- ID:
- ivo://CDS.VizieR/J/MNRAS/448/1551
- Title:
- JCMT Gould Belt Survey: Serpens MWC 297
- Short Name:
- J/MNRAS/448/1551
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450 and 850{mu}m observations of the Serpens MWC 297 region, part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey of nearby star-forming regions. Simulations suggest that radiative feedback influences the star formation process and we investigate observational evidence for this by constructing temperature maps. Maps are derived from the ratio of SCUBA-2 fluxes and a two-component model of the JCMT beam for a fixed dust opacity spectral index of {beta}=1.8. Within 40-arcsec of the B1.5Ve Herbig star MWC 297, the submillimetre fluxes are contaminated by free-free emission with a spectral index of 1.03+/-0.02, consistent with an ultracompact HII region and polar winds/jets. Contamination accounts for 73+/-5 per cent and 82+/-4 per cent of peak flux at 450{mu}m and 850 {mu}m, respectively. The residual thermal disc of the star is almost undetectable at these wavelengths. Young stellar objects (YSOs) are confirmed where SCUBA-2 850{mu}m clumps identified by the fellwalker algorithm coincide with Spitzer Gould Belt Survey detections. We identify 23 objects and use T_bol_ to classify nine YSOs with masses 0.09 to 5.1M_{sun}_. We find two Class 0, one Class 0/I, three Class I and three Class II sources. The mean temperature is 15+/-2K for the nine YSOs and 32+/-4K for the 14 starless clumps. We observe a starless clump with an abnormally high mean temperature of 46+/-2K and conclude that it is radiatively heated by the star MWC 297. Jeans stability provides evidence that radiative heating by the star MWC 297 may be suppressing clump collapse.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/4150
- Title:
- JCMT Gould Belt Survey: W40 complex
- Short Name:
- J/MNRAS/460/4150
- Date:
- 14 Jan 2022 11:14:19
- Publisher:
- CDS
- Description:
- We present SCUBA-2 450{mu}m and 850{mu}m observations of the W40 complex in the Serpens-Aquila region as part of the James Clerk Maxwell Telescope (JCMT) Gould Belt Survey (GBS) of nearby star-forming regions. We investigate radiative heating by constructing temperature maps from the ratio of SCUBA-2 fluxes using a fixed dust opacity spectral index, {beta}=1.8, and a beam convolution kernel to achieve a common 14.8-arcsec resolution. We identify 82 clumps ranging between 10 and 36K with a mean temperature of 20+/-3K. Clump temperature is strongly correlated with proximity to the external OB association and there is no evidence that the embedded protostars significantly heat the dust. We identify 31 clumps that have cores with densities greater than 10^5^cm^-3^. 13 of these cores contain embedded Class 0/I protostars. Many cores are associated with bright-rimmed clouds seen in Herschel 70{mu}m images. From JCMT HARP observations of the ^12^CO 3-2 line, we find contamination of the 850{mu}m band of up to 20 per cent. We investigate the free-free contribution to SCUBA-2 bands from large-scale and ultracompact HII regions using archival VLA data and find the contribution is limited to individual stars, accounting for 9 per cent of flux per beam at 450{mu}m or 12 per cent at 850{mu}m in these cases. We conclude that radiative heating has potentially influenced the formation of stars in the Dust Arc sub-region, favouring Jeans stable clouds in the warm east and fragmentation in the cool west.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A122
- Title:
- JHK and IRAC photometry of Sh2-90 YSOs
- Short Name:
- J/A+A/566/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the star formation activity in the molecular complex associated with the Galactic HII region Sh2-90. We obtain the distribution of the ionized and cold neutral gas using radio-continuum and Herschel observations. We use near-infrared and Spitzer data to investigate the stellar content of the complex. We discuss the evolutionary status of embedded massive young stellar objects (MYSOs) using their spectral energy distribution.
