- ID:
- ivo://CDS.VizieR/J/AJ/120/333
- Title:
- UBVRI and H{alpha} in NGC 6530
- Short Name:
- J/AJ/120/333
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New UBVRI and H{alpha} photometry has been obtained for the young open cluster NGC 6530 located 10' east of the Lagoon Nebula (M8). We found 37 pre-main-sequence (PMS) stars with H{alpha} emission and nine PMS candidates using the R-H{alpha} color, a measure of H{alpha} emission. From this new photometry we derived the cluster parameters (V_0_-M_V_=11.25+/-0.1mag and E(B-V)=0.35mag), typical age (1.5Myr), and an age spread of about 5Myr. We confirmed the presence of a small amount of differential reddening across the cluster. We also verified the abnormal reddening law for the cluster, especially for a heavily embedded O7 V star, Herschel 36. Comparisons were made for several PMS evolution models with regard to the resulting age distribution and the initial mass function.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/320/185
- Title:
- UBVRIcJHKL photometry in Lup
- Short Name:
- J/A+A/320/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a recent study, some 130 new weak-line T Tauri stars (WTTS) have been discovered in the Lupus star forming region (SFR). Some of these stars are seen projected onto regions of high obscuration, while others are located far from the Lupus dark clouds. In this paper we present photometric observations of a large sample of these WTTS. We estimate effective temperatures and luminosities for the stars observed, and derive masses and ages by comparison with theoretical evolutionary tracks. The photometric observations were performed at the ESO 1 m-Telescope during two observing runs in 1993 (March 10-12) and 1994 (May 1-6) at ESO, La Silla. The typical standard deviations are 0.01mag in V, 0.02mag in B-V, 0.04mag in U-B, 0.01 in V-R and V-I. For a description of the UBV, (RI)c and JHKL photometric systems, see e.g. <GCPD/01>, <GCPD/54> and <GCPD/09>
- ID:
- ivo://CDS.VizieR/J/A+A/511/A25
- Title:
- UBVRIH{alpha} photometry of NGC6383
- Short Name:
- J/A+A/511/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The very young open cluster NGC 6383 centered on the O-star binary HD 159176 is an interesting place for studying the impact of early-type stars with strong radiation fields and powerful winds on the formation processes of low-mass stars. To investigate this process, it is necessary to determine the characteristics (age, presence, or absence of circumstellar material) of the population of low-mass pre-main-sequence (PMS) stars in the cluster. We obtained deep U B V Rc Ic H{alpha} photometric data of the entire cluster as well as medium-resolution optical spectroscopy of a subsample of X-ray selected objects. Our spectroscopic data reveal only very weak H{alpha} emission lines in a few X-ray selected PMS candidates. We photometrically identify a number of H-{alpha} emission candidates but their cluster membership is uncertain. We find that the fainter objects in the field of view have a wide range of extinction (up to A_V_=20), one X-ray selected OB star having A_V_~8. Our investigation uncovers a population of PMS stars in NGC 6383 that are probably coeval with HD 159176. In addition, we detect a population of reddened objects that are probably located at different depths within the natal molecular cloud of the cluster. Finally, we identify a rather complex spatial distribution of H{alpha} emitters, which is probably indicative of a severe contamination by foreground and background stars.
- ID:
- ivo://CDS.VizieR/J/AJ/114/2644
- Title:
- UBVRIHa photometry of NGC2264
- Short Name:
- J/AJ/114/2644
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI H{alpha} CCD photometry has been obtained fro the young cluster NGC 2264. Using (R-H{alpha}) color, a measure of H{alpha} emission, we selected member stars in the pre-main sequence (PMS) stage.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A104
- Title:
- UBVRIJHK photometry of Dolidze 25
- Short Name:
- J/A+A/509/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of our deep UBVRIJHK photometry of Dolidze 25, located in the central area of the HII region Sh 2-284, reveals a young cluster with coeval MS and PMS populations of age 3.2-5Myr. The mass function for the optical PMS population in the mass range above 1.3-3.5M_{sun}_ is well fitted by a Salpeter mass function. On the other hand, the NIR photometry results indicate a large number of sources with H-Ks excess, practically distinct from the optical PMS candidate members. In addition, a distinctly older cluster member population of age 40Myr is suggested. The distance determined for the cluster from quantitative fits to ZAMS and isochrones (3.6kpc) is distinctly lower than previously published values. This result originates in the consistent use of low metallicity models for ZAMS fitting, applying published metallicity values for the cluster
- ID:
- ivo://CDS.VizieR/J/AJ/126/2971
- Title:
- UBVRI photometry of 131 Herbig Ae/Be
- Short Name:
- J/AJ/126/2971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 108 Herbig Ae/Be candidate stars identified in the Pico dos Dias Survey (Gregorio-Hete et al., 1992AJ....103..549G; Torres et al., 1995AJ....109.2146T and 1999, Special Publ. 10, Rio de Janeiro: Obs. Nac.), together with 19 previously known candidates and four objects selected from the IRAS Faint Source Catalog (<II/156>). These 131 stars were observed with low- and/or medium-resolution spectroscopy, and we complement these data with high-resolution spectra of 39 stars.
