Upsilon Serpentis
A-type main-sequence star in Serpens, suspected astrometric binary.
Upsilon Serpentis, also designated υ Serpentis, lies in the Serpens Caput portion of the Serpens constellation. Faintly visible without a telescope at an apparent visual magnitude of +5.70, it is roughly 250 light-years away based on a measured annual parallax of 13.04 milliarcseconds. This star belongs to the Hyades group, a moving stream of stars that travel along a path similar to the Hyades star cluster.
Classified as an A3 V main-sequence star, Upsilon Serpentis has about 2.9 times the Sun’s mass and roughly 2.2 times its radius. At an estimated 403 million years old, it spins rapidly, with a projected rotational velocity of 133 km/s. Its photosphere radiates about 23 times the Sun’s luminosity at an effective temperature of 8,917 K.
The system is a suspected astrometric binary, meaning an unseen companion may be tugging on the visible star’s motion. X-ray emission has been detected from the system, with a certain luminosity, which could originate from that companion—since A-type stars are not typically expected to produce X-rays.
- Apparent visual magnitude
- +5.70
- Distance
- ~250 light years
- Spectral type
- A3 V
- Mass
- 2.9 M☉
- Radius
- 2.2 R☉
- Luminosity
- 23 L☉
- Effective temperature
- 8,917 K
- Projected rotational velocity
- 133 km/s
- Age
- 403 million years
Lore & Background
Upsilon Serpentis is an A-type main-sequence star with a stellar classification of A3 V. It has an estimated 2.9 times the mass of the Sun and about 2.2 times the Sun's radius. At an age of 403 million years, it rotates rapidly with a projected rotational velocity of 133 km/s. The star radiates 23 times the solar luminosity from its photosphere at an effective temperature of 8,917 K. It is a suspected astrometric binary, meaning an undetected companion perturbs the motion of the visible star. An X-ray emission has been detected from this system, possibly originating from the companion, as A-type stars are not expected to emit X-rays.
Reader's Guide
Upsilon Serpentis is notable as a suspected astrometric binary, where the presence of an unseen companion is inferred from perturbations in the visible star's motion. The detection of X-ray emission from the system adds to this interest, because A-type stars like Upsilon Serpentis are not expected to produce X-rays on their own, suggesting the emission may come from the companion. Its membership in the Hyades group links it to a well-known stellar stream, providing context for studies of stellar kinematics and evolution. The star's rapid rotation and relatively young age of 403 million years make it a useful object for investigating the behavior of intermediate-mass stars. While the companion remains undetected directly, the astrometric and X-ray evidence keeps Upsilon Serpentis a target for further observation in binary star research.
Did You Know?
- Upsilon Serpentis is a suspected astrometric binary, with an undetected companion perturbing its motion.
- It is a member of the Hyades group, a stream of stars with a trajectory similar to the Hyades cluster.
- The star has a high rotational velocity of 133 km/s.
Frequently Asked Questions
What is Upsilon Serpentis?
Upsilon Serpentis (υ Serpentis) is a faint A-type main-sequence star located in the Serpens Caput section of the Serpens constellation. It is just barely visible to the unaided eye, sitting at an apparent visual magnitude of +5.70.
How far away is Upsilon Serpentis?
Its measured annual parallax of 13.04 milliarcseconds places it at roughly 250 light-years from Earth, making it a moderately nearby stellar neighbor.
What are the key physical properties of Upsilon Serpentis?
Classified as an A3 V star, it carries about 2.9 solar masses, a radius of roughly 2.2 solar radii, and a luminosity near 23 times that of the Sun. At an estimated 403 million years of age, it also rotates rapidly on its axis.
Is Upsilon Serpentis a confirmed binary or multiple star system?
It is currently flagged as a suspected astrometric binary, meaning a companion is inferred from subtle positional wobbles rather than directly imaged. As of the latest catalog entries, no visual or spectroscopic companion has been firmly confirmed.
What stellar group does Upsilon Serpentis belong to?
It is a member of the Hyades moving group, a stream of stars that share a common spatial trajectory similar to the well-known Hyades cluster. This membership implies it likely formed in the same broad region as those cluster stars before drifting apart.
More in Binary and Multiple Stars, Part 5 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced