; Accepted for publication in New Astronom
Investigating the radio-loud phase of broad absorption line quasars
Context. Broad absorption lines (BALs) are present in the spectra of ~20% of quasars (QSOs); this indicates fast outflows (up to 0.2c) that intercept the observerâs line of sight. These QSOs can be distinguished again into radio-loud (RL) BAL QSOs and radio-quiet (RQ) BAL QSOs. The first are very rare, even four times less common than RQ BAL QSOs. The reason for this is still unclear and leaves open questions about the nature of the BAL-producing outflows and their connection with the radio jet.
Aims. We explored the spectroscopic characteristics of RL and RQ BAL QSOs with the aim to find a possible explanation for the rarity of RL BAL QSOs.
Methods. We identified two samples of genuine BAL QSOs from SDSS optical spectra, one RL and one RQ, in a suitable redshift interval (2.5 < z < 3.5) that allowed us to observe the Mg?ii and HĂ emission lines in the adjacent near-infrared (NIR) band. We collected NIR spectra of the two samples using the Telescopio Nazionale Galileo (TNG, Canary Islands). By using relations known in the literature, we estimated the black-hole mass, the broad-line region radius, and the Eddington ratio of our objects and compared the two samples.
Results. We found no statistically significant differences from comparing the distributions of the cited physical quantities. This indicates that they have similar geometries, accretion rates, and central black-hole masses, regardless of whether the radio-emitting jet is present or not.
Conclusions. These results show that the central engine of BAL QSOs has the same physical properties with and without a radio jet. The reasons for the rarity of RL BAL QSOs must reside in different environmental or evolutionary variables.Acknowledgements. The authors acknowledge financial support from the Spanish Ministerio de Ciencia e InnovaciĂłn under projects AYA2008-06311-C02-02 and AYA2011-29517-C03-02. Part of this work was supported by the COST Action MP0905 âBlack Holes in a Violent Universeâ. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) oper-ated on the island of La Palma by the FundaciĂłn Galileo Galilei of the INAF
Characterizing K2 planet discoveries : a super-Earth transiting the bright K dwarf HIP 116454
We report the first planet discovery from the two-wheeled Kepler (K2) mission: HIP 116454 b. The host star HIP 116454 is a bright (V = 10.1, K = 8.0) K1 dwarf with high proper motion and a parallax-based distance of 55.2 ± 5.4 pc. Based on high-resolution optical spectroscopy, we find that the host star is metal-poor with [Fe/H] =â0.16 ± 0.08 and has a radius R = 0.716 ± 0.024 R â and mass M = 0.775 ± 0.027 M â. The star was observed by the Kepler spacecraft during its Two-Wheeled Concept Engineering Test in 2014 February. During the 9 days of observations, K2 observed a single transit event. Using a new K2 photometric analysis technique, we are able to correct small telescope drifts and recover the observed transit at high confidence, corresponding to a planetary radius of pR = 2.53 ± 0.18 R â. Radial velocity observations with the HARPS-N spectrograph reveal a 11.82 ± 1.33 M â planet in a 9.1 day orbit, consistent with the transit depth, duration, and ephemeris. Follow-up photometric measurements from the MOST satellite confirm the transit observed in the K2 photometry and provide a refined ephemeris, making HIP 116454 b amenable for future follow-up observations of this latest addition to the growing population of transiting super-Earths around nearby, bright stars.Publisher PDFPeer reviewe
Five carbon- and nitrogen-bearing species in a hot giant planet's atmosphere
The atmospheres of gaseous giant exoplanets orbiting close to their parent
stars (hot Jupiters) have been probed for nearly two decades. They allow us to
investigate the chemical and physical properties of planetary atmospheres under
extreme irradiation conditions. Previous observations of hot Jupiters as they
transit in front of their host stars have revealed the frequent presence of
water vapour and carbon monoxide in their atmospheres; this has been studied in
terms of scaled solar composition under the usual assumption of chemical
equilibrium. Both molecules as well as hydrogen cyanide were found in the
atmosphere of HD 209458b, a well studied hot Jupiter (with equilibrium
temperature around 1,500 kelvin), whereas ammonia was tentatively detected
there and subsequently refuted. Here we report observations of HD 209458b that
indicate the presence of water (H2O), carbon monoxide (CO), hydrogen cyanide
(HCN), methane (CH4), ammonia (NH3) and acetylene (C2H2), with statistical
significance of 5.3 to 9.9 standard deviations per molecule. Atmospheric models
in radiative and chemical equilibrium that account for the detected species
indicate a carbon-rich chemistry with a carbon-to-oxygen ratio close to or
greater than 1, higher than the solar value (0.55). According to existing
models relating the atmospheric chemistry to planet formation and migration
scenarios, this would suggest that HD 209458b formed far from its present
location and subsequently migrated inwards. Other hot Jupiters may also show a
richer chemistry than has been previously found, which would bring into
question the frequently made assumption that they have solar-like and
oxygen-rich compositions.Comment: As part of the Springer Nature Content Sharing Initiative, it is
possible to access a view-only version of this paper by using the following
SharedIt link: https://rdcu.be/cifr
