- ID:
- ivo://CDS.VizieR/J/ApJ/709/L114
- Title:
- Protoplanetary disks in PMS binaries
- Short Name:
- J/ApJ/709/L114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this Letter, I examine several observational trends regarding protoplanetary disks, debris disks, and exoplanets in binary systems in an attempt to constrain the physical mechanisms of planet formation in such a context. Binaries wider than about 100AU are indistinguishable from single stars in all aspects. Binaries in the 5-100AU range, on the other hand, are associated with shorter lived but (at least in some cases) equally massive disks. Furthermore, they form planetesimals and mature planetary systems at a similar rate as wider binaries and single stars, albeit with the peculiarity that they predominantly produce high-mass planets. I posit that the location of a stellar companion influences the relative importance of the core accretion and disk fragmentation planet formation processes, with the latter mechanism being predominant in binaries tighter than 100AU.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/897/L38
- Title:
- Protostars exitation temperature in literature
- Short Name:
- J/ApJ/897/L38
- Date:
- 14 Mar 2022 07:04:15
- Publisher:
- CDS
- Description:
- Earth's carbon deficit has been a persistent problem in our understanding of the formation of our solar system. A possible solution would be the sublimation of carbon grains at the so-called soot line (~300K) early in the planet-formation process. Here, we argue that the most likely signatures of this process are an excess of hydrocarbons and nitriles inside the soot line, and a higher excitation temperature for these molecules compared to oxygen-bearing complex organics that desorb around the water snowline (~100K). Such characteristics have been reported in the literature, for example, in Orion KL, although not uniformly, potentially due to differences in the observational settings and analysis methods of different studies or the episodic nature of protostellar accretion. If this process is active, this would mean that there is a heretofore unknown component to the carbon chemistry during the protostellar phase that is acting from the top down-starting from the destruction of larger species-instead of from the bottom up from atoms. In the presence of such a top-down component, the origin of organic molecules needs to be re-explored.
- ID:
- ivo://CDS.VizieR/J/ApJ/692/973
- Title:
- Protostars in Perseus, Serpens and Ophiuchus
- Short Name:
- J/ApJ/692/973
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an unbiased census of deeply embedded protostars in Perseus, Serpens, and Ophiuchus, assembled by combining large-scale 1.1mm Bolocam continuum and Spitzer Legacy surveys. We identify protostellar candidates based on their mid-infrared (mid-IR) properties, correlate their positions with 1.1mm core positions from Enoch et al. in 2006 (Cat. J/ApJ/638/293) and 2007ApJ...666..982E, and Young et al. in 2006ApJ...644..326Y, and construct well-sampled spectral energy distributions using our extensive wavelength coverage ({lambda}=1.25-1100um). Source classification based on the bolometric temperature yields a total of 39 Class 0 and 89 Class I sources in the three-cloud sample. We compare to protostellar evolutionary models using the bolometric temperature-luminosity diagram, finding a population of low-luminosity Class I sources that are inconsistent with constant or monotonically decreasing mass accretion rates.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/606
- Title:
- Protostars in the Vela Molecular Cloud
- Short Name:
- J/ApJ/704/606
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the infrared variability of young stellar objects by means of two Spitzer-IRAC images of the Vela Molecular Cloud D (VMR-D) obtained in observations separated in time by about six months. By using the same space-born IR instrumentation, this study eliminates all the unwanted effects due to differences in sensitivity, confusion, saturation, calibration, and filter bandpasses, issues that are usually unavoidable when comparing catalogs obtained from different instruments. The VMR-D map covers about 1.5deg^2^ of a site where star formation is actively ongoing. We are interested in accreting pre-main sequence variables whose luminosity variations are due to intermittent events of disk accretion (i.e., active T Tauri stars and EXor-type objects). The variable objects have been selected from a catalog of more than 170000 sources detected at an S/N>=5 (Cat. J/ApJ/719/9). We then searched the sample of variables for ones whose photometric properties such as IR excess, color-magnitude relationships, and spectral energy distribution, are as close as possible to those of known EXor's. Indeed, the latter are monitored in a more systematic way than T Tauri stars and the mechanisms that regulate the observed phenomenology are exactly the same. Hence, the modalities of the EXor behavior are adopted as driving criterion for selecting variables in general. We ultimately selected 19 bona fide candidates that constitute a well defined sample of new variable targets for further investigation (monitoring, spectroscopy). Out of these, 10 sources present a Spitzer MIPS 24um counterpart, and have been classified as three Class I, five flat spectrum, and two Class II objects, while the spectral energy distribution of the other nine sources is compatible with evolutionary phases older than Class I.
