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Testing the accretion scenario of λ Boo stars
Angeloni, R.; Jaque Arancibia, M.; Veramendi, M. E. +5 more
Context. The existence of a group of λ Boo stars has been known for years, however, the origin of its chemical peculiarity is still a matter of debate.
Aims: Our aim is to test the accretion scenario of λ Boo stars. This model predicts that in a binary system with two early-type stars passing through a diffuse cloud, both stars ought to displ…
Kinematic characteristics of the Milky Way globular clusters based on Gaia DR2 data
Chemerynska, I. V.; Ishchenko, M. V.; Sobolenko, M. O. +2 more
Using the data from Gaia (ESA) Data Release 2 we performed the orbital calculations of globular clusters (GCs) of the Milky Way. To explore possible close encounters (or collisions) between the GCs, using our own developed high-order φ-GRAPE code, we integrated backward and forward orbits of 119 objects with reliable positions and proper motions. …
Hα spectroscopy of the recurrent nova RS Oph during the 2021 outburst
Stoyanov, K. A.; Marchev, D.; Zamanov, R. K. +3 more
We report spectroscopic observations of the Hα emission line of the recurrent nova RS~Oph obtained between 2021 August 12 and 2021 August 23 during the recent outburst. On the basis of the sharp P~Cyg profile superimposed onto the strong Hα emission, we estimate that the outflowing velocity of the material surrounding RS~Oph is in the range 32 km …
BepiColombo Mio Observations of Low-Energy Ions During the First Mercury Flyby: Initial Results
Persson, Moa; Saito, Yoshifumi; Delcourt, Dominique +14 more
We present initial results of low-energy ion observations from BepiColombo's first Mercury flyby. Unprecedentedly high time resolution measurements of low energy ions at Mercury by BepiColombo Mio reveal rapid (a few seconds) and large (1-2 orders of magnitude) fluctuations of ion flux around the magnetopause and within the magnetosphere. Around t…
KK 242, A Faint Companion to the Isolated Scd Galaxy NGC 6503
Cannon, John M.; Anand, Gagandeep S.; Tully, R. Brent +4 more
Using Hubble Space Telescope imaging of the resolved stellar population of KK 242 = NGC 6503-d1 =PGC 4689184, we measure the distance to the galaxy to be 6.46 ± 0.32 Mpc and find that KK 242 is a satellite of the low-mass spiral galaxy NGC 6503 located on the edge of the Local Void. Observations with the Karl G. Jansky Very Large Array show signs …
The Effect of Molecular Cloud Properties on the Kinematics of Stars Formed in the Trifid Region
Gromadzki, Mariusz; Feigelson, Eric D.; Hillenbrand, Lynne A. +5 more
The dynamical states of molecular clouds may affect the properties of the stars they form. In the vicinity of the Trifid Nebula (d = 1180 ± 25 pc), the main star cluster (Trifid Main) lies within an expanding section of the molecular cloud; however, ~0.°3 to the north (Trifid North), the cloud's velocity structure is more tranquil. We acquired a C…
The OGLE Collection of Variable Stars. Over 2600 δ Scuti Stars in the Small Magellanic Cloud
Soszyński, I.; Udalski, A.; Szymański, M. K. +11 more
We present the first-ever collection of δ Scuti stars found over the entire area of the Small Magellanic Cloud (SMC). The sample consists of 2810 variables of which over 2600 objects belong to the SMC while the remaining stars are most likely members of the Milky Way's halo. The sample has been divided into 2733 single mode and 77 multimode pulsat…
Paleolake Inlet Valley Formation: Factors Controlling Which Craters Breached on Early Mars
Fassett, C. I.; Bamber, Emily R.; Goudge, T. A. +2 more
The ancient surface of Mars is dominated by degraded impact craters with reduced or eliminated rim relief. Some degraded craters have an inlet valley, while many remain fluvially isolated. Despite controlling Martian fluvial connectivity, few constraints exist on why some—but not all—degraded craters possess inlets. We compared a suite of properti…
Predicted trends in Milky Way bulge proper motion rotation curves: future prospects for HST and LSST
Gennaro, Mario; Clarkson, William I.; Sahu, Kailash C. +5 more
We use an N-body+smoothed particle hydrodynamics simulation of an isolated barred galaxy to study the age dependence of bulge longitudinal proper motion (µl) rotation curves. We show that close to the minor axis (|l| ~ 0○) the relatively young stars rotate more rapidly than the old stars, as found by Hubble Space Telesc…
Chandra Observations of Six Peter Pan Disks: Diversity of X-Ray-driven Internal Photoevaporation Rates Does Not Explain Their Rare Longevity
Kounkel, Marina; Kuchner, Marc J.; Wisniewski, John P. +6 more
We present Chandra X-ray observations of six previously identified Peter Pan objects, rare ∼40 Myr systems with evidence of primordial disk retention. We observe X-ray luminosities (0.8–3.0 keV) ranging from log L x ∼ 27.7–29.1. We find that our Peter Pan sample exhibits X-ray properties similar to that of weak-lined T Tauri stars and…