We present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the ∼150 kpc Lyα halo around the z = 4.1 radio galaxy TN J1338−1942. This 9-h observation maps ...the full two-dimensional kinematics of the Lyα emission across the halo, which shows a velocity gradient of Δv ∼ 700 km s−1 across 150 kpc in projection, and also identified two absorption systems associated with the Lyα emission from the radio galaxy. Both absorbers have high covering fractions (∼1) spanning the full ∼150 × 80 kpc2 extent of the halo. The stronger and more blueshifted absorber (Δv ∼ −1200 km s−1 from the systemic) has dynamics that mirror that of the underlying halo emission and we suggest that this high column material (n(H i) ∼ 1019.4 cm−2), which is also seen in C iv absorption, represents an outflowing shell that has been driven by the active galactic nuclei (AGN) or the star formation within the galaxy. The weaker (n(H i) ∼ 1014 cm−2) and less blueshifted (Δv ∼ −500 km s−1) absorber most likely represents material in the cavity between the outflowing shell and the Lyα halo. We estimate that the mass in the shell must be ∼1010 M⊙ – a significant fraction of the interstellar medium from a galaxy at z = 4. The large scales of these coherent structures illustrate the potentially powerful influence of AGN feedback on the distribution and energetics of material in their surroundings. Indeed, the discovery of high-velocity (∼1000 km s−1), group-halo-scale (i.e. >150 kpc) and mass-loaded winds in the vicinity of the central radio source is in agreement with the requirements of models that invoke AGN-driven outflows to regulate star formation and black hole growth in massive galaxies.
ABSTRACT Asteroid (3200) Phaethon is a Near-Earth Apollo asteroid with an unusual orbit that brings it closer to the Sun than any other known asteroid. Its last close approach to the Earth was in ...2017 mid-December and the next one will be on 2026 October. Previous rotationally time-resolved spectroscopy of Phaethon showed that its spectral slope is slightly bluish, in agreement with its B/F taxonomic classification, but at some rotational phases, it changes to slightly reddish. Motivated by this result, we performed time-resolved imaging polarimetry of Phaethon during its recent close approach to the Earth. Phaethon has a spin period of 3.604 h, and we found a variation of the linear polarization with rotation. This seems to be a rare case in which such variation is unambiguously found, also a consequence of its fairly large amplitude. Combining this new information with the brightness and colour variation as well as previously reported results from Arecibo radar observations, we conclude that there is no variation of the mineralogy across the surface of Phaeton. However, the observed change in the linear polarization may be related to differences in the thickness of the surface regolith in different areas or local topographic features.
ABSTRACT
We present intensity interferometry of the luminous blue variable P Cyg in the light of its H α emission performed with 1 m-class telescopes. We compare the measured visibility points to ...synthesized interferometric data based on the CMFGEN physical modelling of a high-resolution spectrum of P Cyg recorded almost simultaneously with our interferometry data. Tuning the stellar parameters of P Cyg and its H α linear diameter, we estimate the distance of P Cyg as 1.56 ± 0.25 kpc, which is compatible within 1σ with 1.36 ± 0.24 kpc reported by the Gaia DR2 catalogue of parallaxes recently published. Both the values are significantly smaller than the canonic value of 1.80 ± 0.10 kpc usually adopted in literature. Our method used to calibrate the distance of P Cyg can apply to very massive and luminous stars both in our Galaxy and neighbouring galaxies, and can improve the so-called wind momentum–luminosity relation that potentially applies to calibrate cosmological candles in the local Universe.
Abstract
We report the first intensity correlation measured with starlight since the historical experiments of Hanbury Brown and Twiss. The photon bunching g(2)(τ, r = 0), obtained in the ...photon-counting regime, was measured for three bright stars: α Boo, α CMi and β Gem. The light was collected at the focal plane of a 1-m optical telescope, transported by a multi-mode optical fibre, split into two avalanche photodiodes and correlated digitally in real time. For total exposure times of a few hours, we obtained contrast values around 2 × 10−3, in agreement with the expectation for chaotic sources, given the optical and electronic bandwidths of our set-up. Comparing our results with the measurement of Hanbury Brown et al. for α CMi, we argue for the timely opportunity to extend our experiments to measuring the spatial correlation function over existing and/or foreseen arrays of optical telescopes diluted over several kilometres. This would enable microarcsec long-baseline interferometry in the optical, especially in the visible wavelengths, with a limiting magnitude of 10.
ABSTRACT
In this paper, we report on spatial intensity interferometry measurements within the Hα line on two stars: the Luminous Blue Variable supergiant P Cygni and the late-type B supergiant ...Rigel. The experimental setup was upgraded to allow simultaneous measurement of two polarization channels, instead of one in our previous setup, and the zero baseline correlation function on-sky to validate independent estimates obtained from the stellar spectrum and the instrumental spectral throughput. Combined with simultaneous spectra measurements and based on radiative transfer models calculated with the code CMFGEN, we were able to fit our measured visibility curves to extract the stellar distances. Our distance determinations for both P Cygni (1.61 ± 0.18 kpc) and Rigel (0.26 ± 0.02 kpc) agree very well with the values provided by astrometry with the Gaia and Hipparcos missions, respectively. This result for Rigel was obtained by adopting a stellar luminosity of L⋆ = 123 000 L⊙, which is reported in the literature as being consistent with the Hipparcos distance to Rigel. However, due to the lack of consensus on Rigel’s luminosity, we also explore how the adoption of the stellar luminosity in our models affects our distance determination for Rigel. In conclusion, we support, in an independent way, the distance to Rigel as the one provided by the Hipparcos mission, when taking the luminosity of 123 000 L⊙ at face value. This study is the first successful step towards extending the application of the Wind Momentum Luminosity Relation method for distance calibration from an LBV supergiant to a more normal late-type B supergiant.