- ID:
- ivo://CDS.VizieR/J/ApJ/672/398
- Title:
- JHK' photometry of M17 silhouette object
- Short Name:
- J/ApJ/672/398
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study how the structure of the envelopes of young stellar objects (YSOs) evolve, we carried out a deep JHK'-band imaging survey of the M17 star-forming region using a near-infrared camera and the Infrared Camera and Spectrograph with adaptive optics mounted on the Subaru Telescope. In this survey, we found 51 dark silhouettes against bright near-infrared nebula emissions as background lights. They are regarded as envelopes associated with YSOs due to their size and association with the YSOs. We derived size, morphology, extinction, and mass for each silhouette envelope.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/1196
- Title:
- JHKs light curves of 2MASS J05352184-0546085
- Short Name:
- J/ApJ/699/1196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-infrared JHK_S_ light curves for the double-lined eclipsing binary system Two Micron All Sky Survey J05352184-0546085, in which both components have been shown to be brown dwarfs with an age of ~1Myr. We analyze these light curves together with the previously published I_C_-band light curve and radial velocities to provide refined measurements of the system's physical parameters. The component masses and radii are here determined with an accuracy of ~6.5% and ~1.5%, respectively. In addition, we confirm the previous surprising finding that the primary brown dwarf has a cooler effective temperature than its lower mass companion. Our analysis reveals two low-amplitude (~0.02mag) periodic signals, one attributable to the rotation of the primary with a period of 3.293+/-0.001d and the other to the rotation of the secondary with a period of 14.05+/-0.05d. Both periods are consistent with the measured vsin i and radii.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/42
- Title:
- JHKs polarimetry in Circinus Molecular Cloud
- Short Name:
- J/ApJS/234/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of near-infrared (NIR) linear imaging polarimetry in the J, H, and Ks bands of the low-mass star cluster-forming region in the Circinus Molecular Cloud Complex. Using aperture polarimetry of point-like sources, positive detection of 314, 421, and 164 sources in the J, H, and Ks bands, respectively, was determined from among 749 sources whose photometric magnitudes were measured. For the source classification of the 133 point-like sources whose polarization could be measured in all 3 bands, a color-color diagram was used. While most of the NIR polarizations of point-like sources are well-aligned and can be explained by dichroic polarization produced by aligned interstellar dust grains in the cloud, 123 highly polarized sources have also been identified with some criteria. The projected direction on the sky of the magnetic field in the Cir-MMS region is indicated by the mean polarization position angles (70{deg}) of the point-like sources in the observed region, corresponding to approximately 1.6x1.6pc^2^. In addition, the magnetic field direction is compared with the outflow orientations associated with Infrared Astronomy Satellite sources, in which two sources were found to be aligned with each other and one source was not. We also show prominent polarization nebulosities over the Cir-MMS region for the first time. Our polarization data have revealed one clear infrared reflection nebula (IRN) and several candidate IRNe in the Cir-MMS field. In addition, the illuminating sources of the IRNe are identified with near- and mid-infrared sources.
- ID:
- ivo://CDS.VizieR/J/other/PASA/26.439
- Title:
- K-band images of star-forming regions
- Short Name:
- J/other/PASA/26.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep, wide-field, Ks-band (2.14-micron) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14-micron point source catalogues (PSCs) towards each of the regions. For the regions between 10{deg}<l<350{deg} and |b|<1, we match the 2.14-micron sources with the GLIMPSE point source catalogue to generate a combined 2.14- to 8.0-micron point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/156/71
- Title:
- K2 Campaign 2: young disk-bearing stars in Sco & Oph
- Short Name:
- J/AJ/156/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The K2 Mission has photometrically monitored thousands of stars at high precision and cadence in a series of ~80-day campaigns focused on sections of the ecliptic plane. During its second campaign, K2 targeted over 1000 young stellar objects (YSOs) in the ~1-3 Myr {rho} Ophiuchus and 5-10 Myr Upper Scorpius regions. From this set, we have carefully vetted photometry from WISE and Spitzer to identify those YSOs with infrared excess indicative of primordial circumstellar disks. We present here the resulting comprehensive sample of 288 young disk-bearing stars from B through M spectral types and analysis of their associated K2 light curves. Using statistics of periodicity and symmetry, we categorize each light curve into eight different variability classes, notably including "dippers" (fading events), "bursters" (brightening events), stochastic, and quasi-periodic types. Nearly all (96%) of disk-bearing YSOs are identified as variable at 30-minute cadence with the sub-1% precision of K2. Combining our variability classifications with (circum)stellar properties, we find that the bursters, stochastic sources, and the largest amplitude quasi-periodic stars have larger infrared colors, and hence stronger circumstellar disks. They also tend to have larger H{alpha} equivalent widths, indicative of higher accretion rates. The dippers, on the other hand, cluster toward moderate infrared colors and low H{alpha}. Using resolved disk observations, we further find that the latter favor high inclinations, except for a few notable exceptions with close to face-on disks. These observations support the idea that YSO time-domain properties are dependent on several factors, including accretion rate and view angle.
- ID:
- ivo://CDS.VizieR/J/AJ/150/32
- Title:
- KELT 2006-2013 photometry of V409 Tau and AA Tau
- Short Name:
- J/AJ/150/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AA Tau is a well studied young stellar object (YSO) that presents many of the photometric characteristics of a Classical T Tauri star (CTTS), including short-timescale stochastic variability attributed to spots and/or accretion as well as long-duration dimming events attributed to occultations by vertical features (e.g., warps) in its circumstellar disk. We present new photometric observations of AA Tau from the Kilodegree Extremely Little Telescope North (KELT-North) which reveal a deep, extended dimming event in 2011, which we show supports the interpretation by Bouvier et al. of an occultation by a high-density feature in the circumstellar disk located >8AU from the star. We also present KELT-North observations of V409 Tau, a relatively unstudied YSO also in Taurus-Auriga, showing short timescale erratic variability, along with two separate long and deep dimming events, one from 2009 January through late 2010 October, and the other from 2012 March until at least 2013 September. We interpret both dimming events to have lasted more than 600 days, each with a depth of ~1.4mag. From a spectral energy distribution analysis, we propose that V409 Tau is most likely surrounded by a circumstellar disk viewed nearly edge-on, and using Keplerian timescale arguments we interpret the deep dimmings of V409 Tau as occultations from one or more features within this disk >~10AU from the star. In both AA Tau and V409 Tau, the usual CTTS short-timescale variations associated with accretion processes close to the stars continue during the occultations, further supporting the distant occulting material interpretation. Like AA Tau, V409 Tau serves as a laboratory for studying the detailed structure of the protoplanetary environments of T Tauri disks, specifically disk structures that may be signposts of planet formation at many AU out in the disk. We also provide a table of all currently known disk-occulting young stars as a convenient reference for future work on such objects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/366/1096
- Title:
- Kinematic distance ambiguity
- Short Name:
- J/MNRAS/366/1096
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the use of HI data to resolve the near/far ambiguity in kinematic distances of massive young stellar object (MYSO) candidates. Kinematic distances were obtained from ^13^CO 1-0 (and N_2_H^+^) spectral-line observations with the Mopra Telescope towards 94 candidates selected from the Red MSX Source (RMS) survey in the fourth Galactic quadrant (282{deg}<l<350{deg}). HI data from the Southern Galactic Plane Survey (SGPS) were used in conjunction with the HI self-absorption (SA) technique to determine the near or far distance. We resolved the kinematic distance ambiguity to 70 per cent of the sources. We can also simultaneously solve for any multiple line-of-sight component sources. We discuss the advantages and disadvantages of this technique in comparison with other methods, and also perform confidence checks on the reliability of using the HI SA technique.
