Excitation Mechanism of O i Lines in Herbig Ae/Be Stars

Mathew, Blesson; Manoj, P.; Narang, Mayank; Banerjee, D. P. K.; Nayak, Pratheeksha; Muneer, S.; Vig, S.; Kumar, Sahana; Paul, K. T.; Maheswar, G.

doi:10.3847/1538-4357/aab3d8

Cited by 20 publications

(16 citation statements)

References 49 publications

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“…-GU CMA -Herbig Ae/Be -It is generally considered as a Herbig Ae/Be star (e.g. Ababakr et al 2017;Fairlamb et al 2015;Reiter et al 2018;Mathew et al 2018). -HBC 7 -Herbig Ae/Be -It is a bit doubtful but Hernández et al (2004) argue that it shows charecteristics of PMS objects.…”

Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

“…Cauley & Johns-Krull (2014) -HD 37490 -Classical Be - Cauley & Johns-Krull (2014) and Wheelwright et al (2010) -V1493 Cyg -Herbig Ae/Be -It has been little studied in the recent years but appears as a Herbig Ae/Be star in The et al (1994) and in a few papers since then (e.g. Mathew et al 2018) although Hernández et al (2004) was unable to classify it. Regarding the unclassified B[e] or FS CMa stars, almost all the confirmed FS CMa objects are listed in Lamers et al (1998), Miroshnichenko (2007), Miroshnichenko et al (2007Miroshnichenko et al ( , 2017, and Khokhlov et al (2018) (Frasca et al 2016), MWC 930 looks like a luminous blue variable (Martayan et al 2016;Jiang et al 2018) and MWC 623 seems clear to be a FS CMa star (Miroshnichenko 2007;Polster et al 2018).…”

Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

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Catalogue of new Herbig Ae/Be and classical Be stars

Vioque

Oudmaijer

Schreiner³

et al. 2020

A&A

115

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Context. The intermediate-mass pre-main sequence Herbig Ae/Be stars are key to understanding the differences in formation mechanisms between low- and high-mass stars. The study of the general properties of these objects is hampered by the lack of a well-defined, homogeneous sample, and because few and mostly serendipitously discovered sources are known. Aims. Our goal is to identify new Herbig Ae/Be candidates to create a homogeneous and well defined catalogue of these objects. Methods. We have applied machine learning techniques to 4 150 983 sources with data from Gaia DR2, 2MASS, WISE, and IPHAS or VPHAS+. Several observables were chosen to identify new Herbig Ae/Be candidates based on our current knowledge of this class, which is characterised by infrared excesses, photometric variabilities, and Hα emission lines. Classical techniques are not efficient for identifying new Herbig Ae/Be stars mainly because of their similarity with classical Be stars, with which they share many characteristics. By focusing on disentangling these two types of objects, our algorithm has also identified new classical Be stars. Results. We have obtained a large catalogue of 8470 new pre-main sequence candidates and another catalogue of 693 new classical Be candidates with a completeness of 78.8 ± 1.4% and 85.5 ± 1.2%, respectively. Of the catalogue of pre-main sequence candidates, at least 1361 sources are potentially new Herbig Ae/Be candidates according to their position in the Hertzsprung-Russell diagram. In this study we present the methodology used, evaluate the quality of the catalogues, and perform an analysis of their flaws and biases. For this assessment, we make use of observables that have not been accounted for by the algorithm and hence are selection-independent, such as coordinates and parallax based distances. The catalogue of new Herbig Ae/Be stars that we present here increases the number of known objects of the class by an order of magnitude.