- ID:
- ivo://CDS.VizieR/J/AJ/162/56
- Title:
- Radial velocity of 240 YSOs with MMT/Hectochelle
- Short Name:
- J/AJ/162/56
- Date:
- 14 Mar 2022 06:56:34
- Publisher:
- CDS
- Description:
- Stellar kinematics is a powerful tool for understanding the formation process of stellar associations. Here, we present a kinematic study of the young stellar population in the Rosette nebula using recent Gaia data and high-resolution spectra. We first isolate member candidates using the published mid-infrared photometric data and the list of X-ray sources. A total of 403 stars with similar parallaxes and proper motions are finally selected as members. The spatial distribution of the members shows that this star-forming region is highly substructured. The young open cluster NGC2244 in the center of the nebula has a pattern of radial expansion and rotation. We discuss its implication on the cluster formation, e.g., monolithic cold collapse or hierarchical assembly. On the other hand, we also investigate three groups located around the border of the HII bubble. The western group seems to be spatially correlated with the adjacent gas structure, but their kinematics is not associated with that of the gas. The southern group does not show any systematic motion relative to NGC2244. These two groups might be spontaneously formed in filaments of a turbulent cloud. The eastern group is spatially and kinematically associated with the gas pillar receding away from NGC2244. This group might be formed by feedback from massive stars in NGC2244. Our results suggest that the stellar population in the Rosette Nebula may form through three different processes: the expansion of stellar clusters, hierarchical star formation in turbulent clouds, and feedback-driven star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/461/11
- Title:
- Radio observations of MYSO candidates
- Short Name:
- J/A+A/461/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey is a multi-wavelength programme of follow-up observations designed to distinguish between genuine massive young stellar objects (MYSOs) and other embedded or dusty objects, such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe). We have identified nearly 2000 MYSOs candidates by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. There are several other types of embedded or dust enshrouded objects that have similar colours as MYSOs and contaminate our sample. Two sources of contamination are from UCHII regions and PNe, both of which can be identified from the radio emission emitted by their ionised nebulae. In order to identify UCHII regions and PNe that contaminate our sample we have conducted high resolution radio continuum observations at 3.6 and 6cm of all southern MYSOs candidates (235{deg}<l<350{deg}) using the Australia Telescope Compact Array (ATCA). These observations have a spatial resolution of ~1-2" and typical image rms noise values of ~0.3mJy, sensitive enough to detect a HII region powered by a B0.5 star at the far side of the Galaxy. Of the 826 RMS sources observed we found 199 to be associated with radio emission, ~25% of the sample. The Galactic distribution, morphologies and spectral indices of the radio sources associated with the RMS sources are consistent with these sources being UCHII regions. Importantly, the 627 RMS sources for which no radio emission was detected are still potential MYSOs. In addition to the 802 RMS fields observed we present observations of a further 190 fields. These observations were made towards MSX sources that passed cuts in earlier versions of the survey, but were later excluded.
- ID:
- ivo://CDS.VizieR/J/A+A/525/A149
- Title:
- Red MSX Survey (RMS): bolometric fluxes of YSOs
- Short Name:
- J/A+A/525/A149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey is returning a large sample of massive young stellar objects (MYSOs) and ultra-compact (UC) HII regions using follow-up observations of colour-selected candidates from the MSX point source catalogue. To obtain the bolometric fluxes and, using kinematic distance information, the luminosities for young RMS sources with far-infrared fluxes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/410/1237
- Title:
- Red MSX survey (RMS) massive young stars
- Short Name:
- J/MNRAS/410/1237
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey has identified a large sample of massive young stellar objects and ultra compact HII regions from a sample of ~2000 MSX and Two Micron All Sky Survey (2MASS) colour selected sources. Using a recent catalogue of molecular clouds derived from the Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS), and by applying a Galactic scaleheight cut-off of 120pc, we solve the distance ambiguity for RMS sources located within 18{deg}<|l|>54{deg}. These two steps yield kinematic distances to 291 sources out of a possible 326, located within the GRS longitude range. Combining distances and integrated fluxes derived from spectral energy distributions, we estimate luminosities to these sources and find that >90 per cent are indicative of the presence of a massive star. We find the completeness limit of our sample is ~10^4^L_{sun}_, which corresponds to a zero-age main-sequence star with a mass of ~12M_{sun}_. Selecting only these sources, we construct a complete sample of 196 sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/1689
- Title:
- Red MSX water maser and ammonia emissions
- Short Name:
- J/MNRAS/418/1689
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Red MSX Source (RMS) survey has identified a sample of ~1200 massive young stellar objects (MYSOs), compact and ultra-compact HII regions from a sample of ~2000 MSX and Two Micron All Sky Survey (2MASS) colour-selected sources. We have used the 100-m Green Bank Telescope to search for 22-24GHz water maser and ammonia (1,1), (2,2) and (3,3) emission towards ~600 RMS sources located within the northern Galactic plane. We have identified 308 H_2_O masers which corresponds to an overall detection rate of ~50 per cent. We find no significant difference in the detection rate for HII regions and MYSOs which would suggest that the conditions required to produce maser emission are equally likely in both phases. Comparing the detection rates as a function of luminosity, we find the H_2_O detection rate has a positive dependence on the source luminosity, with the detection rate increasing with increasing luminosity.
- ID:
- ivo://CDS.VizieR/J/ApJ/825/91
- Title:
- Refined classification for Orion A protostars
- Short Name:
- J/ApJ/825/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the list of young stellar objects (YSOs) compiled by Megeath et al. (2012, J/AJ/144/192) for the Orion A molecular cloud, only 44 out of 1208 sources found projected onto low extinction (A_K_<0.8mag) gas are identified as protostars. These objects are puzzling because protostars are not typically expected to be associated with extended low extinction material. Here, we use high resolution extinction maps generated from Herschel data, optical/infrared and Spitzer Space Telescope photometry and spectroscopy of the low extinction protostellar candidate sources to determine if they are likely true protostellar sources or contaminants. Out of 44 candidate objects, we determine that 10 sources are likely protostars, with the rest being more evolved YSOs (18), galaxies (4), false detections of nebulosity and cloud edges (9), or real sources for which more data are required to ascertain their nature (3). We find none of the confirmed protostars to be associated with recognizable dense cores and we briefly discuss possible origins for these orphaned objects.
