We present the star formation activity around the emission nebula Sh2-112. At a distance of ∼2.1 kpc, this H ii complex, itself 3 pc in radius, is illuminated by the massive star (O8 V) BD+45 3216. The associated molecular cloud extends in angular scales of 2.°0 × 0.°83, corresponding to linear sizes of 73 pc by 30 pc, along the Galactic longitude. The high-resolution (30″) extinction map reveals a chain of dust clumps aligned with the filament-like structure with an average extinction of A V ∼ 2.78 mag, varying up to a maximum of ∼17 mag. Our analysis led to identification of a rich population (∼500) of young (average age of ∼1 Myr) stars, plus a numerous number (∼350) of Hα emitters, spatially correlated with the filamentary clouds. Located near the edge of the cloud, the luminous star BD+45 3216 has created an arc-like pattern as the ionizing radiation encounters the dense gas, forming a blister-shaped morphology. We found three distinct young stellar groups, all coincident with relatively dense parts of the cloud complex, signifying ongoing star formation. Moreover, the cloud filament (excitation temperature ∼10 K) traced by the CO isotopologues and extending nearly ∼80 pc is devoid of ionized gas except at the dense cores (excitation temperature ∼28–32 K) wherein significant ionized emission excited by OB stars (dynamical age ∼0.18–1.0 Myr) pertains. The radial velocity is dynamic (median ∼−3.65 km s−1) along the main filament, increasing from Galactic east to west, indicating mass flow to form the massive stars/clusters at the central hubs.

We present here identification and characterization of the young stellar population associated with an active star-forming site Sh2-242. We used our own new optical imaging and spectroscopic observational data, as well as several archival catalogs, e.g., Pan-STARRS 1, Gaia DR2, IPHAS, WIRCam, 2MASS, and Spitzer. Slit spectroscopic results confirm the classification of the main ionizing source BD+26 980 as an early-type star of spectral type B0.5 V. The spectrophotometric distance of the star is estimated as 2.08 ± 0.24 kpc, which confirms the source as a member of the cluster. An extinction map covering a large area (diameter ∼ 50 ) is generated with H and K photometry toward the region. From the map, three distinct locations of peak extinction complexes (A V 7-17 mag) are identified for the very first time. Using the infrared color excess, a total of 33 Class I and 137 Class II young objects are classified within the region. The IPHAS photometry reveals classification of 36 Hα emitting sources, which might be class II objects. Among 36 Hα emitting sources, 5 are already identified using infrared excess emission. In total, 201 young objects are classified toward S242 from this study. The membership status of the young sources is further windowed with the inclusion of parallax from the Gaia DR2 catalog. Using the optical and infrared color-magnitude diagrams, the young stellar objects are characterized with an average age of ∼ 1 Myr and the masses in the range 0.1-3.0 M . The census of the stellar content within the region is discussed using combined photometric and spectroscopic data.

We present here optical I-band photometric variability study down to ≃ 19 mag of a young (∼2-3 Myr) star-forming region IC 348 in the Perseus molecular cloud. We aim to explore the fast rotation (in the time-scales of hours) in Very Low Mass stars (VLMs) including Brown Dwarfs (BDs). From a sample of 177 light-curves using our new I-band observations, we detect new photometric variability in 22 young M-dwarfs including 6 BDs, which are bonafide members in IC 348 and well-characterized in the spectral type of M-dwarfs. Out of 22 variables, 11 M dwarfs including one BD show hour-scale periodic variability in the period range 3.5 - 11 hours and rest are aperiodic in nature. Interestingly, an optical flare is detected in a young M2.75 dwarf in one night data on 20 December 2016. From the flare light curve, we estimate the emitted flared energy of 1.48 × 1035 ergs. The observed flared energy with an uncertainty of tens of per cent is close to the super-flare range (∼ 1034 ergs), which is rarely observed in active M dwarfs.

We present comprehensive characterization of the Galactic open cluster M 36. Some 200 member candidates, with an estimated contamination rate of ∼8%, have been identified on the basis of proper motion and parallax measured by the Gaia DR2. The cluster has a proper motion grouping around ( mas yr−1, and μ δ = − 3.35 ± 0.02 mas yr−1), distinctly separated from the field population. Most member candidates have parallax values 0.7–0.9 mas, with a median value of 0.82 ± 0.07 mas (distance ∼1.20 ± 0.13 kpc). The angular diameter of determined from the radial density profile then corresponds to a linear extent of 9.42 ± 0.14 pc. With an estimated age of ∼15 Myr, M 36 is free of nebulosity. To the southwest of the cluster, we discover a highly obscured (A V up to ∼23 mag), compact (∼ ) dense cloud, within which three young stellar objects in their infancy (ages ≲0.2 Myr) are identified. The molecular gas, 3.6 pc in extent, contains a total mass of (2–3) × 102 M ⊙, and has a uniform velocity continuity across the cloud, with a velocity range of −20 to −22 km s−1, consistent with the radial velocities of known star members. In addition, the cloud has a derived kinematic distance marginally in agreement with that of the star cluster. If physical association between M 36 and the young stellar population can be unambiguously established, this manifests a convincing example of prolonged star formation activity spanning up to tens of Myr in molecular clouds.

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