ABSTRACT
We present new speckle measurements of the position of Linus, the satellite of the asteroid (22) Kalliope, obtained at the 1 m Centre Pédagogique Planètes et Univers-Epsilon telescope on the ...Plateau de Calern, France. Observations were made in the visible domain with the speckle camera Pupil Interferometry Speckle camera and COronagraph. We obtained 122 measurements in February–March 2022 and April 2023, with a mean uncertainty close to 10 milliarcsec on the angular separation.
Context.
Since July 2014, the
Gaia
mission of the European Space Agency has been surveying the entire sky down to magnitude 20.7 in the visible. In addition to the millions of daily observations of ...stars, thousands of Solar System objects (SSOs) are observed. By comparing their positions, as measured by
Gaia
, to those of known objects, a daily processing pipeline filters known objects from potential discoveries. However, owing to
Gaia
’s specific observing mode, which follows a predetermined scanning law designed for stars as “fixed” objects on the celestial sphere, potential newly discovered moving objects are characterized by very few observations, which are acquired over a limited time. Furthermore, these objects cannot be specifically targeted by
Gaia
itself after their first detection. This aspect was recognized early on in the design of the
Gaia
data processing.
Aims.
A daily processing pipeline dedicated to these candidate discoveries was set up to release calls for observations to a network of ground-based telescopes. Their aim is to acquire follow-up astrometry and to characterize these objects.
Methods.
From the astrometry measured by
Gaia
, preliminary orbital solutions are determined, allowing us to predict the position of these potentially newly discovered objects in the sky while accounting for the large parallax between
Gaia
and the Earth (separated by 0.01 au). A specific task within the
Gaia
Data Processing and Analysis Consortium has been responsible for the distribution of requests for follow-up observations of potential
Gaia
SSO discoveries. Since late 2016, these calls for observations (nicknamed “alerts”) have been published via a Web interface with a quasi-daily frequency, together with observing guides, which is freely available to anyone worldwide.
Results.
Between November 2016 and the end of the first year of the extended mission (July 2020), over 1700 alerts were published, leading to the successful recovery of more than 200 objects. Among them, six have a provisional designation assigned with the
Gaia
observations; the others were previously known objects with poorly characterized orbits, precluding identification at the time of
Gaia
observations. There is a clear trend for objects with a high inclination to be unidentified, revealing a clear bias in the current census of SSOs against high-inclination populations.
Aging-related erectile dysfunction is characterized by a loss of smooth muscle cells (SMCs) and fibrosis in the corpora cavernosa,
and functionally by corporal veno-occlusive dysfunction (CVOD). ...Phosphodiesterase 5 (PDE5A) inhibitors, in part via upregulating
inducible nitric oxide synthase (NOS2A), have antifibrotic properties in penile tissues. We aimed to determine whether in
the aged rat the chronic long-term treatment with sildenafil ameliorates corporal SMC loss and fibrosis, stimulates NOS2A
induction, and corrects the associated CVOD. Aged male rats (20 mo old) received sildenafil in their drinking water (20 mg/kg
per day) or plain water for 45 days, and untreated young rats (5 mo old) served as controls (n = 8 per group). CVOD was assessed
by dynamic infusion cavernosometry (DIC). Collagen:SMC (Masson trichrome) and collagen III:I (picrosirius red) ratios, SMC
content (alpha-smooth muscle actin ACTA2), cell proliferation (proliferating nuclear antigen PCNA), apoptotic death (TUNEL),
and NOS2A induction were measured by histochemistry and immunohistochemistry followed by quantitative image analysis. Collagen
content was determined by hydroxyproline assay, and transforming growth factor beta-1 (TGFB1); xanthine oxidoreductase (XDH);
ACTA2; NOS2A; and the Rho kinase inhibitor protein tyrosine phosphatase, nonreceptor type 11 (PTPN11), and activator, VAV,
were measured by quantitative Western blot. In the aged rats treated with sildenafil, the erectile response by DIC was normalized,
and the corporal SMC:collagen ratio and SMC number were increased. In addition, sildenafil reduced the corporal collagen content
without affecting the collagen III:I ratio, increased the PCNA:apoptosis ratio, and stimulated NOS2A induction, although there
was no effect on XDH, TGFB1, PTPN11, or VAV levels. These data show that long-term PDE5A treatment corrected CVOD in the aged
rat and partially reversed the aging-related fibrosis and loss of SMC in the corpora cavernosa without affecting TGFB1 or
PTPN11 levels, which are markers of oxidative stress. It may be speculated that similar effects may be achieved with this
paradigm in men.
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