VLA Observations of Sgr A

1983 ◽  
pp. 65-69 ◽  
Author(s):  
W. M. Goss ◽  
U. J. Schwarz ◽  
R. D. Ekers ◽  
J. H. van Gorkom
Keyword(s):  
Sgr A

scholarly journals Metrics and Motivations for Earth–Space VLBI: Time-resolving Sgr A* with the Event Horizon Telescope

2019 ◽  
Vol 881 (1) ◽  
pp. 62 ◽  
Author(s):  
Daniel C. M. Palumbo ◽  
Sheperd S. Doeleman ◽  
Michael D. Johnson ◽  
Katherine L. Bouman ◽  
Andrew A. Chael
Keyword(s):  
Event Horizon ◽  
Earth Space ◽  
Sgr A

scholarly journals Using infrared/X-ray flare statistics to probe the emission regions near the event horizon of Sgr A*

2016 ◽  
Vol 461 (1) ◽  
pp. 552-559 ◽  
Author(s):  
S. Dibi ◽  
S. Markoff ◽  
R. Belmont ◽  
J. Malzac ◽  
J. Neilsen ◽  
...  
Keyword(s):  
Event Horizon ◽  
X Ray ◽  
Sgr A

scholarly journals NEAR-INFRARED AND X-RAY QUASI-PERIODIC OSCILLATIONS IN NUMERICAL MODELS OF Sgr A*

2012 ◽  
Vol 746 (1) ◽  
pp. L10 ◽  
Author(s):  
Joshua C. Dolence ◽  
Charles F. Gammie ◽  
Hotaka Shiokawa ◽  
Scott C. Noble
Keyword(s):  
Near Infrared ◽  
Numerical Models ◽  
Periodic Oscillations ◽  
X Ray ◽  
Sgr A

scholarly journals 2D kinematics of massive stars near the Galactic Centre

2020 ◽  
Vol 500 (3) ◽  
pp. 3213-3239
Author(s):  
Mattia Libralato ◽  
Daniel J Lennon ◽  
Andrea Bellini ◽  
Roeland van der Marel ◽  
Simon J Clark ◽  
...  
Keyword(s):  
Moving Objects ◽  
Hubble Space Telescope ◽  
Massive Stars ◽  
Line Of Sight ◽  
Galactic Centre ◽  
Harsh Environment ◽  
Proper Motions ◽  
Sgr A ◽  
Better Than ◽  
Rule Out

ABSTRACT The presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A* based on high-precision proper motions obtained with the Hubble Space Telescope. Thanks to a careful data reduction, well-measured bright stars in our proper-motion catalogues have errors better than 0.5 mas yr−1. We discuss the absolute motion of the MSs in the field and their motion relative to Sgr A*, the Arches, and the Quintuplet. For the majority of the MSs, we rule out any distance further than 3–4 kpc from Sgr A* using only kinematic arguments. If their membership to the GC is confirmed, most of the isolated MSs are likely not associated with either the Arches or Quintuplet clusters or Sgr A*. Only a few MSs have proper motions, suggesting that they are likely members of the Arches cluster, in agreement with previous spectroscopic results. Line-of-sight radial velocities and distances are required to shed further light on the origin of most of these massive objects. We also present an analysis of other fast-moving objects in the GC region, finding no clear excess of high-velocity escaping stars. We make our astro-photometric catalogues publicly available.

scholarly journals On the 2PN Pericentre Precession in the General Theory of Relativity and the Recently Discovered Fast-Orbiting S-Stars in Sgr A*

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 37
Author(s):  
Lorenzo Iorio
Keyword(s):  
General Theory ◽  
Present Author ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Orbital Elements ◽  
Analytical Expression ◽  
Potential Interest ◽  
Short Period ◽  
The Future ◽  
Sgr A

Recently, the secular pericentre precession was analytically computed to the second post-Newtonian (2PN) order by the present author with the Gauss equations in terms of the osculating Keplerian orbital elements in order to obtain closer contact with the observations in astronomical and astrophysical scenarios of potential interest. A discrepancy in previous results from other authors was found. Moreover, some of such findings by the same authors were deemed as mutually inconsistent. In this paper, it is demonstrated that, in fact, some calculation errors plagued the most recent calculations by the present author. They are explicitly disclosed and corrected. As a result, all of the examined approaches mutually agree, yielding the same analytical expression for the total 2PN pericentre precession once the appropriate conversions from the adopted parameterisations are made. It is also shown that, in the future, it may become measurable, at least in principle, for some of the recently discovered short-period S-stars in Sgr A*, such as S62 and S4714.

scholarly journals A Nonthermal Bomb Explains the Near-infrared Superflare of Sgr A*

2020 ◽  
Vol 891 (2) ◽  
pp. L36 ◽  
Author(s):  
Eduardo M. Gutiérrez ◽  
Rodrigo Nemmen ◽  
Fabio Cafardo
Keyword(s):  
Near Infrared ◽  
Sgr A

scholarly journals Class I methanol masers in the Galactic center

2013 ◽  
Vol 9 (S303) ◽  
pp. 147-149
Author(s):  
L. O. Sjouwerman ◽  
Y. M. Pihlström
Keyword(s):  
Galactic Center ◽  
Class I ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Sagittarius A ◽  
Current Location ◽  
Theoretical Predictions ◽  
Methanol Masers ◽  
Sgr A

AbstractWe report on the detection of 36 and 44 GHz Class I methanol (CH3OH) maser emission in the Sagittarius A (Sgr A) complex with the Karl G. Jansky Very Large Array (VLA). These VLA observations show that the Sgr A complex harbors at least three different maser tracers of shocked regions in the radio regime. The 44 GHz masers correlate with the positions and velocities of previously detected 36 GHz CH3OH masers, but less with 1720 MHz OH masers. Our detections agree with theoretical predictions that the densities and temperatures conducive for 1720 MHz OH masers may also produce 36 and 44 GHz CH3OH maser emission. However, many 44 GHz masers do not overlap with 36 GHz methanol masers, suggesting that 44 GHz masers also arise in regions too hot and too dense for 36 GHz masers to form. This agrees with the non-detection of 1720 MHz OH masers in the same area, which are thought to be excited under even cooler and less dense conditions. We speculate that the geometry of the 36 GHz masers outlines the current location of a shock front.

scholarly journals V5116 Sgr: A disc-ecipsed SSS post-outburst nova?

2010 ◽  
Vol 331 (2) ◽  
pp. 201-204 ◽  
Author(s):  
G. Sala ◽  
M. Hernanz ◽  
C. Ferri ◽  
J. Greiner
Keyword(s):  
Sgr A

VLBA observation of a radio intraday flare of Sgr A*

2003 ◽  
Vol 324 (S1) ◽  
pp. 403-406
Author(s):  
Makoto Miyoshi ◽  
Hiroshi Imai ◽  
Junichi Nakashima ◽  
Shuji Deguchi ◽  
Zhi-Qiang Shen
Keyword(s):  
Sgr A

scholarly journals HerschelHIFI observations of the Sgr A +50 km s-1Cloud

2015 ◽  
Vol 584 ◽  
pp. A118 ◽  
Author(s):  
Aa. Sandqvist ◽  
B. Larsson ◽  
Å. Hjalmarson ◽  
P. Encrenaz ◽  
M. Gerin ◽  
...  
Keyword(s):  
Sgr A
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