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Kinetic Alfvén Waves in Space Plasma Environment with κ-electrons

Lakhina, G. S.; Singh, S. V.; Barik, K. C.

A resonant instability of kinetic Alfvén waves (KAWs) driven by ion beam is discussed through a theoretical model encompassing Maxwellian background ions and beam ions and non-Maxwellian κ-electrons. The ion beam velocity alone as a source is able to excite the KAWs up to a significant growth. The non-Maxwellian parameter κ impedes the growth of K…

The GALAH+ survey: a new library of observed stellar spectra improves radial velocities and hints at motions within M67

Lewis, Geraint F.; Ting, Yuan-Sen; Casey, Andrew R. +25 more

GALAH+ is a magnitude-limited survey of high-resolution stellar spectra obtained by the HERMES spectrograph at the Australian Astronomical Observatory. Its third data release provides reduced spectra with new derivations of stellar parameters and abundances of 30 chemical elements for 584 015 dwarfs and giants, 88 per cent of them in the Gaia magn…

Plasma densities, flow, and solar EUV flux at comet 67P. A cross-calibration approach

Nilsson, H.; Henri, P.; Edberg, N. J. T. +7 more

Context. During its two-year mission at comet 67P, Rosetta nearly continuously monitored the inner coma plasma environment for gas production rates varying over three orders of magnitude, at distances to the nucleus ranging from a few to a few hundred kilometres. To achieve the best possible measurements, cross-calibration of the plasma instrument…

Constraints on chameleon gravity from the measurement of the electrostatic stiffness of the M I C R O S C O P E mission accelerometers

Bergé, Joel; Pernot-Borràs, Martin; Uzan, Jean-Philippe +4 more

This article is dedicated to the use the MICROSCOPE mission's data to test chameleon theory of gravity. We take advantage of the technical sessions aimed to characterize the electrostatic stiffness of MICROSCOPE's instrument intrinsic to its capacitive measurement system. Any discrepancy between the expected and measured stiffness may result from …

The X-ray spectral and variability properties of typical radio-loud quasars

Brandt, W. N.; Zhu, S. F.; Timlin, John D.

We present X-ray spectral and long-term variability analyses of an unbiased sample of 361 optically selected radio-loud quasars (RLQs) utilizing sensitive serendipitous X-ray data from the Chandra and XMM-Newton archives. The spectral and temporal properties of RLQs are compared with those of radio-quiet quasars (RQQs) matched in L_2500Å…

Venus Atmospheric Dynamics at Two Altitudes: Akatsuki and Venus Express Cloud Tracking, Ground-Based Doppler Observations and Comparison with Modelling

Widemann, Thomas; Machado, Pedro; Peralta, Javier +6 more

Testing the models of X-ray driven photoevaporation with accreting stars in the Orion Nebula Cluster

Manara, C. F.; Preibisch, T.; Ercolano, B. +1 more

Context. Recent works highlight the importance of stellar X-rays on the evolution of the circumstellar disks of young stellar objects, especially for disk photoevaporation.
Aims: A signature of this process may be seen in the so far tentatively observed dependence of stellar accretion rates on X-ray luminosities. According to models of X-ray …

Resolved Nuclear Kinematics Link the Formation and Growth of Nuclear Star Clusters with the Evolution of Their Early- and Late-type Hosts

Böker, Torsten; Neumayer, Nadine; Emsellem, Eric +7 more

We present parsec-scale kinematics of 11 nearby galactic nuclei, derived from adaptive-optics assisted integral-field spectroscopy at (near-infrared) CO band-head wavelengths. We focus our analysis on the balance between ordered rotation and random motions, which can provide insights into the dominant formation mechanism of nuclear star clusters (…

Isochrone fitting of Galactic globular clusters - III. NGC 288, NGC 362, and NGC 6218 (M12)

Gontcharov, George A.; Mosenkov, Aleksandr V.; Khovritchev, Maxim Yu +6 more

We present new isochrone fits to colour-magnitude diagrams of the Galactic globular clusters NGC 288, NGC 362, and NGC 6218 (M12). We utilize a lot of photometric bands from the ultraviolet to mid-infrared by use of data from the HST, Gaia, unWISE, Pan-STARRS, and other photometric sources. In our isochrone fitting, we use theoretical models and i…

Large Adaptive Optics Survey for Substellar Objects around Young, Nearby, Low-mass Stars with Robo-AO

Baranec, Christoph; Duev, Dmitry A.; Jensen-Clem, Rebecca +16 more

We present results from the Large Adaptive optics Survey for Substellar Objects, where the goal is to directly image new substellar companions (<70 M_Jup) at wide orbital separations (≳50 au) around young (≲300 Myr), nearby (<100 pc), low-mass (≈0.1-0.8 ${M}_{\odot }$ ) stars. We report on 427 young stars imaged in the visible (i')…