The TESS-Keck Survey. XII. A Dense 1.8 R â Ultra-short-period Planet Possibly Clinging to a High-mean-molecular-weight Atmosphere after the First Gigayear
The extreme environments of ultra-short-period planets (USPs) make excellent laboratories to study how exoplanets obtain, lose, retain, and/or regain gaseous atmospheres. We present the confirmation and characterization of the USP TOI-1347 b, a 1.8±0.1 Râ planet on a 0.85 day orbit that was detected with photometry from the TESS mission. We measured radial velocities of the TOI-1347 system using Keck/HIRES and HARPS-N and found the USP to be unusually massive at 11.1±1.2 Mâ. The measured mass and radius of TOI-1347 b imply an Earth-like bulk composition. A thin H/He envelope (>0.01% by mass) can be ruled out at high confidence. The system is between 1 and 1.8 Gyr old; therefore, intensive photoevaporation should have concluded. We detected a tentative phase curve variation (3Ï) and a secondary eclipse (2Ï) in TESS photometry, which if confirmed could indicate the presence of a high-mean-molecular-weight atmosphere. We recommend additional optical and infrared observations to confirm the presence of an atmosphere and investigate its composition
The GAPS Programme at TNG XXXIX. Multiple molecular species in the atmosphere of the warm Giant Planet WASP-80 b unveiled at high resolution with GIANO-B*
Detections of molecules in the atmosphere of gas giant exoplanets allow us to investigate the physico-chemical properties of the atmospheres. Their inferred chemical composition is used as tracer of planet formation and evolution mechanisms. Currently, an increasing number of detections is showing a possible rich chemistry of the hotter gaseous planets, but whether this extends to cooler giants is still unknown. We observed four transits of WASP-80 b, a warm transiting giant planet orbiting a late-K dwarf star with the near-infrared GIANO-B spectrograph installed at the Telescopio Nazionale Galileo and performed high-resolution transmission spectroscopy analysis. We report the detection of several molecular species in its atmosphere. Combining the four nights and comparing our transmission spectrum to planetary atmosphere models containing the signature of individual molecules within the cross-correlation framework, we find the presence of H2O, CH4, NH3, and HCN with high significance, tentative detection of CO2, and inconclusive results for C2H2 and CO. A qualitative interpretation of these results, using physically motivated models, suggests an atmosphere consistent with solar composition and the presence of disequilibrium chemistry and we therefore recommend the inclusion of the latter in future modeling of sub-1000 K planets
Precise Masses in the WASP-47 System
We present precise radial velocity observations of WASP-47, a star known to
host a hot Jupiter, a distant Jovian companion, and, uniquely, two additional
transiting planets in short-period orbits: a super-Earth in a ~19 hour orbit,
and a Neptune in a ~9 day orbit. We analyze our observations from the HARPS-N
spectrograph along with previously published data to measure the most precise
planet masses yet for this system. When combined with new stellar parameters
and reanalyzed transit photometry, our mass measurements place strong
constraints on the compositions of the two small planets. We find unlike most
other ultra-short-period planets, the inner planet, WASP-47 e, has a mass (6.83
+/- 0.66 Me) and radius (1.810 +/- 0.027 Re) inconsistent with an Earth-like
composition. Instead, WASP-47 e likely has a volatile-rich envelope surrounding
an Earth-like core and mantle. We also perform a dynamical analysis to
constrain the orbital inclination of WASP-47 c, the outer Jovian planet. This
planet likely orbits close to the plane of the inner three planets, suggesting
a quiet dynamical history for the system. Our dynamical constraints also imply
that WASP-47 c is much more likely to transit than a geometric calculation
would suggest. We calculate a transit probability for WASP-47 c of about 10%,
more than an order of magnitude larger than the geometric transit probability
of 0.6%.Comment: 15 pages, 3 figures, 3 tables. Accepted in A
K2-79b and K2-222b: Mass Measurements of Two Small Exoplanets with Periods beyond 10 days that Overlap with Periodic Magnetic Activity Signals
Abstract
We present mass and radius measurements of K2-79b and K2-222b, two transiting exoplanets orbiting active G-type stars observed with HARPS-N and K2. Their respective 10.99 day and 15.39 day orbital periods fall near periods of signals induced by stellar magnetic activity. The two signals might therefore interfere and lead to an inaccurate estimate of exoplanet mass. We present a method to mitigate these effects when radial velocity (RV) and activity-indicator observations are available over multiple observing seasons and the orbital period of the exoplanet is known. We perform correlation and periodogram analyses on subsets composed of each target's two observing seasons, in addition to the full data sets. For both targets, these analyses reveal an optimal season with little to no interference at the orbital period of the known exoplanet. We make a confident mass detection of each exoplanet by confirming agreement between fits to the full RV set and the optimal season. For K2-79b, we measure a mass of 11.8 ± 3.6 M
â and a radius of 4.09 ± 0.17 R
â. For K2-222b, we measure a mass of 8.0 ± 1.8 M
â and a radius of 2.35 ± 0.08 R
â. According to model predictions, K2-79b is a highly irradiated Uranus analog and K2-222b hosts significant amounts of water ice. We also present a RV solution for a candidate second companion orbiting K2-222 at 147.5 days.</jats:p