First Observed Interaction of the Circumstellar Envelope of an S-star with the Environment of Sgr A*

Peißker, F.; Ali, B.; Eckart, A.; Hosseini, S. Elaheh; Karas, V.; Clénet, Y.; Sabha, Nesrin; Labadie, Lucas; Subroweit, M.

doi:10.3847/1538-4357/abd9c6

Cited by 14 publications

(41 citation statements)

References 77 publications

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“…30 (10 exposures, 28.0 s total integration time). We want to highlight that these data were also analyzed in Parsa et al (2017), Peißker et al (2019b, 2020a, 2020b, 2020c, 2020d, Ali et al (2020), Peißker et al (2021a, 2021b), and Peißker et al (2021c.…”

Section: Discussionmentioning

confidence: 99%

Observation of S4716—a Star with a 4 yr Orbit around Sgr A*

Peißker

Eckart

Britzen

2022

ApJ

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The ongoing monitoring of the Galactic center and Sgr A*, the central supermassive black hole, produces surprising and unexpected findings. This goes hand in hand with the technical evolution of ground- and space-based telescopes and instruments, but also with the progression of image filter techniques such as the Lucy–Richardson algorithm. As we continue to trace the members of the S cluster close to Sgr A* on their expected trajectory around the supermassive black hole, we present the finding of a new stellar source, which we call S4716. The newly found star orbits Sgr A* in about 4.0 yr and can be detected with NIRC2 (Keck), OSIRIS (Keck), SINFONI (VLT), NACO (VLT), and GRAVITY (VLTI). With a periapse distance of about 100 au, S4716 shows an equivalent distance toward Sgr A* as S4711. These fast-moving stars undergo a similar dynamical evolution, since S4711–S4716 share comparable orbital properties. We will furthermore draw a connection between the recent finding of a new faint star called S300 and the data presented here. Additionally, we observed a blend-star event with S4716 and another newly identified S star S148 in 2017.

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Section: Discussionmentioning

confidence: 99%

Observation of S4716—a Star with a 4 yr Orbit around Sgr A*

Peißker

Eckart

Britzen

2022

ApJ

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“…A number of bow shock sources were detected in the innermost parsec of the Galactic centre (Mužić et al, 2010;Peißker et al, 2021). They exhibit distinct characteristics, including an excess towards mid-infrared wavelengths and a significant linear polarization.…”

Section: Strong-gravity Effects On the Appearance Of Stars And Hot Sp...mentioning

confidence: 99%

Electromagnetic signatures of strong-field gravity from accreting black holes

Karas,

Zajacek,

Kunneriath

et al. 2021

Preprint

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Observations of galactic nuclei help us to test General Relativity. Whereas the No-hair Theorem states that classical, isolated black holes eventually settle to a stationary state that can be characterized by a small number of parameters, cosmic black holes are neither isolated nor steady. Instead, they interact with the environment and evolve on vastly different time-scales. Therefore, the astrophysically realistic models require more parameters, and their values likely change in time. New techniques are needed in order to allow us to obtain independent constraints on these additional parameters. In this context, non-electromagnetic messengers have emerged and a variety of novel electromagnetic observations is going to supplement traditional techniques in the near future. In this outline, we summarize several fruitful aspects of electromagnetic signatures from accretion disks in strong-gravity regime in the outlook of upcoming satellite missions and ground-based telescopes. As an interesting example, we mention a purely geometrical effect of polarization angle changes upon light propagation, which occurs near the black hole event horizon. Despite that only numerical simulations can capture the accretion process in a realistic manner, simplified toy-models and semi-analytical estimates are useful to understand complicated effects of strong gravity near the event horizon of a rotating black hole, and especially within the plunging region below the innermost stable circular orbit.

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“…The extended region of low excitation centered on Sgr A * (Schödel et al 2007) and the mass-losing envelope, along with the extended tail of IRS 7 (Yusef-Zadeh & Melia 1992), could also be influenced by a strong central wind coming from the central few arcseconds. Closer to Sgr A * , the orientation of infrared-excess, comet-shaped sources X7, X3, and X8 suggests the presence of a fast, collimated outflow that originates in the Sgr A * accretion flow or in the collective wind of OB/WR stars (Mužić et al 2010;Peißker et al 2019;Yusef-Zadeh et al 2020;Peißker et al 2021). The nuclear outflow that nearly balances the inflow is also consistent with the flat number density profile of hot plasma, n e ∝ r −0.5 , inside the Bondi radius, as inferred from the analysis of the X-ray bremsstrahlung surfacedensity profile (Wang et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Mid-infrared Studies of Dusty Sources in the Galactic Center

Bhat

Sabha

Eckart

et al. 2022

ApJ

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Mid-infrared (MIR) images of the Galactic center show extended gas and dust features along with bright infrared sources (IRS). Some of these dust features are a part of ionized clumpy streamers orbiting Sgr A*, known as the mini-spiral. We present their proper motions over a 12 yr time period and report their flux densities in N-band filters and derive their spectral indices. The observations were carried out by VISIR at the ESO’s Very Large Telescope. High-pass filtering led to the detection of several resolved filaments and clumps along the mini-spiral. Each source was fit by a 2D Gaussian profile to determine the offsets and aperture sizes. We perform aperture photometry to extract fluxes in two different bands. We present the proper motions of the largest consistent set of resolved and reliably determined sources. In addition to stellar orbital motions, we identify a stream-like motion of extended clumps along the mini-spiral. We also detect MIR counterparts of the radio tail components of the IRS 7 source. They show a clear kinematical deviation with respect to the star. They likely represent Kelvin–Helmholtz instabilities formed downstream in the shocked stellar wind. We also analyze the shape and orientation of the extended late-type IRS 3 star that is consistent with the Atacama Large Millimeter/submillimeter Array submillimeter detection of the source. Its puffed-up envelope with a radius of ∼2 × 106 R ⊙ could be the result of the red-giant collision with a nuclear jet, which was followed by tidal prolongation along the orbit.

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First Observed Interaction of the Circumstellar Envelope of an S-star with the Environment of Sgr A*

Cited by 14 publications

References 77 publications

Observation of S4716—a Star with a 4 yr Orbit around Sgr A*

Observation of S4716—a Star with a 4 yr Orbit around Sgr A*

Electromagnetic signatures of strong-field gravity from accreting black holes

Mid-infrared Studies of Dusty Sources in the Galactic Center

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