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Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

Section: Appendix A: Disentangling Herbig Ae/be Cbe Stars and B[e] mentioning

confidence: 99%

Catalogue of new Herbig Ae/Be and classical Be stars

Vioque

Oudmaijer

Schreiner³

et al. 2020

A&A

115

View full text Add to dashboard Cite

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“…3; however the 1.3168 µm line ( 3 S1− 3 P2) is not detected. In most stellar environments this would suggest that continuum fluorescence is unlikely to play a significant role in the excitation of the first two of the above O i lines (e.g., Mathew et al 2018). The 7002 Å and 7254 Å O i lines, which would also be expected if continuum fluorescence were important (Rodríguez-Ardila et al 2002), were not present in an optical spectrum of SO obtained in 2013 (van Hoof et al 2015a).…”

Section: The O I Linesmentioning

confidence: 98%

V4334 Sgr (Sakurai’s Object): still churning out the dust

Evans

Banerjee

Geballe

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a 0.8–2.5 μm spectrum of the Very Late Thermal Pulse object V4334 Sgr (Sakurai’s Object), obtained in 2020 September. The spectrum displays a continuum that rises strongly to longer wavelengths, and is considerably brighter than the most recent published spectrum obtained seven years earlier. At the longer wavelengths the continuum is well fitted by a blackbody with a temperature of 624 ± 8 K. However, there is excess continuum at the shortest wavelengths that we interpret as being due to hot dust that has very recently formed in an environment with C/O ≃ 2.5. Other possible sources for this excess continuum are discussed – such as the stellar photosphere dimly seen through the dust shell, and light scattered off the inner wall of the dust torus – but these interpretations seem unlikely. Numerous emission lines are present, including those of He i, C i, [C i], and O i. Our observations confirm that emission in the He i 1.083 μm and [C i] 0.9827/0.9852 μm lines is spatially extended. The [C i] line fluxes suggest that the electron density increased by an order of magnitude between 2013 and 2020, and that these two lines may soon disappear from the spectrum. The flux ratio of the 1.083 μm and 2.058 μm He i lines is consistent with the previously-assumed interstellar extinction. The stellar photosphere remains elusive, and the central star may not be as hot as suggested by current evolutionary models.

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“…We observed the optical spectra of IL Cep using the Himalayan Faint Object Spectrograph Camera (HFOSC) mounted on the 2m Himalayan Chandra Telescope (HCT). The spectrum of IL Cep is reported in the study of Mathew et al (2018), which discusses primarily about the O lines in HAeBe stars rather than elaborating the spectral details of IL Cep. Further, we observed the spectrum of IL Cep B during our recent observation run using the OMR spectrograph (details are given in Sect.…”

Section: Il Cep Multiple Systemmentioning

confidence: 99%

Clustering of low mass stars around Herbig Be star IL Cep -- Evidence of "Rocket Effect" using Gaia EDR3 ?

Arun,

Mathew,

Maheswar

et al. 2021

Preprint

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We study the formation and the kinematic evolution of the early type Herbig Be star IL Cep and its environment. The young star is a member of the Cep OB3 association, at a distance of 798±9 pc, and has a "cavity" associated with it. We found that the B0V star HD 216658, which is astrometrically associated with IL Cep, is at the center of the cavity. From the evaluation of various pressure components created by HD 216658, it is established that the star is capable of creating the cavity. We identified 79 co-moving stars of IL Cep at 2 pc radius from the analysis of Gaia EDR3 astrometry. The transverse velocity analysis of the co-moving stars shows that they belong to two different populations associated with IL Cep and HD 216658, respectively. Further analysis confirms that all the stars in the IL Cep population are mostly coeval (∼ 0.1 Myr). Infrared photometry revealed that there are 26 Class II objects among the co-moving stars. The stars without circumstellar disk (Class III) are 65% of all the co-moving stars. There are 9 intense H𝛼 emission candidates identified among the co-moving stars using IPHAS H𝛼 narrow-band photometry. The dendrogram analysis on the Hydrogen column density map identified 11 molecular clump structures on the expanding cavity around IL Cep, making it an active star-forming region. The formation of the IL Cep stellar group due to the "rocket effect" by HD 216658 is discussed.

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Excitation Mechanism of O i Lines in Herbig Ae/Be Stars

Cited by 20 publications

References 49 publications

Catalogue of new Herbig Ae/Be and classical Be stars

Catalogue of new Herbig Ae/Be and classical Be stars

V4334 Sgr (Sakurai’s Object): still churning out the dust

Clustering of low mass stars around Herbig Be star IL Cep -- Evidence of "Rocket Effect" using Gaia EDR3 ?

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