Related papers: V1117 Her: A Herbig Ae star at high Galactic latit…
Herbig Ae/Be stars are young contracting stars on the radiative track in the HR diagram on their way to the main sequence. These stars provide a valuable link between high and low mass stars. Here we review the progress that has been made…
V503 Her was previously proposed as an eclipsing symbiotic candidate based on photometric behavior and spectroscopic appearance indicating the composite optical spectrum. To investigate its nature, we analyzed long-term photometric…
The dipper optical light curves in young stellar objects are commonly interpreted as partial or total occultation of the stellar radiation by dust surrounding the star. In this work, we analyze the amplitude of the optical light curve of…
The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD142527, for which previous observations revealed a complex…
We analyze the historical light curve of the symbiotic star YY Her, from 1890 up to December 2005. A secular declining trend is detected, at a rate of ~.01 magn in 1000 d, suggesting that the system could belong to the sub-class of…
EPIC 204278916 has been serendipitously discovered from its K2 light curve which displays irregular dimmings of up to 65% for ~25 consecutive days out of 78.8 days of observations. For the remaining duration of the observations, the…
We are conducting a comprehensive investigation of V815 Her using photometric and spectroscopic data to understand the origin of the activity and what influences it in the short and long term. Using TESS photometry we performed light curve…
V Hya, an evolved carbon star with a complex circumstellar envelope, has two variability periods, 530d and 6000d (17 years). We analyze recent light curve data and show that both variations have benn present for at least 100 years and have…
Context. V2492 Cyg is a young eruptive star that went into outburst in 2010. The near-infrared color changes observed since the outburst peak suggest that the source belongs to a newly defined sub-class of young eruptive stars, where…
The well studied carbon star V Hydrae is known to exhibit a complex asymmetric environment made of a dense equatorial wind and high-velocity outflows, hinting at its transition from the AGB phase to the asymmetric planetary nebula phase. In…
The Galactic Center provides a unique opportunity to observe a galactic core, objects in close proximity to a supermassive black hole (SMBH), and star formation channels that exhibit imprints of this peculiar environment. This habitat…
It is known that scattering of radiation by circumstellar dust can strongly change the line profiles in stellar spectra. This hampers the analysis of spectral lines originating in the emitting regions of heavily obscured young stars. To…
Young stars with masses 2-8 Suns, called the Herbig Ae and Be stars, often show a near-infrared excess too large to explain with a hydrostatically-supported circumstellar disk of gas and dust. At the same time the accretion flow carrying…
We present new high and low resolution spectroscopic and photometric data of nine members of the young association CMa R1. All the stars have circumstellar dust at some distance as could be expected from their association with reflection…
We report the discovery of the optical dipper and low-luminosity infrared stellar transient Gaia20ehk (hereafter, Gaia-GIC-1), which is currently undergoing high-amplitude variability due to transiting dusty material. In this work, we…
Young double star V1318 Cyg, which is associated with a small isolated star-forming region around HAeBe star BD+40o4124, has very unusual photometric and spectral behavior. We present results of photometric and spectroscopic observations in…
Isolated HAEBE stars are believed to represent an intermediate stage of objects between young stellar objects surrounded by massive, optically thick, gaseous and dusty disks and Vega like stars surrounded by debris disks. The star AB Aur is…
BVR light curves and radial velocities for the double-lined eclipsing binary V1135\,Her were obtained. The brighter component of V1135\,Her is a Cepheid variable with a pulsation period of 4.22433$\pm$0.00026 days. The orbital period of the…
The Herbig Ae star PDS2 (CD -53 251) is unusual in several ways. It has a high Galactic latitude, unrelated to any known star-forming region. It is at the cool end of the Herbig Ae sequence, where favorable circumstances facilitate the…
In this work, we analyze the ongoing brightening of the poorly studied symbiotic star V4141 Sgr and examine its long-term variability. We present new low-resolution spectroscopic observations of the system in its bright state and combine…