- ID:
- ivo://CDS.VizieR/J/A+A/479/827
- Title:
- UBVR light curves of weak-line T Tauri stars
- Short Name:
- J/A+A/479/827
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- T Tauri stars exhibit variability on all timescales, whose origin is still debated. On WTTS the variability is fairly simple and attributed to long-lived, ubiquitous cool spots. We investigate the long term variability of WTTS, extending up to 20 years in some cases, characterize it statistically and discuss its implications for our understanding of these stars. We have obtained a unique, homogeneous database of photometric measurements for WTTS extending up to 20-years. It contains more than 9000 UBVR observations of 48 WTTS. All the data were collected at Mount Maidanak Observatory (Uzbekistan) and they constitute the longest homogeneous record of accurate WTTS photometry ever assembled. Definitive rotation periods for 35 of the 48 stars are obtained. Phased light curves over 5 to 20 seasons are now available for analysis. Light curve shapes, amplitudes and colour variations are obtained for this sample and various behaviors exhibited, discussed and interpreted. Our main conclusion is that most WTTS have very stable long term variability with relatively small changes of amplitude or mean light level. The long term variability seen reflects modulation in the cold spot distributions. Photometric periods are stable over many years, and the phase of minimum light can be stable as well for several years. On the long term, spot properties do change in subtle ways, leading to secular variations in the shape and amplitudes of the light curves.
- ID:
- ivo://CDS.VizieR/J/MNRAS/503/270
- Title:
- UKIDSS JHK photometry of W33A
- Short Name:
- J/MNRAS/503/270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- W33A is a well-known example of a high-mass young stellar object showing evidence of a circumstellar disc. We revisited the -band NIFS/Gemini North observations of the W33A protostar using principal components analysis tomography and additional post-processing routines. Our results indicate the presence of a compact rotating disc based on the kinematics of the CO absorption features. The position-velocity diagram shows that the disc exhibits a rotation curve with velocities that rapidly decrease for radii larger than 0.1" (~250AU) from the central source, suggesting a structure about four times more compact than previously reported.We derived a dynamical mass of 10.0^+4.1^_-2.2_M_{sun}_ for the "disc+protostar" system, about ~33% smaller than previously reported, but still compatible with high-mass protostar status. A relatively compact H_2_ wind was identified at the base of the large-scale outflow of W33A, with a mean visual extinction of ~63mag. By taking advantage of supplementary near-infrared maps, we identified at least two other point-like objects driving extended structures in the vicinity of W33A, suggesting that multiple active protostars are located within the cloud. The closest object (SourceB) was also identified in the NIFS field of view as a faint pointlike object at a projected distance of ~7000AU from W33A, powering extended K-band continuum emission detected in the same field. Another source (SourceC) is driving a bipolar H_2_ jet aligned perpendicular to the rotation axis of W33A.
- ID:
- ivo://CDS.VizieR/J/A+AS/101/59
- Title:
- 1-20um observations of Herbig-Haro objects
- Short Name:
- J/A+AS/101/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For 58 exciting sources of Herbig-Haro objects/jets (HHES) we present a catalogue of photometric data for the infrared spectral bands JHKLMNQ (1-20 um). This catalog is based on our own observations and published information available up to May 1992. For each source, these data are presented in chronological order. In addition to the broad-band data, narrow-band N(8-13 um) photometric data are also provided. The flux calibration for each observational equipment is explicitly noted as the diaphragm sizes are used. The same kind of information for the established members of the FU Ori class is complementing the HHES catalogue. The frequency of observations and the photometric quality of the catalogued data are shortly discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/333/619
- Title:
- Upper Scorpius OB association Lithium survey
- Short Name:
- J/A+A/333/619
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an intermediate resolution spectroscopic survey for pre-main sequence (PMS) stars in the Upper Scorpius OB association. In a 160 square-degree area we were able to identify 39 new PMS stars by follow up observations of X-ray selected stars with the multi object spectrograph FLAIR at the UK Schmidt Telescope. We also investigated the completeness of our X-ray selected sample by observing more than 100 stars that were not detected as X-ray sources, but have proper motions indicating membership to Upper Sco. While the new X-ray selected PMS stars with known proper motions have kinematics consistent with membership, none of the X-ray quiet proper motion candidates is a PMS star. We conclude that our X-ray selected sample of PMS stars seems to be rather complete. For stars in the magnitude interval 11.5<~B<~13.5 we derive a conservative lower limit of 75% completeness.
