Related papers: Leo5 Is a Z Cam Type Dwarf Nova
We present 30 new nearby (d<30 pc) red dwarf candidates, with estimated spectral types M6 to M8. 26 were directly selected from the DENIS database, and another 4 were first extracted from the LHS catalogue and cross-identified with a DENIS…
We present measurements of the periods of Dwarf Nova Oscillations (DNOs) and Quasi-Periodic Oscillations (QPOs) in Cataclysmic Variable stars (CVs), many culled from published literature, but also others newly observed (in VZ Pyx, CR Boo,…
Novae are found to have GeV to TeV gamma-ray emission, which reveals the shock acceleration from the white dwarfs. Recently, V1405 Cas was reported to radiated suspicious gamma-ray by \textit{Fermi}-LAT with low significance ($4.1 \sigma$)…
(Abridged) We present a large, uniform analysis of young (~10-150 Myr) ultracool dwarfs, based on new high-precision IR parallaxes for 68 objects. We find that low-gravity (VL-G) late-M and L dwarfs form a continuous sequence in IR…
We report the discovery of new member of the Local Group in the constellation of Antlia. Optically the system appears to be a typical dwarf spheroidal galaxy of type dE3.5 with no apparent young blue stars or unusual features. A…
Leo T ($M_V = -8.0$) is both the faintest and the least massive galaxy known to contain neutral gas and to display signs of recent star formation. We analyse photometry and stellar spectra to identify member stars and to better understand…
We present the discovery of Bo\"otes V, a new ultra-faint dwarf galaxy candidate. This satellite is detected as a resolved overdensity of stars during an ongoing search for new Local Group dwarf galaxy candidates in the UNIONS photometric…
I report the discovery of a new bright variable star in the constellation Scorpius. It is most likely star OGLE BUL-SC23 396060 with position (J2000.0): RA 17:57:59.75, DEC -31:38:07.4. Magnitude range is 14.4 (B) - 21.7 (V). It is visible…
We present early spectral observations of the very slow Galactic nova Gaia22alz, over its gradual rise to peak brightness that lasted 180 days. During the first 50 days, when the nova was only 3--4 magnitudes above its normal brightness,…
We report the discovery of the L dwarf WISE J174102.78$-$464225.5, that was discovered as part of a search for nearby L dwarfs using the Wide-field Infrared Survey Explorer (WISE). The distinct triangular peak of the H-band portion of its…
Doppler velocity measurements from the Anglo-Australian Planet Search reveal planetary mass companions to HD23127, HD159868, and a possible second planetary companion to HD154857. These stars are all G dwarfs. The companions are all in…
We report time-resolved photometric observations of the Hamburg Quasar Survey-selected dwarf nova HS 1449+6415 (= RX J1450.5+6403) during the interval from JD 2451672 to 2451724. During a long outburst with a duration of ~12 days, we…
A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in…
CONTEXT: The Nova V1405 Cas, which erupted on 18 March 2021, showed a pre-maximum phase of almost two months. After the main maximum, during several month the nova only weakened slightly and showed clear fluctuations in brightness. AIMS:…
Multi-frequency analysis has revealed the presence of a new supernova remnant, G55.0+0.3, in the Galactic plane. A kinematic distance of 14 kpc has been measured from HI spectral line data. The faint, clumpy half-shell is non-thermal and…
A radial velocity study of the cataclysmic variable ES Dra (PG 1524+622) is presented. ES Dra is found to have an orbital period of 0.17660 \pm 0.00006 d (4.2384 \pm 0.0014 h). The mass-losing secondary star of ES Dra is detectable in the…
We present observations of SDF-05M05, an unusual optical transient discovered in the Subaru Deep Field (SDF). The duration of the transient is > ~800 d in the observer frame, and the maximum brightness during observation reached…
We present multi-epoch near-infrared photo-spectroscopic observations of Nova Cephei 2014 and Nova Scorpii 2015, discovered in outburst on 2014 March 8.79 UT and 2015 February 11.84 UT respectively. Nova Cep 2014 shows the conventional NIR…
Light curves of the Z Cam type dwarf nova AT Cnc observed during standstill in 2016 and 2018 are analyzed. On the time scale of hours, previous reports on periodicities, in particular the presence of negative superhumps, could not be…
We present spectroscopic and photometric observations of 17 dwarf-nova superoutbursts obtained by KOOLS-IFU mounted on the 3.8 m telescope Seimei at Okayama Observatory of Kyoto University and through VSNET collaboration. Our spectroscopic…